CS420 Fall 2004 Homework, HW 8 (Week 9): Examining Losses in Lossless Compression
a) Find or create a small photographic (not computer generated rendering) jpeg file containing both bright images and shadows. Use mspaint or other program to save this file as a 24bit bmp file. Use brightenbmp to brighten the bmp version of the jpeg file until compression artifacts are exposed. mspaint maybe used to view the results.
b) Describe the compression artifacts found. (if compression artifacts do not become apparent it may be necessary to begin with a jpeg file compressed using a higher compression/lower quality setting)
a) Find or create a small photographic origin uncompressed or lightly compress jpeg file (lightly compressed the uncompressed image). Create a more highly compressed jpeg version of this file. Convert the ‘original’ and more highly compressed files to 24bit bmp and use delta to create a differenced image. Any non-black pixel represents a change. brightenbmp may be used to make changes more obvious (unchanged pixels will remain black even if multiplied…)
NOTE: Original image used should be jpeg encoded since jpeg will convert an input file’s dimensions to an even multiple of 8.
b) Describe the differences.
a) Text file describing answers to 3b, 4b (please identify the image files used)
b) All source code
c) brightenbmp.exe, and deltabmp.exe
d) All image files