pngcheck

pngcheck is a simple, easy to use application designed to verify the integrity of PNG, JNG and MNG files. The check is done by analyzing the internal 32-bit checksums and decompressing the image data, but the results are displayed in human-readable form.

The program comes with several advanced options that can provide in-depth information about the image files. Among these settings you can count printing contents of tEXt chunks, escape chars, the colorized output for ANSI terminals or print contents of PLTE, tRNS, hIST, sPLT and PPLT.

You can use the app to test verbosely and very verbosely, the difference being that in the latter case the program first decodes and afterward, prints the line filters, whereas the first option enables the print of most chunk data. The app permits you to search for PNGs within other files and extract them or test them directly.

The application can come in handy if you need to grab various statistics about a certain images, such as depth, dimensions, colorized output, so on and so forth. The utility can also come in handy when you want to learn more about the transparency levels and colors in the picture, options that are available solely with the colorized images, as you probably hinted already.