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What's new in GRIP

Note that the version number of GRIP is the date on which it was released on this site. Eg, 8.1.13 is 2008 January 13th.

• OOPS! The current zip file for download has an incorrect version of the file run.bat containing the (Windows) commands for launching GRIP. This will be corrected as soon as possible. Meanwhile the correction is described here. With apologies and many thanks to Rob Wilkinson in New Zealand for pointing this out.
• Version 10.5.7
  • The star chart dialogue (New star chart on the file menu of GRIP) now gets the coordinates of an object and the data for the star chart directly from the public Simbad database (at the Centre de Données Stellaires in Strasbourg) without requiring AstroGrid to be installed or running. A live internet connection is needed of course.
    NB: During testing I have found (and reported to CDS) that the positions of stars with identifiers containing the word "Melotte" are not very accurate and sometimes result in stars being duplicated in the chart.
  • For programmers: some refactoring has been done to move several general-purpose classes to the higher level package net.grelf. This enables them to be reused more easily without being dependent on any classes in net.grelf.astro or net.grelf.grip. Only one method signature has had to be changed: Util.saveJTableAsCSV ().
• Version 10.4.5
  • The speed of combining a large sets of images has been improved significantly. I was finding with my 23 Mpixel images that the warping step slowed by a factor of 3 after the 9th image. There is now no slow-down.
  • For programmers: the access to logging has changed so that classes that log anything no longer necessarily require the GRIP class for compiling or running.
• NB AstroGrid has recently been updated. The JAR file is now called acr-interface-1.3.2.jar (previously acr-interface-1.2.2.jar). The good news is that GRIP does not need recompiling to work with the new version. So if you are using AstroGrid services from GRIP simply replace that JAR file and edit GRIP's run.bat file for the one-character change.
• Version 10.2.12
  • On the main GRIP file menu, saved HTML pages of reference stars from AAVSO can now be loaded as star charts and then saved as .chart files in GRIP's (XML) format.
  • On the batch menu a new option enables .chart files to be merged. So by using this and the previous item, AAVSO reference stars can be incorporated very easily into charts drawn from Hipparcos and Tycho data (either from local files or via AstroGrid). Note that if a magnitude for a given band has already been found when another chart refers to the same star, the magnitude is not changed by the second occurence. Therefore the reference chart must come first in the list to be merged.
  • Unfortunately the improvements to the handling of Dec values in 10.2.7 caused problems in reloading saved .chart and .blobs files. That has been corrected. Any files saved with previous versions will now load.
  • Programmers should note the new class net.grelf.grip.Maths which correctly calculates statistics of a list of angles even when they spread across the jump between 360 and 0 degrees. If you search on the internet for averaging angles you will find methods that are definitely wrong (they may work for special sets of values but not generally). I needed these statistics for calculating the centre and size of any merged star charts.

  The reason I am doing so much with charts is that I plan to be able to map photos onto charts automatically. Then measuring positions and magnitudes will be really easy.

• Version 10.2.7

  Numerous small improvements arising from testing, of which the following are the most significant.

  • Measuring small angular separations on photos is now more accurate.
  • Display of position values (RA and Dec) no longer repeats the whole number part of the seconds as the fractional part (internally the values were correct)!
  • On the star chart dialogue the fields for entering declination values had a possibility of ambiguity when the degree value was zero. This is now correctly handled: if you put -0 as the degree field it will be realised that the minute and seconds fields should be interpreted as negative, regardless of whether you also put minus signs in those fields. Declination values returned from the Sesame service are displayed such that any minus sign goes in the degrees field, even if that is zero, and it will be interpreted correctly when going on to create a chart. Programmers will find that the documentation of class net.grelf.astro.Dec has changed in the light of this.
  • I think the problem is finally solved in which star charts could not be created if the AstroGrid JAR files were not present.
• Version 10.1.20
  • Metadata written into the image resulting from combining a sequence of images now has the correct month!
  • The XML saved from the magnitude graph is now well-formed (one element was not paired correctly).
  • Star charts saved as XML now include the chart caption as a <Chart> element and the caption is editable from the image menu. Also reloading star charts is more tolerant of different formats for RA and Dec values.
• Version 10.1.16
  • The magnitude graph has a new button, to save the results as XML. The XML is designed to be easy to incorporate into a larger XML file covering a large number of such observations, perhaps of several different stars and using different charts and equipment (all identifiable in the XML).
  • The batch menu has been rearranged, putting the astro-process near the top. At the same time that option has been renamed more explicitly as "Astro combine into 1 image". Also there is no longer a choice between camera or telescope versions of the option (which were only to help the user to decide which options to tick in the dialogue that appears before processing). It will be a while before these pages are all revised, so wherever we refer to the "batch astro-process" it means this option, for combining a set of images into 1. Some tool-tip text has been added to the menu to explain.
  • A new option on the batch menu is "Astro warp onto common basis". This is quite similar to the old astro-process except that the images are not combined. Instead each is separately distorted and re-saved with _warp in the file name. The distortion (done in the same way as in the older process) ensures that the centre of each blob (star) is at the same (x, y) position in every image. This prepares for analysing star variability in a sequence of images over potentially long time spans.
  • Another new option on the batch menu is "Accumulate images into 1". This does the same processing as the old "Average images", using the 32-bits-per-channel accumulator. The difference comes at the end. Averaging simply divides all levels by the number of images and writes back into a normal (8- or 16-bit) image. The new option instead presents a curves dialogue and histogram of the accumulator so that maximum contrast can be obtained in the result when it is written back into a normal image.
  • The dialogue displayed at the start of the batch astro processing has been considerably improved, with some new adjustable parameters.
  • It has been made harder to accidentally close an image window while processing is continuing, which could cause worrying error messages.
• Version 10.1.13
  • Magnitude estimation does now use multiple wavebands (eg, Johnson U, B, V, R, I) if they are available in the reference star data. A new dialogue makes it possible to say which waveband should be used for each channel of an image (either monochrome or RGB). The default assignment for monochrome images is to use V band and for RGB to use RVB respectively (and V for the overall brightness measurement). The resulting graph indicates in a key which bands were in fact used for each of the reference stars. All reference stars should of course use the same bands - there is no reason why they should not but the graph legend confirms it.
  • Confidence intervals are now shown in the magnitude estimation graph, using the calculation scheme decribed here. Experiments on my own images show that the errors in the brightness measurements are smaller than in the supposedly known magnitudes of the reference stars. Hipparcos and Tycho data do include standard error estimates which reinforce this conclusion. So perhaps the graph was the right way round earlier - magnitude as the y-axis and log brightness as x. I am not proposing to change it again for my own purposes.
  • A smaller font is used for the reference stars on the magnitude estimation graph and the annotated star chart, to reduce confusion where text overlaps. The graph now uses a key listing reference stars to further reduce the clutter.
  • The magnitude estimation graph now also shows the name of the image that was measured and the start and end of the total exposure sequence used to create the image (both as date/time strings and as Julian dates).
  • The combined image created by the batch astro-process now contains metadata including camera settings and the overall start and end times of the exposure sequence. This is all stored as a semicolon-separated sequence in the ImageDescription tag of a TIFF structure. It is therefore visible in other applications such as PhotoShop. GRIP can decode the sequence again to make use of each item, eg to show times as Julian dates in the magnitude estimation graph.
  • If a star chart is opened from a disc file and it contains stars having user-entered ids (<OtherId> elements) those stars are assumed to be in use as reference stars for magnitude estimation and are highlighted in small red squares on the display. This is to make it much easier to go through a reference sequence and identify the same stars on images being measured. It is possible to edit <OtherId> elements into the XML .chart file with a text editor and this may be the quickest way to set known stars as references, from their other (eg, Tycho) ids.
  • The chart annotation done when estimating magnitudes is now more flexible: the list of open images is searched for any chart that contains the reference stars and that chart is copied and annotated.
  • Magnitudes in band I are loaded from the Hipparcos data file, hip_main.dat. I is not available in the corresponding Tycho file, tyc-main.dat. Magnitudes in bands V and B were already loaded from both files.
  • Image information (on the image menu) now also shows the time of taking the photo as a Julian date, to the nearest second. To support that a new field in the configuration menu is for setting your local time zone offset, though the system should set that automatically when the configuration file (grip.properties) is first created.
  • A handy new Julian date conversion dialogue is also available from the configuration menu.
  • If an image which has associated blob/star data is cropped (via the geometry menu) then the blob data are modified so they remain valid for the cropped image.
  • Fixed some small problems: Tycho ids were not appearing in star charts generated from local data files, XML .chart files were sometimes not well-formed for multi-band magnitude elements.
• Version 10.1.1
  • The blobs menu now enables each blob to measured accurately by using a disc completely surrounding the blob and subtracting the mean background level measured in a ring outside that. Full statistics of the background measurement are saved in the XML .blobs file to enable further analysis to be done if required. Magnitude estimation uses the more accurate brightness measurements and, as expected, straight line fits of log (brightness) against magnitude are much better. The estimation has been done for a photo I took of Nova Aquilae 2009 and full details of the method are being added to that page.
  • If blobs were identified as stars by pasting star data from a GRIP-generated star chart then an annotated copy of the chart image is also produced when magnitudes are estimated. This shows which stars were used for making the least-squares fit graph.
  • Magnitude estimation using star charts to assign star data to detected blobs in an image now works if the image is monochrome. Previously it only worked for RGB images.
  • The axes of the magnitude estimation graph have been swapped, to make clear that magnitudes are assumed to be known accurately whereas brightnesses measured from the photo are subject to error. It is intended to add error bars to the graph soon.
  • Stars in GRIP may now have multiple magnitudes, in different wavelength bands. Multiple magnitudes are now extracted from VO tables returned by AstroGrid cone search services. Alternatively the Hipparcos and Tycho data files provide both B and V magnitudes for GRIP to load from a local disc. Magnitudes other than V are not yet used in the magnitude estimation graphs but that will come soon.
  • The star chart generation dialogue now allows two possible cone search services to be used through AstroGrid: Tycho-2 and USNO-B. However in my experience so far the USNO service is unreliable. That is a shame because it can return much fainter stars for plotting in the charts.
  • The interactive star charts can now be saved as XML files (extension .chart) and reopened. When reopened they still have the full interactivity.
  • The magnitude estimation graph and the drive error analysis graph can now be saved as images (I suggest .png for smallest files).
  • New option on the measurement menu: Star spectrum. This works in steps, so you can stop after any step. It assumes you can crop the image (in step 1) to include just a star trail and corresponding spectrum. It then rotates the cropped image automatically so the spectrum is horizontal, with the star trail vertically on the left. It corrects the spectrum for wobble in the star trail then averages vertically and displays a profile from the centre of the star right along the spectrum. It is intended to develop this further.
  • GRIP's command line now recognises file paths as parameters. If the file names end in .accum, .blobs or .chart (GRIP's own file formats - the latter two XML) or the usual image file extensions then the files will be opened automatically when GRIP runs.
  • For programmers: the BlobMeas class has changed considerably to allow for the more accurate brightness measurements and background ring statistics. Consequently the XML .blobs files have also changed, though it is still possible to reload earlier ones.
• Version 9.12.14
  • New option on the measurement menu: "Calibrate from known stars". Having identified some detected blobs as stars, from a GRIP-generated star chart, simply selecting this option automatically calculates the average scale and orientation of the photo.
  • There is a new option on the measurement menu: "Blobs/stars separation data". It is only enabled if blobs have been detected in the image (from the levels menu) or reloaded from a .blobs file. It enables clicking on or near 2 blobs at a time (like measuring a straight line but the points snap to the nearest blob). The distance and slope of the line in the image are then shown. If both blobs have been identified as stars, to the extent that equatorial coordinates (RA and Dec) are known, then the position angle (PA, anticlockwise from north) and the celestial angular separation of the 2 stars is also reported. This works on the interactive star charts too - you can measure the PA and angular separation of any 2 stars. When measuring two stars identified in a photo (rather than a star chart) there is an option to overlay a meridian on the image, to show its orientation.
  • The profile drawn by measuring a straight line or a curve is now in a horizontally scrollable pane.
  • Data displays from the measurement menu have a new button, "Copy data", which copies all of the data which is listed as text to the system clipboard for other applications to paste. The data are in a crude form of HTML, as recognised by Java graphical components to control layout.
  • The naming of options on the measurement menu has been revised so that it can be seen which kind of display will result from a measurement - histogram, profile or plain text data.
  • Saving an image, which may change its name, now automatically refreshes the image table.
• Version 9.12.8

  • GRIP can now obtain data for star charts through AstroGrid. So far 2 services are used, both from the Star Chart dialogue, which now looks like this:

    

    The new field and button at the top enable you to enter the name of an object and call the Sesame service to get its coordinates, which are then automatically entered into the RA and Dec fields. For this to work you must first have AstroGrid's Virtual Observatory (VO) Desktop running. You can download that and install it by following very simple instructions on the AstroGrid site.

    Also you need to copy VODesktop's 3 jar files (the RMI versions of acr-interface-1.2.2.jar, rmi-lite-1.0.jar and commons-logging-1.0.3.jar) into a /lib directory under the directory from which GRIP is running. You can check that by examining GRIP's run.bat file. GRIP will not fail if it does not find these files but you will get a message box if you try to access the AstroGrid services.

    Sesame is a very useful service and it seems very flexible in the names it can interpret. Letter case does not matter. Constellation abbreviations and the first 3 letters to spell Greek letters are fine. NGC, M, etc, and popular names of nebulae all seem to work. In the example dialogue I have used HR Del, as I have a page on this site about it.

    The second service used, if you have the VO Desktop running, is to get the star data for the chart. At the moment that uses the Tycho-2 database of 2.5 million brightest stars. GRIP can also decode the response from the US Naval Observatory B database (even more stars) but I am not yet making that available, because of some issues mentioned below.

    If VO Desktop is not running or it fails to get the data for some reason, GRIP tries to get the data from local files holding Hipparcos and Tycho data, as before.

    There are some issues with using AstroGrid which I am attempting to clarify with them before going further. The main one is that if you set a field width greater than about 1 degree there seems to be a restriction on the amount of data coming back. The data are truncated and so cannot be marshalled across the RMI interface. Worse than that, AstroGrid does not give a message that GRIP can intercept in such cases so it just seems to fail without explanation. GRIP does not crash however - just try again or do something different.

    For Java programmers trying to use AstroGrid's API: it only took me a few days to get this far. I may be able to help if you email me.

  • This version can no longer open .blobs files saved by version 9.12.2, only the XML format saved by 9.12.3 onwards.
• Version 9.12.3
  • The format of the .blobs files introduced in version 9.12.2 has been changed to XML. This has several advantages, not least that it is human-readable as text. The file size is only about 50% greater than before. This version of GRIP is able to read either the previous format or the new XML format but will only save in the new format. Later versions will probably not be able to read the previous format, so if you were quick to use yesterday's new feature, convert your .blobs files now by opening and re-saving.
• Version 9.12.2
  • A major new feature has been added to enable blobs detected in an image to be identified as stars and have all known star data attached to them. Create a star chart for approximately the same region as the photograph. Clicking on a star in the chart displays its catalogue data (from Hipparcos and Tycho) and now also makes the star object available for use elsewhere. To associate the star with a blob do the following. On the levels menu of the photograph, threshold (either automatically or manually) to get the stars in green, then detect blobs. Then hovering over the photograph you can click near any star to see it highly magnified in a new small window. That window has a blob menu from which a new option now enables you to paste the star data. From then on that blob includes the star details in its data. You can go on to identify several stars in this way and then do magnitude estimation on others. It is hoped to extend this to make useful bulk star measurements on the photographic image, eg for monitoring all variable stars in the frame at once. Having taken one photo of a region it will be possible to automatically identify the same stars in subsequent photos (that is what GRIP does now when aligning multiple images) - watch this space!
    One thing I have done so far is to repeat the estimation of HR Del's magnitude (discussed here) by associating my photographed stars with Hipparcos and Tycho stars from a GRIP star chart:
    
    
    I hope you can see the potential of that!
  • Having spent time identifying blobs as stars in an image you would not want to lose the results. So another major new facility, accessible from both the levels menu and the blob menu, is for saving all blob data and any associated star data, in a file with extension .blobs. The saved data include the path to the image file. So for reopening the blob data and the associated image there is a new option on the main file menu of GRIP: "Open blob data & image". NB: If you subsequently want to move the image to a different directory or disc you would need to reopen the blob data and image and then resave them in the new location.
  • If you attempt to crop an image for which there are data for detected blobs, a confirmation dialogue appears to warn you before proceeding.
  • For programmers: the above has involved making several classes serialisable, particularly in the package net.grelf.astro. A .blobs file simply contains a serialisation of class BlobMeasList.
  • The option to average vertically has been removed from the levels menu.
• Version 9.11.25
  • New option on the astro-process dialogue: neutralise background.
  • The option "Auto-balance (equate modes)" on the levels menu has been renamed "Neutralise background". It still does equalise modes (assumed to relate to the sky background) but it now does it by scaling channels to match the minimum modal value rather shifting up to match the maximum. This new method ensures that bright objects do not change colour while the background becomes on average a neutral grey.
  • The histogram window displayed to assist converting the accumulator to a 16-bit image is now automatically closed when the curves dialogue is closed.
  • At the end of the batch astro-process a new window pops up headed "Drive error analysis". It contains both a table and a graph of how the photographed image has moved with time.
• Version 9.11.18
  • The problems with the curves to convert from 32-bit accumulator to normal 16-bit image have been corrected. So both at the end of the astro-process and when reloading a .accum (GRIP-format) file, the user is once again presented with the curves dialogue, now working correctly.
  • A new feature is designed to help with that contrast-enhancing curves display for converting the 32-bit accumulator: a new window pops up automatically, containing a multi-channel histogram of the accumulator across the brightness level range that the accumulator currently contains.

  The use of both of the above features is described here.

  I see that Tidal Wave are once again working on jrawio and making good progress. Their latest JAR file (v1.6) does work with GRIP. It only has to be on the classpath declared in GRIP's run.bat file, if you wish to download and try it. Unfortunately they have not yet got the colours right for Canon EOS 5D MkII, but apart from that my latest raw images do load. jrawio is the only third-party software that GRIP uses. It is a set of JAI imageio plug-ins, so no recompilation of GRIP is required.

• Version 9.11.14
  • Star charts are now automatically calibrated as they are created, so that subsequent measurements of distance are in degrees (if the fieldwidth is at least 4 degrees) or minutes of arc (otherwise).
  • If an accumulator is loaded from file (having been saved from a batch astro process) the image is now automatically scaled linearly into 16 bits per channel and displayed. Previously a curves dialogue was offered but there are a number of problems with doing that on 32 bits per channel (as the accumulator has) so it needs further work before it is reinstated.
  • All configuration properties which are paths to files now automatically get "Browse" buttons in the configuration dialogue.
  • Corrected a minor error in which Ctrl+F5 was shown as the short-cut for 2 options in the image table editing menu.
• Version 9.11.8
  • Further small improvements to star charts:
    • Conventional names (eg, Peg 44 eta) are now shown for stars brighter than magnitude 4. (A little XSLT converted the XML described here to a properties file which is now included in the file GRIP.jar. The Hipparcos ids are used as keys for more common names.)
    • Showing Hipparcos variable stars by red boxes on the chart can now be switched off if required.
    • The epoch is shown in the caption bar of the chart. Precession calculation has been improved.
    • The chart image has 8 bits per channel instead of 16, to remove the irritation of converting if it is required to save the chart image in JPEG format.
    • A cross may optionally be drawn at the centre of the chart.
    • The erroneous Hipparcos data for a number of stars with RA and Dec of 0 are ignored if the chart covers the point (0, 0). The log will show any stars removed from the chart for this reason.
  • New operations on the convolutions menu: Gaussian blurring and unsharp mask. The latter is useful for enhancing detail in nebula photos.
• Version 9.10.29
  • The star chart has been improved in several ways:
    • A local stereographic projection is used for the plot (ie, a tangent plane to the celestial sphere at the centre of the plot). This means that any area can now be plotted, even around the poles, and the scale is the same both horizontally and vertically.
    • Stars indicated as variable in the Hipparcos data are marked with a small red square outline in the plot. (I plan to go on to include more variability information from another catalogue linked to the Tycho data.)
    • The epoch field is now used. RA and Dec at a given epoch for the centre of the plot will be converted to epoch 1991.25 for loading the Hipparcos and Tycho data, to find which stars fit in the plot.
    • Clicking near a star that has both Hipparcos and Tycho identifiers will show both.
    • The default chart size is now 800 x 800 so that it displays initially at 100% scale on most screens.
    • The dialogue now enables the user to change the chart size.
• Version 9.10.22
  • A major new option on GRIP's main file menu creates photo-realistic star charts from Hipparcos and Tycho data. This is aimed towards making more useable finder charts for variable star work. Further details.
  • The options on GRIP's main file menu have been rearranged in descending order of their most likely use, departing slightly from normal conventions.
  • At the end of the astro process the resulting image was shown in the image table as having 8 bits per channel when in reality it has 16 bits per channel. This has been corrected by refreshing the table.
  • Any exceptions occurring when an image is saved are now not only recorded in the log files but also shown to the user in a message dialogue that has to be acknowledged. A common irritating case is when trying to save a 16-bit-per-channel image as JPEG. The message ensures the user notices and can try again after using the levels menu to convert the image to 8 bits per channel.
  • For Java programmers: new package net.grelf.astro contains many new classes to do with star charts, such as RA, Dec, SkyPoint, Star and StarChart.
• Version 9.10.14
  • When a star image has been thresholded and then blobs have been detected (see the levels menu), clicking on or near a detected blob opens a magnified view of that blob in a new window. GRIP has had that facility for a long time. What is new is that the small window thus opened has an extra menu, the blob menu. This menu is geared towards estimating unknown star magnitudes (particularly of variable stars) from known reference stars in the same image (ie, the image in which blobs were detected). There is a new page about how to estimate star magnitudes.
  • I can confirm that the memory leak in the astro-process option of the batch menu was indeed fixed in version 9.10.2. I have processed many sets of 64 or more images without running out of memory and therefore having to restart GRIP.
  • For Java programmers: new classes RA and Dec are aimed towards loading reference star data from internet resources in a version of GRIP yet to be released (soon, I hope).
• Version 9.10.2
  • There is a new feature after blob detection on the levels menu, whereby the measured centre, detected outline and its enclosed area and brightness are shown. By putting the brightnesses into a spreadsheet along with known star magnitudes it would be possible to estimate unknown magnitudes of other objects, such as variable stars. It is intended to develop this further.
  • Brightnesses are now always measured as the square root of the sum of the squares of each of the levels in the different channels (eg, red, green, blue) of the image. This produces a better black line on 1-dimensional profiles, more suitable for spectrum analysis (which is also planned for further development).
  • One dimensional profiles now have their horizontal axes annotated in the currently calibrated units for the sampled image (in pixels if it is uncalibrated).
  • The table of images has a new option on the editing menu, for swapping the order of any 2 selected images. This enables any asymmetrical operation on the combination menu (eg, subtraction or division by a flat field) to be applied the other way round.
  • A few things have been tidied on the final image resulting from the batch astro-process, so that it can be reloaded from file after automatic saving.
  • If you select to show detected blobs on every image in pass 1 of the astro-process and you fail to close those windows, the process itself closes them at the start of pass 2.
  • There was a memory leak in the astro process so that if you tried to process a large set of images after having done another large set, the system could run out of memory. This is believed to have been fixed but only after running a lot of time-consuming examples will this be certain. If in doubt, close GRIP and start it again before processing a second large set of images (more than 30, say).
  • There are often warnings in pass 2 of the astro process about converging lists of matches. The cause is still being investigated but no harm seems to occur.
  • The help files have been simplified, for a much smaller download. Previously the whole site was zipped for the help but that was becoming too big. The XSLT that generates the pages has been modified very slightly so it generates two sets of files: (1) for the whole site, which I upload, (2) the help pages and their images only, zipped for you to download. It means that some links in the help pages now go on-line but all of the explanation of menus can be kept with the application by following the instructions for directory layout on the download page.
• Version 9.9.1
  • The astro-process dialogue has a major new facility: radio buttons to specify the image superimposition method to be used.
    1. Warp - GRIP was designed on the premise that simply shifting images to superimpose them would not be good enough because camera and telescope optics always distort images to some extent. If objects have moved from one frame to the next they will not be distorted in exactly the same way. So recognising objects by their mutual patterns and then warping to superimpose them for noise reduction was GRIP's original method of working. This is still the method unless you deliberately select one of the following.
    2. Shift by average - it has become apparent that there are not always enough stars in a telescopic field for the warping algorithm, which really needs at least 9 objects that are matchable throughout the sequence of images. So this simpler method is offered. It finds the average offsets of all objects from one image to another and simply shifts (ie, translates) an image by that average offset for superimposing it on the accumulating image.
    3. Shift by brightest only - in some images (eg, photos of planets) there is really only one large bright object. For this case, GRIP now also offers the simplest possibility: measure the offset of only the brightest object in every image and stack the images using only those shifts.
  • The astro-process dialogue has been enhanced further to include a Help button, giving direct help about this dialogue.
  • The astro-process dialogue now also has a button for viewing the dark image (if any) to verify that a suitable image has been specified.
  • In working with large single objects it became obvious that blob detection was not working properly. It was fine for small objects like stars but not for larger objects such as images of Jupiter. In fact, anyone trying to use GRIP for measuring automatically thresholded objects in general must have realised it just did not work. Blob detection has therefore been reworked so that it is now fully robust.
  • Using test images containing several objects of equal brightness it was realised that only one such object would be kept for measurement. It would be very unlikely for star images to encounter this problem but more generally it would be wrong. This has also been corrected.
    For programmers: the problem is that java.util.TreeSet will not store multiple objects with the same value of whichever field is used for the comparator for sorting, even though other fields may be different and the objects really are distinct. For this reason, all method parameters of type java.util.TreeSet<BlobMeas> have been changed to a new type BlobMeasList which extends java.util.LinkedList. New objects are inserted into the list in sorted order to avoid having a separate sorting step later; this is more efficient with a LinkedList than with an ArrayList. Similarly, all occurences of java.util.TreeSet<Connection> have been changed to use new class ConnectionList. So the API is not backwards compatible, you will need to refactor as just described.
• Version 9.8.23
  • A new option in the batch astro-processing enables the whole process to run automatically and save the results without any intervention. If this option is selected there is no chance to examine GRIP's matching of objects between images, before pass 2 starts, and you are not asked for confirmation of saving the results. If you are confident that the processing will proceed OK (which I am usually) there is then no need to keep an eye on the lengthy processing.
• Version 9.8.17
  • All of the complicated menus now have an additional option at the end for "Help about this menu", to open the relevant help page directly in the default browser.
  • Bug fixed in which the table of opened images could not be displayed if an image had previously failed to open correctly.
  • Bug fixed in setting the (de-)convolution kernel manually or automatically. It is now possible correctly to sample the image to obtain the kernel, either by positioning a square of given half-width or by pointing to a star and detecting its profile automatically. This is particularly useful for deconvolution because the image of a star should be a point but atmospheric and mechanical effects combine to spread it out to the shape actually captured in the image. Deconvolution attempts to restore that shape to a point, for everything in the image.
• Version 9.7.26
  • Convolutions menu has new non-linear filter operations: nearest extreme and rank. Nearest extreme sets every pixel in the image to whichever is nearest in brightness in the user-selected neighbourhood: the minimum or the maximum. The rank filter replaces each pixel by its order in the neighbourhood, scaled so that the highest possible rank will be the maximum level in the image. Both of these filters treat each colour component independently. They are both useful for enhancing detail, particularly in astronomical photos.
  • The window containing the list of currently opened images is now always created when GRIP starts, rather than having to open it manually from GRIP's file menu. It is from this list that images can be combined in various ways; users may not have realised that if they had not opened the list window. Consequently there is no longer a menu option for closing the image list window. Note that the list window can always be found on the screen by first finding the GRIP window (type Ctrl+G) and then choosing File/List on that window's menu.
  • 2 new options on the Combine menu of the image list window: add/multiply images in proportion (eg, 1/4 of first image to 3/4 of second), with a slider to see the effect as the proportion is varied. These are useful for combining the results of image enhancement with their original images.
• Version 9.7.6
  • In gnomonic projection (and its inverse), the lower limit of lens focal length has been changed from 10mm to 5mm, for experimenting on flattening images taken with fish-eye lenses. I have a 15mm fish-eye lens which, on my full-frame Canon EOS 5D MkII gives a 180 degree view along the diagonals of the frame. That produces more barrel-distortion than Photoshop (CS4) can correct, using either the lens distortion filter or the (de-)spherizing filter. But in GRIP, using the inverse gnomonic projection on the Geometry menu and setting 8mm as the lens focal length, I found I could flatten the image. 8mm makes sense because that would be the focal length for the other type of fish-eye lens, that creates a circular view inside the 36x24mm detector frame. GRIP creates a very large resulting image because, unlike Photoshop, it does not crop the results of its filters but makes room to see everything. A consequence was that in 2 Gbytes of RAM I ran out of memory when I tried to save the image on disc, unless I first scaled it down or cropped it. But overall, the process does work - I can use GRIP to flatten images taken with my fish-eye lens. That can be genuinely useful for architectural images where I want to get the maximum possible width of field. Here is a flavour of what can be done:
    Before:
    After:
• Version 9.5.4
  • Major bug fixed in the batch astro process: star detection was not happening if background correction or gnomonic projection were selected.
  • If the batch astro process does not manage to match stars across the images then you now have the option to display a drawing that shows what was detected in each processed image.
  • When performing the batch operation of averaging images, if the first image loaded is raw the user is asked whether to average the images as uninterpreted raw. Previously each was interpreted and then added into the accumulator for averaging.
  • New option on the batch menu: Interpret raw & save as TIFF.
• Version 8.6.28
  • There are two new options on the measurement menu: 2D profile and 3D histogram. The first takes the profile of the whole image and plots it as 3 isometric views, one for each colour channel - you will first need to crop the image to a small enough rectangle (it is intended to make this easier in a later version, selecting a rectangle with the mouse). The second option takes the histogram of the whole image and plots it as 3 graphs - a draughtsman's projection (3rd angle?) of the RGB cube, with frequency plotted on a colour scale that is shown.
  • A new option on the image table/combine menu creates red/green stereo images from a pair of selected images. The selected images must be of the same size and type (number of channels and bits per channel). The resulting image has a monochrome version of the first image in its red channel, a monochrome version of the second image in its green channel and zero in its blue channel. Viewing it through red/green spectacles creates the stereo effect if the original images were of the same scene but the camera moved a few inches horizontally between exposures. It was possible to do this previously in GRIP through a multi-step process but this new option makes it very quick and easy. Cardboard spectacles with a red filter for one eye and a green one for the other are available for a few pence if you search on-line.
  • Options on the levels menu now either work correctly for a monochrome image or display a message saying that the particular operation is not possible on a monochrome image.
  • A small enhancement to Exif.java makes the loading of JPEG images more robust. Some applications seem to save such files with incorrect metadata structures. GRIP now ignores such inconsistencies rather than failing to open the image.
• Version 8.6.11
  • Measurements, including histograms, now work for monochrome images as well as for RGB ones.
  • The curves dialogue now works for monochrome images too.
  • The dialogue for starting the astro process (from the batch menu) has been improved in layout and useability.
  • If the astro process settings require temporary images to be created between passes, a check on available disc space is now done (thanks to new features in Java 6) and a prompt gives time for releasing space if necessary.
• Version 8.2.7
  • The two astro-process options on the batch menu now start with a dialogue for setting various aspects of the process. The dialogue is simply initialised slightly differently for the two options. It is now possible to use any combination of dark and flat fields, histogram background correction and gnomonic projection during the process.
  • The detection of defective pixels and their use in correcting RAW images has been improved. More description is available here.
  • The downloads page now makes available the updated JAR file for GRIP by itself, for those who have already downloaded the full application before. This means a much smaller download for updates (260 kb instead of 1.6 Mb). A diagram is also provided now, to show the required directory structure for running GRIP.
• Version 8.1.21
  • The telescope version of the astro-process on the batch menu now makes use of a flat field image if one is available.
  • The operation of dividing by a flat field image is also available on the image table menu (in the window listing all open images). This enables the action of a flat field image on a single image to be studied, to verify that the flat field image is suitable and that GRIP applies it correctly. (One simple check of GRIP is to clone an image and divide it by the clone, which should produce a completely uniform result.) For more information about the meaning and purpose of a flat field image, see here.
  • The source code for the BatchProcessor class is now available in the downloadable source code, so you can verify its behaviour. Please contact me (graham dot relf at fsmail dot net) if you spot an error or if you can see useful additions I could make.
• Version 8.1.20
  • The astro-process on the batch menu has been improved and split into two options, one for images taken through a camera lens and one for images taken through a telescope without a camera lens. The difference is explained here. Expect further enhancements, to make use of flat field images in telescopic work.
• Version 8.1.13
  • The size (width and height in pixels) of the cells for correcting background levels is now a configurable property. Previously the width and height were always set by dividing the width and height of the image by 16. The cells were not necessarily square, which they are now. The reason for making this configuarable is that very bright objects in a cell can distort the background if the cell size is too small. Likewise large specks of dust on the camera detector causing dark areas can distort the background level. In such cases choose a larger cell size.
  • A bug has been fixed in which cropping a set of images by a batch process failed because the list of files was lost.
• Version 7.11.25
  • The end of the batch astro-process has been improved:
    • The images are now warped onto the middle one in the sequence rather than the first, to give a more symmetrical pattern of overlaps.
    • At the end of pass 2, instead of rather clumsily asking for a list of match trail numbers, the user is invited to draw rectangles intersecting those trails which are to be deleted. Then closing the frame displaying the match diagram causes the process to continue to pass 3.
    • At the end of pass 3 a curves dialogue is displayed so that the read-out from the 32-bits-per-channel image accumulator back into a normal image can be transformed through a look-up curve. This is to enable contrast to be increased and fainter features to be enhanced. Typically a low-value gamma curve would be suitable here. For programmers this means that ImCurveDialogue can now generally transform from either a java.awt.image.BufferedImage or an Accumulator into a BufferedImage.
    • There is no longer a white frame drawn around each image before warping. This is because it could adversely affect the calculation of dynamic range for scaling the accumulated result. Unfortunately the lack of white frames does make it harder to tell where the edge of all the image overlaps falls in the result. Does anyone have a better idea?
  • A new option appears on the levels menu for a RAW image, to automatically detect defective pixels and save a list of them as a CSV file. This option is intended to work on dark-frame images, ie, those captured with the camera lens cap on. NB: THIS OPTION IS STILL EXPERIMENTAL - IT MAY ONLY WORK FOR A CERTAIN RANGE OF EXPOSURE TIMES.
  • A new option on the configuration menu enables a list of defective pixel positions to be loaded from a CSV file. If such a list exists in the configuration, interpreting a RAW image (an option on the levels menu) now takes them into account. This is done by first replacing each of them by the average of its 4 nearest neighbours of the same colour. Bayer interpolation takes place after that step.
  • A less serious (alright, fancy graphics) option has been added to the image menu, to generate a Mandelbrot curve and allow the user to zoom into it repeatedly. For programmers this is in class ImGraphic. It is intended in a future version to add a pseudocolour capability for monochrome images which will make these images even prettier. Meanwhile try splitting channels (levels menu), changing them independently, and recombining (image table menu).
  • A minor bug has been fixed in which nothing happened if no file extension was given for the file name when saving an image in a file. If GRIP did not know what type of image to save it ignored the request but gave no warning that nothing had been saved.
  • A very minor bug has been fixed in which the zoom factor was reported wrongly in the caption of an image frame after saving the image in a file.
  • New class BatchProcessor has been split off from BatchMenu.
  • General refactoring has been done, mainly to simplify menu classes and to make the actions for nearly all menu options available as callable methods in the API.
• Version 7.8.8
  • Two new options (which I needed for a particular photographic project) have been added to the batch menu: Square (multiply by self), for enhancing contrast, and Saturate.
  • Similarly, two new operations are available for making your own multi-step batch process: Square and Saturate.
  • A small bug has been fixed in the dialogue for making your own batch process: a NullPointerException is no longer thrown if the button for adding a step is pressed but then the selection is cancelled.
  • A more serious bug has been fixed in which rectangles drawn for cropping or measuring had to start at top left and be dragged out rightwards and downwards. Not everyone wants to do it that way, so now alternative approaches also work.
  • The calculation of scale and position for newly opened images has been improved so that it looks neater and there is less likely to be an immediate need to zoom or reposition the images.
  • Reading metadata from files has been improved so there is now more likelihood of extracting camera details to include in measurements (eg, if you want to plot a graph against time).
• Version 7.7.4
  • Corrected a very minor problem in which the right- and bottom-most pixels of any image were displayed as black.
  • Added option to the file menu of the image window, for putting a border around the image in any colour. That increases the size of the image by the width of the border on all sides.
• Version 7.5.16
  • GRIP now attempts to read EXIF (ie, camera manufacturer's) metadata from images if the JAI plug-in does not manage to read any when opening an image. This seems to work for JPEG files direct from a camera but may not work for JPEG files which have been saved by an image processing application. Such applications should resave metadata in a non-EXIF format but they do not all agree.
  • Combining images via the image table menu now changes the caption and the history list of the image which contains the result, to make it easier to see which one it is.
• Version 7.5.13
  • The option for opening an image from the main menu has been improved so that several images may be selected at once and opened.
  • A new option on the image levels menu, Average vertically, is for use before measuring profiles along straight lines. This is particularly for spectroscopy. A page about this is planned.
  • A minor bug has been corrected: when opting to rotate or scale an image and then cancelling the dialogue which asks for the angle or factor, the operation is cancelled without throwing an exception.
  • For programmers, new class Timer provides a simple way of logging how long any process takes to run.
• Version 7.4.19
  • The astro process has been improved. After pass 2 it is possible to remove objects from the matching interactively to improve the result. The default value for the number of brightest stars to consider has been increased in the configuration menu from 16 to 24, which seems to spread control points across typical star images better.
• Version 7.4.10
  • A new option on the Measurement menu makes it possible to copy calibration between images, which is appropriate only if the objects being measured were at the same distance from the camera for both images and the same focal length was used.
  • More operations have been made available in the dialogue for making your own batch process.
• Version 7.4.3
  • In certain circumstances it was not possible to save an image in JPEG or TIFF formats. This has been fixed.
• Version 7.3.31
  • A new option on the geometry menu enables an image to be translated by any amount in x and y. Translating by a pixel or two and then subtracting the original image is a way of detecting edges in the direction of the offset. It is then possible to make line drawings from photos by going on to threshold the edge image, then zeroing the image itself (eg, by using the curves option in the levels menu), drawing the overlay into the image, converting to monochrome, inverting and auto-stretching the result. An example of this has been added to the documentation for the geometry menu.
  • The curves dialogue available from the levels menu of each image now has a drop-down for setting some standard curve shapes, including gamma correction curves for user-supplied values of gamma. The V-shaped curve can be used to change subtracted images into absolute-subtracted images (differences all converted to absolute values so the background level can be 0 instead of half-way up the range).
  • Thresholding, also available from the levels menu, now has 3 separate sliders for red, green and blue channels. Thresholding can now be applied in either of two ways: AND-ing the tests on each channel (every channel must be at or above the threshold level) or OR-ing them (any channel may be at or above threshold).
  • Colour balance adjustment is a new option on the levels menu. Each channel can be increased or decreased by a user-selected percentage. Beware when increasing a channel if it already goes up to the maximum level - you will get flattened highlights in that channel.
  • Viewing the kernel on the convolutions menu as an image now provides a menu in the frame, so the kernel image may be manipulated or saved as an image file. Any processing done in this view window will not affect the current kernel however.
  • There was a bug in cloning from the image menu because the file path from which the image had been loaded was not copied to the new frame. Using the reload option on the image menu of the cloned frame would not work. This has been fixed.
  • The batch menu has a new option "Make your own process" but it is not yet complete.
• Version 7.3.25
  • The operations on the convolutions menu have been tested more thoroughly and improved. In particular, deconvolution is now known to work. Try enhancing your blurred photos!
  • The convolutions menu is now explained in these pages.
  • A new option on the geometry menu enables the unused margin of a RAW image to be cropped off. To support this the configuration dialogue has new rows for you to enter the margin values for your particular camera. The margin values may be in your camera's user guide or you can work them out by loading a RAW image and a JPEG image and comparing their sizes from the information option on the image menu.