Combines three McIDAS frames into a single 24-bit image.
COMBINE window f1 f2 f3 [keywords]
COMBINE combines three McIDAS frames into a single 24-bit image. The output image is composed of the red component of the first frame (f1) and its associated graphics, the green component of the second frame (f2) and its associated graphics, and the blue component of the third frame (f3) and its associated graphics. Since only a single color component is used from each of the three frames, you should carefully select which colors you use in image enhancements and graphics on those frames. For example, if a magenta map is placed on the second frame (f2), it will be black in the COMBINE output image because magenta has no green component (it consists entirely of red and blue).
If you're on a 24-bit display, you can use VIEW=YES (the default) to create a combined window that displays the image. The new window has combine window n on its title bar, where n is the number specified in the window parameter. If you're not on a 24-bit display or you are running a script, you can use VIEW=NO to create and store the 24-bit image in memory. Then, use the FRMSAVE command to save the image in a JPEG or PPM format file.
If you use VIEW=YES (the default), the COMBINE window will be the size of frame 1, regardless of the size of the three frames specified in parameters f1, f2 and f3. If you specify VIEW=NO, the COMBINE window will be the size of the largest frame among the three specified in parameters f1, f2 and f3.
Image frames and graphics frames are "associated" once they have been viewed together. Sessions without independent graphics automatically associate each image frame with the graphics frame of the same number once the frame has been displayed. However, sessions with independent graphics have separate control (and display) of image and graphics frames so image frames are not necessarily associated with the graphics frames of the same number. For example, if you loop through image frames 1-3 while displaying graphics frame 1, all three of the image frames are associated with graphics frame 1. This is relevant because the 24-bit image that COMBINE outputs includes the graphics frames associated with the image frames specified in f1, f2, and f3.
COMBINE 0 1 2 3
This entry combines the red, green and blue components of the data displayed in image frames 1, 2, and 3 and their associated graphics frames into a 24-bit image. The 24-bit image is displayed in a separate window and labeled combine window 0 on the display.
COMBINE 9 14 12 13 VIEW=NO
This entry combines the red, green and blue components of the data displayed in image frames 14, 12, and 13 and their associated graphics frames into a 24-bit image. The 24-bit image is not displayed, but it can be saved to a JPEG or PPM format file with the FRMSAVE command.