Gamma Tutorial Beta

[Sawyer]

I wrote a quick explination of this gamma stuff. I don't know if it's inclusive of everythin (not even sure I want it to be). I thought this may be of help but I want to hear from others to see if anyone finds it helpful or not and if their are things I need to mention or I got wrong. Anyway if you want to look it over its at my ftp site

http://sfrendering.com/index-login.html

login is vray. If it's useful I will take it further if not I will trash it.

[beestee]

It is a good summary of all the bits and pieces in a concise form. The illustrations would seem to help someone troubleshoot their own process. From my viewpoint it is an excellent document.

[Sawyer]

Thanks beestee

[Sawyer]

Slight updates. I will leave it alone for a while.

[Dman3d]

For the gamma color mapping method should the bright be .4545 (1/2.2)?

[Sawyer]

And yes it is I have changed it.

[kimgar]

yeah sawyer! good job!

been looking for a quick rundown of the basics of this mystery
will print and study

thanks!

[panthon]

I think u can still use your solution number 1 with EXR 32 bit. The image is indeed corrected twice as you say, and when u open it in photoshop, it looks washed out. But then, u must use the exposure control to put gamma back to 2.2. This way the image looks the same as inside 3dsmax as u were working with it without having to use the color correction curve in vrayframebuffer.

[tct70]

Sawyer,

Firstly I think a tutorial is a fab idea............I've been using Vray for about a year now and I'm sure I'm not the only one who has read some of the threads regarding this subject and felt like Bambi on ice........!

Couple of things I'd like to ask..........excuse my lack understanding:

1: Your tut starts by explaining the CRT monitors son't display colours correctly. I have two LCD's and images look different between the two! Will gamma correction still apply with LCD monitors?

2: Not sure what you mean about correcting colour swatches. What does the plug-in do, is it necessary, and will it work with Viz?

Hope I'm not bugging you too much, but if you feel this method lets you work quicker I don't want to miss out!

Thanks,


Trev

[beestee]

I noticed one thing. You specify the "Dark" multiplier to be set at 1/gamma for the gamma correction color mapping, but I have to use the "Bright" multiplier to get the same results. I am using Vray 1.47.03 if it makes a difference.

[panthon]

I noticed one thing. You specify the "Dark" multiplier to be set at 1/gamma for the gamma correction color mapping, but I have to use the "Bright" multiplier to get the same results. I am using Vray 1.47.03 if it makes a difference.

He has corrected it, it was a mistake.

[cecil gittens]

good tut, but i notice that you said that input gamma should be set to 2.2 but reading through Vlado piece i can across this

Leave input and output bitmap gamma to 1.0

Cecil

[Sawyer]

good tut, but i notice that you said that input gamma should be set to 2.2 but reading through Vlado piece i can across this

Leave input and output bitmap gamma to 1.0

Cecil

Ok. My aim was to make a simple analogy with the ps levels. I thought that would help and I wanted to keep it simple. I have thought of adding something like this:

Final note: After a while of working this way you may be able to remove the Bitmap Files/ Input Gamma 2.2 from Preferences and take it back down to 1. In order to do this you need to apply the correction to the bitmap files in PS.

I don't know if I want something that addresses every aspect of this issue. There are so many people who can do that better. Ultimatly I just want to de-mystify the process. When I first read about this on that first thread so long ago I thought this was akin to genetically altering the images DNA. It was that confusing. Then it became clearer that this was just a simple image "global" correction and then to compensate you remove the correction locally from the materials. Thats it. That is how I understand it and to me that seems simple. There is so much that is not simple about this and I rely on others for info. I want people to read throbs original tutorial because he wrote it really well and I could only cut/paste. I have nothing to add to that.

To me part of the confusion has been forums. I want a document that can be refered back to. I am in no way discrediting a forum I learn daily from these forums but to me it has been invaluable to be able to find a fixed document and go back to that. Some of these post have gone on for years and I forgot points and often clarity has been lost.

That said I still do like an open source idea where if someone wanted they could add info that I left out. It has been comment on 2 times that I misspoke about HDRI images. I called them high res images. They are not and if I don't correct that it will be confusing. So I am correcting this and their may be pertinent info that I don't include. Some of it may be for brevity and some of it may be for ignorance.

Anyway please let me know what works and what doesn't. I kind of like the idea of a word doc that way you can add on information that you think is important and keep it as a personal reference.

Let me also be really clear if this is confusing if what I write is not helpful or just increases everyones frustration I will remove this. The last thing I want is to add to the confusion.

[panthon]

What about a camtasia videotutorial showing the simple steps?
It would be useful for most of the people...

[Sawyer]

I agree that would be camtastic but not going to happen now.