http://gram.eng.uci.edu/~jmeyer/

#1 75,045 color

#2 63,618 grayscale

#3 96,255 b&w

#4 109,086 posterization (fewer colors per RGB channel)

#5 29,905 brighter (fewer colors)

#6 11,261 blure

why does #6 gives best compression?

compare #4, #5. In the Y channel of the Y Cr Cb model,

most values are near the upper end for #5. (Y stands

for intensity). so the histogram has smaller stuff to

encode (it is less spread than before)

for #6 you are taking advantage of the DCT transformation.

There are 3 algorithms in the JPEG algorithm:

- conversion to Y Cr Cb

- DCT

- Quantization

Each algorithm has different parameters that are controlled by the desired compression ratio in imaging. The KODAK image viewer that you are using, there is a fixed setting for all these parameters.

It would be better to have individual control over all threewe can get better compression.

Now please compare the actual ranking that we found today with what you had in your table.