GRIP's main menu
When GRIP runs it first displays its main window and a separate window containing a list of currently opened images (initially this list is empty of course). The main window is quite small because it simply contains a menu bar, logo and copyright and version information. If it becomes hidden behind other windows it can easily be brought to the front by typing Ctrl+G (Command+G on Apple) from any other window of GRIP.
NB: Do not be surprised if loading an image in RAW format seems to produce a completely black result. You can verify from the measurement menu that data are in fact present in such cases, though dark because they occupy the lower 12 or 14 bits (depending on camera model) of 16 in each channel (ie, up to only 1/16th or 1/4 of full brightness). The levels menu contains an option for interpreting the raw data of these images. For more details about loading RAW images into GRIP see how to open RAW images.
displays the standard dialogue for selecting multiple files. One or more image files of any of the formats recognised by GRIP can be selected. The images are then loaded into memory and displayed, each in its own window (ImFrame).
- Further details. leads to a dialogue for setting the position and size of a realistic star chart image which can be plotted if you have downloaded the publicly available Hipparcos and Tycho star data.
- displays a small dialogue for setting the required width and height of an image, which is then created and opened in its own window (Java class ImFrame).
- levels menu or the blobs menu and which has the extension .blobs. Such files are special to GRIP and contain information about all objects detected in an image by the "Detect blobs" option on the levels menu. A blob is a contiguous group of (eg, bright) pixels that has been detected but has not yet been identified as, for example, a particular star. A .blobs file also contains a path to the file holding the image in which the blobs were detected, so opening the .blobs file should enable GRIP to open that image too. When the image is then displayed it is in "blob hover" mode so that moving the mouse over it highlights the blob nearest to the cursor. Clicking the mouse in that situation displays a magnified view of the nearest blob, which makes the blobs menu available. Among other things, the blobs menu enables unknown magnitudes of stars to be measured in relation to others in the image. is for opening a file saved from either the
- special window showing a table of all the image windows currently displayed by GRIP. Rows of the table may be selected. Above the table is a menu which enables operations to be performed on the selected images. This is particularly useful for combining images: adding, averaging or subtracting them, or several other interesting things. brings to the front the
- pops up a confirmation dialogue. If you confirm your intention to leave the application, GRIP closes all of its open windows and ends.
The batch menu provides a way of applying the same processing to a sequence of images. GRIP sets no particular limit to the number of images which may be processed (though a limit may be imposed by the system's standard file selection dialogue). The images are not displayed in most of these processes (except for the slide show), to save time, but a progress message is shown while the processing takes place. If the processing results in new saved images they are always given modified names, so the original files are not overwritten.
opens a dialogue for changing various settings. These settings are held in the file grip.properties. This is a standard Java properties files containing the settings as text in the form "name=value". The properties file is loaded when GRIP starts running. The file is recreated if the OK button is clicked to end the properties dialogue.
- levels menu. The list can be created from a dark image - see the levels menu again. allows a CSV file to be opened and a list of defective pixel coordinates to be loaded. The existence of such a list in the configuration causes different behaviour when a RAW image is interpreted, in the
This menu uses the new desktop facilities of Java 6, in the package java.awt.desktop. Selecting any option except the last one (About GRIP) launches your system's default browser in order to display help from HTML files. This mechanism does not work in Java versions earlier than 6.
- displays the Contents page.
- displays the Index page.
- displays programming information in Sun's standard javadoc format. Java programmers can use this to modify and extend GRIP.
- elsewhere, an image is a large amount of data so it is quite possible to run out of memory when several are opened. displays a message window which shows not only the version identifier for this copy of GRIP but also some useful information about the Java Virtual Machine (JVM) in which it is running. The information includes how much memory is currently being used and how much remains available for GRIP to use. It can be interesting to look at this at various stages when opening, closing and processing images. As discussed