Details of Figure 4
Pixel values at inside left corner of the letter A: Left: Original; Center: Minimum Compression. Values 209-243 (the highest value in the image) have been replaced by 229 and values 143-185 by 162 (143 is the lowest value in the image). The remaining values have been replaced by 199; Right: Maximum Compression. The intermediate (anti-aliasing) value 199 has been replaced by 229.