pngcheck verifies the integrity of PNG, JNG, and MNG files (by
checking the internal 32-bit CRCs [checksums] and decompressing
the image data); it can optionally dump almost all of the chunk-level
information in the image in human-readable form. For example, it
can be used to print the basic statistics about an image (dimensions,
bit depth, etc.); to list the color and transparency info in its
palette (assuming it has one); or to extract the embedded text
annotations. This is a command-line program with batch capabilities.