Defining a Composite Image

Figure 22: An Example of a COMPOSITE Image

It is often useful to display a whole series of images together. This can be achieved in a very general manner using the COMPOSITE command. An example of such a composite image is shown in Figure 22. The files containing the data are defined as explained above. In addition a graphic form allows, a number of options:

SUBTRACT: Allows a background image to be input from file and subtracted from each image input in the series, prior to further operations.

ROI: Allows interactive graphical selection of a small region to be input and used to built up the composite image. If ROI is not selected the whole of the input images is used.

INCREMENT: Increment number between input files (see above).

NO. PER ROW: Number of input images to be displayed together on one row of the composite image. The number of rows is calculated automatically from the number of files and the number per row.

RE-BIN NO.: This is the factor by which the input image pixels should be re-binned (in both directions) before being assembled into the composite image. If many images are being input fully it is recommended to re-bin them to reduce the computer memory requirements.

If SUBTRACT is YES then the file selection tool will help you input an image to be subtracted from each of the file series images. The file format must be the same.

If ROI is YES the ``FIT2D: REGION OF INTEREST MENU'' will appear. The ZOOM IN button can be used to select a sub-region. Coordinates of the region may be entered graphically, or by clicking the KEYBOARD button and entered from the keyboard. The other buttons allow un-zooming, if the original choice was not correct. When satisfied click on the EXIT button.

If the size of the data array needed to construct the composite image is larger in either dimension than the current program array sizes, then you will be prompted DESTROY AND CREATE BIGGER PROGRAM ARRAYS. If you answer YES any current data and ``memory'' data will be lost, and the program array sizes will be set exactly to the size necessary for the composite image. Entering NO will abort the operation. Assuming the computer memory is available the operation will start inputting data, otherwise an error message will appear.

When the data has been input, the composite image is displayed as a false colour image. The data is in the main program array, so operations such as DISPLAY may be used to change the display style. The FILE SERIES menu can also be exited, and the data can be analysed within another interface.