> It isn't really a "new format". It's an update to the existing format. - It is very backwards compatible. -- Old programs will load new PNGs to the best of their capability. A user will still know "that is a picture of a red apple".
This is great but also has the issue that users might not notice that their setup is giving them a less than optimal result. Of course that is probably still better than not having backwards compatibility.
Edit: Seems the backwards compatibility isn't as great as it could be. Old programs show a washed out image instead which sucks. This should have been avoidable in the same way JPG gain maps work so that you only need updated programs to take advantage of the increased gamut on more-than-sRGB screens and not to correctly show colors that fit into sRGB.
PNG Fourth Edition, which we are working on now, is likely to add gain maps.
However, gain maps are extra data. So there is a trade off.
The reason gain maps didn't make it into Third Edition is it isn't yet a formal standard. We have a bunch of the work ready to go once their standard launches.
This is great but also has the issue that users might not notice that their setup is giving them a less than optimal result. Of course that is probably still better than not having backwards compatibility.
Edit: Seems the backwards compatibility isn't as great as it could be. Old programs show a washed out image instead which sucks. This should have been avoidable in the same way JPG gain maps work so that you only need updated programs to take advantage of the increased gamut on more-than-sRGB screens and not to correctly show colors that fit into sRGB.