I tried using the PNGOUT plugin to convert a 16-bit png to 8-bit png, but it will only save to 16-bit. I set option bit-depth = 8. I need a 8-bit png with alpha transparancy so the "save for web" feature is no good. Is it possible to do this via pngout at all?
Awesoken at
Re: Convert 16-bit png to 8-bit png
Not like it matters, but which plugin are you talking about? Irfanview or Photoshop?
PNGOUT does not handle bit depth 16 at all. The 8-bit bit depth option is only used for the grayscale (/c0) and palette (/c3) modes. The only way this could work with PNGOUT is if the image was first downsampled before being sent to the compression library - and that would not be my code that does that.
If you want to compress your 16-bit PNG, I suggest downsampling to 8-bit using a different utility first, and then running PNGOUT.
captainfreedom at
Okay. I am looking at a program called pngqn to do this.