The existing HDR in PNG requirements doc lists the 'sRGB' chunk as
lowest priority.
However, the PNG spec [1] says that the 'sRGB' chunk has a higher priority
than 'gAMA' and 'cHRM', as it is short-hand for an exact set of 'gAMA'
and 'cHRM' values.
This commit corrects the priority order of the PNG chunks.
The existing HDR in PNG requirements doc lists the 'sRGB' chunk as lowest priority.
However, the PNG spec [1] says that the 'sRGB' chunk has a higher priority than 'gAMA' and 'cHRM', as it is short-hand for an exact set of 'gAMA' and 'cHRM' values.
This commit corrects the priority order of the PNG chunks.
[1] https://www.w3.org/TR/2003/REC-PNG-20031110/#11sRGB