"stm31415" <sam### [at] cscom> wrote:
> Here is how I understand it - and I may be wrong, it has, astoundingly
> enough, been known to happen ;)
> The gamma info that is included in some images (not this one, as you said,
> it being jpeg) is there specifically to allow for apps to correct the image
> to make it appear as it did on the monitor it was originally made on, i.e.
> yours.

Yes, that's how I understand it as well (though as mentioned, I never render
..png's to send elsewhere, so I haven't seen that "with my own eyes," so to
speak.)  BTW, as you may already know, a .png image (with an embedded gamma
of 1.0) works wonderfully when used as an image_map within POV.  It will
render accurately no matter what the assumed_gamma value of the scene is.
Alas, not so with standard file types like .jpeg or .bmp; then
assumed_gamma must be set to [whatever overall system gamma the image was
created in.] 2.0 in my case.  But a most *incorrect* thing to do, though
(as has been drilled into me by just about everyone.) But I do it anyway...
;-)

> IF there is no such information, then the image is seen in an
> altered state, because the gamma of the viewing monitor is different than
> yours. If I change my monitor's gamma to match yours, that is, I make the
> correction instead of the software, it works the same way.

Right again. But from the many tests I've done, I can honsetly say that the
"altered state" is *minimized* by my use of a 2.0-gamma setup. Of course,
others may disagree.  Mine was simply  practical consideration. But as you
say, to see my image exactly as I had intended, another system would have
to be changed to 2.0 as well.

>If you do not
> plan on my changing my viewing system, then you might as well not do gamma
> correction, make the image look good on your monitor, and accept that it
> will be different on mine.

True, very true.


> So unless you use a filetype that includes gamma, and a program that adjusts
> for it, or make us all switch to gamma of 2.0 (which may be logical but is
> still wierd) then there is no point in using assumed gamma.

Do you mean assumed_gamma in POV?  If so, then...uh...I don't know how to
accurately answer that.  Mainly because I don't yet FULLY understand what
happens when leaving it out. Call me slow, I dunno. I would humbly suggest
taking a look at my original gamma discussion, and the follow-up comments
that have been posted...but swallow a strong headache pill beforehand...
:-)

Ken

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