mohanagy / pnginfo

Describe PNG images

pnginfo

The pnginfo utility explores the content of PNG files.

Contents

1. Install
2. Instructions
3. License

Install

Requires

• C compiler ;

Build

$ ./configure
$ make
# make install

Instructions

It is possible to list the chunks in a given PNG file or to request the content of a specific chunk.

Examples:

$ pnginfo -l -f lena.png 
IHDR
sRGB
IDAT
IEND
$ pnginfo -c IHDR -f lena.png
IHDR: width: 512
IHDR: height: 512
IHDR: bitdepth: 8
IHDR: colourtype: truecolour
IHDR: compression: deflate
IHDR: filter: adaptive
IHDR: interlace method: standard
$ pnginfo -c sRGB -f lena.png
sRGB: rendering intent: perceptual

Only the following chunks are implemented right now:

• IHDR ;
• PLTE ;
• tRNS ;
• IEND ;
• cHRM ;
• gAMA ;
• sBIT ;
• sRGB ;
• tEXt ;
• bKGD ;
• hIST ;
• pHYs ;
• sPLT ;
• tIME.

Chunks that are not part of the 2003 PNG specification, either because they are custom made or part of an extension, are still listed but can't be queried.

The -s option can be handy if garbage is placed at the begining of a file. pnginfo -s will try to skip said garbage until it finds an acceptable PNG signature.

License

All the code is licensed under the ISC License. It's free, not GPLed !