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View Full Version : what about gamma correction in max?


eathquaketry
06-10-2010, 03:33 PM
I worked with max & V_ray for about 2 years and didnot know what is that gamma correction but i heard from some experienced guy that i should always turn gamma correction ON and somehow i am ok with that and did so but after i did i found that the rendered image i saved is differnet from the one i got from V_ray inside max i mean the colors changes outside max.
So please i want something to explain what is gamma correction in details because i have a feeling that it will change the renderd image very much if i got it right.
and what most people do, do you keep it turned off or on???

thanks for your time.

Daniel-B
06-10-2010, 08:58 PM
This tutorial explains it pretty well.

Part 1
http://www.aversis.be/tutorials/vray/essential_gamma_01.htm

Part 2
http://www.aversis.be/tutorials/vray/essential_gamma_02.htm

Part 3
http://www.aversis.be/tutorials/vray/essential_gamma_03.htm

sundialsvc4
06-18-2010, 09:55 PM
I found this page at djx.com to be useful:

http://www.djx.com.au/blog/2008/09/13/linear-workflow-and-gamma/

... and what was most useful about it was the several links to other articles, which appears at the top section of that page.

I recently spent way too much time wrapping my head around this issue as it specifically applies to the software that I use (Blender), which only in its most-current (2.5-A2, for you Blenderheads out there) release has a "color management" checkbox to help deal with the issue in many cases. Still, it was beneficial to understand why the issue exists and to get some rules-of-thumb (e.g. to understand what "nifty little checkboxes" like this one actually do and when they do it. You might still have to intervene from time to time.)

I finally stumbled upon this rune: if you are "looking at it on your screen" (or on paper) and "it looks right," then you must be looking at digital data that has had a gamma-curve applied to it, because your screen is designed to display gamma-adjusted image data. That gamma-adjustment might be a permanent part of the data in the image-file (as is the case with a digital photo taken in any mode other than "raw"), or the remapping might be being applied on-the-fly. You need to clearly understand when, and where, this is being done ... and do not rely too much on "check it and forget it."

You need to know this because you always must know what you are looking at. ("Is it, or isn't it?")

Your renders need to operate in a nice world where "1 + 1 = 2." Anything going into that world (including color values that you "picked by eye") must be reverse-gamma mapped so that it becomes linear. (If your package magically does that for you, "cool!" If not, you have to.) Do all your rendering magic in that wonderful easy linear world where "everything adds up nicely," then gamma-map again before it pops out onto your screen (or as the case may be, make sure that your CG package is doing so for you). It makes a huge difference and is worth every fraction of a second you may spend wrapping your head around it.

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06-18-2010, 09:55 PM
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