pngcheck binary package in Ubuntu Focal amd64

 pngcheck verifies the integrity of PNG, JNG and MNG files (by checking the
 internal 32-bit CRCs or checksums) and optionally dumps almost all of the
 chunk-level information in the image in human-readable form. For example, it
 can be used to print the basic stats about an image (dimensions, bit depth,
 etc.); to list the color and transparency info in its palette; or to extract
 the embedded text annotations. All PNG and JNG chunks are supported, plus
 almost all MNG chunks (everything but PAST, DISC, tERm, DROP, DBYK, and
 ORDR). This is a command-line program with batch capabilities (e.g.,
 pngcheck *.png).
 .
 Also includes pngsplit which can split a PNG, MNG or JNG file into
 individual, numbered chunks.

Source package