Reinhard color mapping in PS and After effect: how?

Common Common :: Render Theory
1

Hi guy

have a problem. Usually, when i work on VRay, i use Linear Work Flow. I work in linear + sRGB button. When i produce my .exr float render in linear mode, out of VRay and 3ds max they are dark, but i change the gamma in PS ( femous 2.2) . Now, if i work in Reinhard mode, how i can obtain the same result in PS? In Photoshop i have only 3 tool (Exposure, offset and Gamma correction) but i can’t obtain the same Reinhard result.

Can you hel me?

Thank’s

cecofuli

2

I think you can adjust the brightness curves in Photoshop in a way to resemble the Reinhard curve.

Best regards,
Vlado

3

The big shiny and beautiful bubble of HDR workflow in PS bursts when you discover, that there is no curves control in 32 bit mode…

Best regards,
A.

4

Agreed,

Once we switched to mostly using a floating point image
workflow PS was out and Combustion was in.

Regards
Bri

5

Hi guy,

Ah, ok, there isn’t “mathematical” and accurate solution. But i see that playing in 32bit with the 3 tools, i can obtain near the same result than rainhard.

Thank’s! :slight_smile:

cecofuli

6

Why u try to reproduce it in PS, when u can set it in Vray ? I use renhard color maping in Vray all the time, and is mutch more suitable for me, than try to reproduce it in PS..

7

Hi
Becouse i prefer work in linear space 32bit float number, with not embeded color mapping and apply my corection only in POST (PS for Still and AE for movie). :slight_smile:

Bye

cecofuli

8

Hi Users,

I am interested in applying the color mapping curves after rendering in linear spaces. Does anyone know the mathematical functions for doing color mappings like:

-Exponential
-HSV-Exponential
-Intensity Exponential
-Reinhard?

I would like to write me a script in Maxscript that allows me to get a preview of a preselection of different color mappings after the image is rendered in linear space.
Any help? I could provide you with the script once I have done it.

Thanks :slight_smile:

Robert

9

Here are the forumlas for these color mapping modes:

Exponential:

float k=clamp(color.intensity(), 0.0f, 1.0f);
k=darkMult*(1.0f-k)+brightMult*k;
res=color;
res.clampMin();
res.set(1.0f-expf(-res.r*k), 1.0f-expf(-res.g*k), 1.0f-expf(-res.b*k));

HSV exponential:```
float k=clamp(color.intensity(), 0.0f, 1.0f);
k=darkMult*(1.0f-k)+brightMult*k;
res=color;
res.clampMin();

float h, s, v;
RGBtoHSV(res, h, s, v);

v=1.0f-expf(-v*k);

res=HSVtoRGB(h, s, v);


Intensity exponential:```
float k=clamp(color.intensity(), 0.0f, 1.0f);
k=darkMult*(1.0f-k)+brightMult*k;

float c=color.intensity();
float m=(1.0f-expf(-c*k))/c;
res=color*m;

Reinhard:```
res=colormultiplier;
res=res(Color(1.0f, 1.0f, 1.0f)+res*VR::sqr(burnValue))/(Color(1.0f, 1.0f, 1.0f)+res);


Best regards,
Vlado
10

Thank you Vlado, that is great!

Cheers

Robert

11

Does anyone know how I can get read out the 32bit-pixel value of an hdr image in maxscript? Max is giving me out the 8bit-rgb-value with the getPixels-function, even if it is an hdr image. Or is there any function in the vray sdk that does this?