PNG

PNG file format

Gamma Problem Saving PNG out of Photoshop

Source: Yves Poissant addressed problems saving PNG from Photoshop a couple of years ago. It seems Photoshop (and perhaps other programs) sets the gamma of png images in some strange way. I think on Windows, the gamma is set to 2.2. Yves suggested removing the gamma information altogether using a program like PngCrush ( http://pmt.sourceforge.net/pngcrush/ ).

You can also use IrfanView to gamma correct a png image. Open the image in IrfanView and go to Image > Color Corrections. Then set "Gamma Correction" to 1.00.

You can also Batch correct a bunch of png images at once. Open IrfanView and go to Fle > batch Conversion. For "Output Format", choose "png". Then hit the "Advanced" button. Then check the box for "Gamma Correction" and enter a value. http://www.irfanview.com/

The problem is more widespread in the web browser arena. Here is a brief overview of the problem web browsers have with correctly rendering png images. http://morris-photographics.com/photoshop/articles/png-gamma.html

Transparency, decals, and PNG files

PNG files with transparency sometimes do not render correctly. TGA files work fine.