Differences in pixel values will be very difficult to see. The result enhances the contrast of the original image. 219-220 for further discussion of this transformation. The transformation requires that all graylevel values in the input image be equal to or greater than zero. The transformation requires that all graylevel values in the input image be in the range .
Parameters are the three input images.
Each image is chosen from a pop-up menu that lists all images currently open. BIL command is useful for composing three images into a color composite. Real command converts an input image in complex format to two images in real format. FHT command into its separate components for further processing. Both images default to the image in the frontmost window.