PNG opening chunk of the PNG PNG (Portable Network Graphics) Specification, Version 1.2 “PNG (Portable Network Graphics) Specification, Version 1.2” Chunk layout PNG Spec http://www.libpng.org/pub/png/spec/1.2/PNG-Structure.html png specification Chunk layout «PNG (Portable Network Graphics) Specification, Version 1.2» “PNG (Portable Network Graphics) Specification, Version 1.2” Chunk layout http://www.libpng.org/pub/png/spec/1.2/PNG-Structure.html four fields Chunk layout PNG Specification "PNG (Portable Network Graphics) Specification, Version 1.2" "PNG (Portable Network Graphics) Specification, Version 1.2" opening chunk of the PNG