"Warp" <war### [at] tagpovrayorg> wrote in message 
news:45081201@news.povray.org...

>  The problem is not with the gamma value in a PNG. The problem is that
> PNG *has* support for gamma value. Other formats don't have this problem
> because they don't have gamma support at all.

Thanks, Warp.  Your explanation has helped me see much more clearly.

So, according to the docs, then, POV-Ray stores the gamma value as 
1.0/display_gamma.  It also says "PNG is the only one that has any gamma 
correction features and is therefore preferred for images that will be 
displayed on a wide variety of platforms."  Isn't this somewhat misleading? 
PNG is the preferred format (in part) because it has the capability of 
storing gamma values, but not because PNG can be displayed on a wide variety 
of platforms.  Most likely, PNGs will be displayed with many differences 
across platforms/programs compared to another image format that doesn't 
contain gamma information.  In order to have an image created in POV show up 
most consistently (as opposed to 'correctly') across platforms, PNG is not 
the best choice.

I'm not complaining, I'm just making sure I understand (from a user 
perspective).  If I want my image to display as I intended it, I should use 
PNG, and blame the program (browser, etc.) if it doesn't implement PNG gamma 
support properly.  On the other hand, if I want to be sure my image is 
displayed as consistently as possible, regardless of the program used to 
view it, I should opt for some other image format, and complain quietly to 
myself that I don't get to store the gamma info as I want.

- How

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