24. Compare the size of an all-white image in JPEG format with a
typical photographic image of the same dimensions. At what stage
or stages of the JPEG compression process does the white image
become smaller than the photographic image?
For the next three exercises, the utilities cjpeg and djpeg
may be useful and can be obtained from http://www.ijg.org/. Other
JPEG conversion utilities can also be used. For manual creation
and examination of graphics files, the pgm portable grayscale
format is recommended; see the Unix pgm(5)/ppm(5) man
pages.