Tone Mapping Vs. Gamma Correction?

[georgep1]

What is the best way to resolve the gamma problem in maya 8.5 and get a good looking realistic image?

So far I have found 3 options, please tell me if they are wrong, and which one is the best way to go:

1. Turn the gamma in the framebuffer part of the render settings to .455 (1/2.2), and apply a gamma correction node to texture files.

2. use the mia_exposure_simple lens shader to tonemap the image

3. use the mia_exposure_simple lens shader to change the gamma by setting it to 2.2 and apply a gamma correction node to texture files.

Another question I have is why is there an option for both tone mapping and gamma correction
in the mia_exposure_simple shader? wouldnt this be fixing the same problem twice?

also, when using options 1 and 3, is it necessary to apply a gamma correction node to image files used as displacement maps and bump maps as well?

[joojaa]

QUOTE(georgep1 @ 04/12/07, 08:10 AM) [snapback]263930[/snapback]
1. Turn the gamma in the framebuffer part of the render settings to .455 (1/2.2), and apply a gamma correction node to texture files.

Well that would only work totally correctly if your textures themselves are lieanrized and youve ungammaed them on input. Remember your getting the flaw 2 times, once going in and onece going out. The 3d light assumes lienear light but yoru images assume some sort of display gamma.

OK now for your 2 other questions, well tonal mapping is different form gamma. gamma is sort of a uniform change but on top of auto exposure our eye has a automatic color corrector that maps the tone to neutral, so if your in room lighted with a light thats horribly yellow (which is almost always you are in light bulbs lightning), your brain corrects the color cast making white white. Off course since the image you show on film or a display dont have this feature because the surrounding lightning and change in cast prevents tis fixing form the brains side.

So the purpose of all this is t correct the image to the way the eye would work, but see the computation your brain does is WAY better than anything humans can code.

[georgep1]

QUOTE
Well that would only work totally correctly if your textures themselves are lieanrized and youve ungammaed them on input. Remember your getting the flaw 2 times, once going in and onece going out. The 3d light assumes lienear light but yoru images assume some sort of display gamma.

alright thanks. let me make sure I am getting this... if I have an image that I wish to use as a texture (that I am assuming already has a gamma of 2.2) I would have to attach the image to some sort of gamma correction node that would linearize my image and then plug that node into say the diffuse slot of a shader? I take it I would still have to do this if I am using a lens shader to correct my gamma instead of the gamma control in the framebuffer section of the render settings.

would I also have to do this with images that I am using as bump maps and displacement maps?

Are there any advantages or disadvantages of correcting the gamma in the render settings rather than using a lens shader?

[joojaa]

QUOTE(georgep1 @ 04/12/07, 12:12 PM) [snapback]263939[/snapback]
would I also have to do this with images that I am using as bump maps and displacement maps?

no they are already assumed linear. (the purpose of gama correction is to how the nonlinearity of your imaging device as linear), so your result eiether allready has a bug or you've included it in the work flow.