Reducing Bit Depth and Optimizing PNGs for the Web
Retrobatch comes built in with a great PNG compressor. When using the Write Images node and PNG is selected as the file type, check the 'crush' option. To obtain greater PNG bit depth reduction, use the Indexed PNG node.
With the Indexed PNG options, PNG image color palettes can be reduced from millions of colors down to 512, 256, or even lower. And after checking the 'dither' option it will be difficult to tell any difference between the original and the Indexed PNG version. Take the following example below.
Processed with Retrobatch + PNG Crush, 310KB
Processed with Indexed PNG, 121KB
There are two images, the one on the left is processed by Retrobatch + the built in PNG Crush, and the one on the right is processed by Indexed PNG node. The Indexed PNG version has its colors reduced to 256 and the file is 2.5 times smaller! That's a huge space savings with no noticeable difference between the two images.
Run Retrobatch against your existing PNG images to see what it can do.