Gamma Correction

[maryam]

Hi Dear all,

i have rendered a scene with two colormapping,

Gamma correction & Exponential.

i got the better lightening from exponential than gamma correction.but i had my window frame washed out.

the gamma seems too gray, specially on brown wood & red stone i dont like it.

i use gamma correction: 0.4547 for dark & bright multipliers.environment 8.

exponential:2.66 for dark & bright multiplier.environment 8.

exterior light:one direct light :5.2 multiplier

interior lights:two spot lights without shadow,two vray lights on top of the work tops.under the cupboards.

Any suggestion would be appretiated.

 

what could i do if i want to stick with gamma correction colormapping?

i have seen it works very well for some people but not for me.(zuliban has made a great one "apartmento").

[EricMLevy]

This may help. Recently, I've been saving my files in the OpenEXR format, bringing them into Photoshop, doing Exposure corrections globally and locally in the image, and then converting to 16-bit color space to do additional Photoshop work. This gives you the most control over the exposure of the image, and does not degrade the image like Levels adjustments would.

[Sawyer]

TRy bright 1 dark .4545 with Gamma correction color mapping.

[maryam]

Thanks eric,i will try this method.it seems to be good,especially becoz i dont have to use level adjustments.but i am looking for a way in the max environment,not in the other softwares.especially becoz i want to make an animation.

Thanx sawyer,but i did it ,i am still not happy about the gray tone all over the image.

i did something usefull to fix my problem but it wasnt about colormapping.

i put some dark boxes invisible to camera out of the window,up & down.to decrease indirect lighening on the frame.& set the colormapping to exponential.i got a very good result.

BUT What IS THE BEST WAY IF I WANT TO USE gamma correction?

[EricMLevy]

I've only used gamma correction with scanline (logarithmic exposure control) but it seems similar to VRay's gamma correction. It looks like the exponential gamma control is the way to go for your scene. Maybe you could use a soft falloff omni with a negative intensity near the window to bring down the blown out area. Or you could relight the scene within a more reasonable range of light to dark.

 

If it's blowing out, there's a) too much light at the blown out area b) the exposure control is setup wrong.

[EricMLevy]

Did you try HSV exponential color mapping:

http://www.spot3d.com/vray/help/VRayHelp150beta/examples_gbuffer.htm

[Neelu]

Hey Maryam

 

That is a nice stainless steel texture.

Was wonderning if you could share the params

 

I am working on a scene now and have something close to Stainless steel,but yours looks dead on.

 

 

thanks

Neelima

[maryam]

thanx alot Eric,i agree to you,the setup must be wrong to get some places burned.but that is a very small piece(lol).i want to get rid of it!

actually i havent tried hsv exponential as its my first time gamma correction.i saw the page you suggested hsv exponantial seems to be kind with colors.it is very important to me.i will check that one also.

BUT I STILL dont know what to do with GAMMA CORRECTION!

to NEELU:i will share the mat to this post as soon as my pc finished its current rendering.

[maryam]

here is the mat.hope it would be usefull.

[Neelu]

Hey Maryam

 

Thanks for the stainless steel texture, worked out great.

 

about Gamma correction, and this is just my 2 cents, but what if you use gamma color mapping, maybe you can change the saturation and contrast under the indirect illumination rollout?

 

and as Chris says the best way would be to use color correction with photshop or whatever. you can render animation out in frames and then apply an action to each frame and composite it afterward.

[daniel_zevahc]

If you want to use Gamma correction color mapping with JPG's texture files you need to apply the ColorCorrect plugin to all of them with a gamma of 2.2 so your materials wouldn't' look washed out. Also redo your lighting multipliers.

[maryam]

Thanks guys for your supports.i am sure all of the notes are usefull.to neelu,i already played with saturation & contrast ,but, exponential colormapping & those invisible dark boxes was the last solution!!