2.1.3 [W3C-PNG] Section 4.7.2, Chunk types
The remaining 14 chunk types are termed ancillary chunk types, which encoders may generate and decoders may interpret. a. Transparency information: tRNS (see 11.3.2: Transparency information). b. Colour space information: cHRM, gAMA, iCCP, sBIT, sRGB (see 11.3.3: Colour space information).
All Document Modes (All Versions)
gAMA chunks are the only color space information chunks that are supported. No color conversion is applied to the pixel color values that are read from the PNG file.