in news:41a8bf51$1@news.povray.org William Pokorny wrote:

> Cool. So we can be reasonably sure Brigitte's scene file has an
> assumed_gamma statement other than 1.0 or that her image_map jpg
> specifies a gamma correction. [...]

No.

If an image looks fine in an imageviewer on a 'gamma 2.2' monitor, you 
can be sure that a gamma correction is applied to it. An image with a 
gamma of 1 would look dark on that monitor.

Now if we take that gamma 2.2 image and use it as an imagemap in POV-Ray 
it will look to bright if the scene is rendered to a gamma of 2.2. The 
gamma correction is now applied twice to the initial image. If the scene 
were renderd to a linear gamma, the image map would look right. Brigitte 
can try this by removing the line 'assumed_gamma = 1' from her scene.

To use images for imagemaps, you have to convert them to a linear gamma 
(gamma=1).


Ingo

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