An Introduction to Game Design: Concepts, Multimedia, and Using Scene Builder - Beginning Java 8 Games Development - page 168

Figure 5-3 . A truecolor PNG24 image created with Autodesk 3ds Max, which you are going to compress as PNG5
Interestingly, it is permissible to use less than the 256 -colormaximum in an 8-bit
indexed color image. This is often done to reduce further the imagery's data footprint.
For instance, an image that can attain good results using only 32 colors is actually a
5-bit image and would technically be called a PNG5, even though the format itself is
generally called PNG8 for the indexed color usage level.
I have set this indexed color PNG image, shown in Figure 5-4 , to use 5-bit color
(32 color, or PNG5) to illustrate this dithering effect clearly. As you can see in the im-
age preview area, on the left-hand side of the figure, the dithering algorithm makes dot
patterns between adjacent colors to create additional colors.