On 3/27/2014 9:43 PM, Alain wrote:

>> Hello,
>>
>> I would like to know if there is a way of reading the resulting pixel
>> value in the rendered image as it is being rendered and if it is
>> possible to overwrite it with another value. Possibly based on the
>> original color.
>>
>> This is for testing lighting on a scene. If the color at the pixel is
>> above a certain value it should be marked with another color and would
>> let me know that the image is being saturated with too much light. Not a
>> scientifically rigorous method but it works well for most cases.
>>
>> I can do this manually by just rendering, in EXR or HDR format, the
>> scene using only a simple diffuse white material for all. Then, after
>> rendering, load the render into a high-dynamic image viewer or editor to
>> see if there are any places on the scene that are too bright.
>>
>> I already looked at ImageMagick but it just overkill for what I need.
>>
>>
>>
>> FlyerX
>
> Reading a rendered pixel DURING render? Not possible without patching
> and recompiling.
>
> I can propose some alternatives:
> Render the scene with a lower light level, say, dividing all
> light_source intensity by 10 or some other value.
>
> Have some mirror with a reflection value of 1/8, 1/32 or less showing
> the areas where you suspect are affected by clipping.
>
>
>
> Alain

Thanks for the tip. I think I found an easy way to get an idea of 
saturated colors: rendering in HDR/EXR format with Display_Gamma=0.01. 
Any colors above 1 will still show.

FlyerX

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