I would like to start using pngquant library in our product to improve our custom png compression. But png quant is lossy and it is going to be a hard sell. The main objection that I will get is we can't loose colors/quality. Are there any samples/cases when png quant algorithm produces compressed png images with visible loss in quality?
I found that loss is noticeable when gradients with wide range of colors is used. http://the-coderok.azurewebsites.net/2015/09/23/Example-of-noticable-loss-in-image-quality-that-was-compressed-with-PNG-quant/