White balance and the Physical Camera

[InTheCity]

I'll try to cover as many of these as humanly possible over the next few months.



http://www.project1media.com/vray/whitebalance.jpg

If somebody would like to include the reason why the 'White balance' is setup to work the way it does, your two cents would be appreciated. Although I'm comfortable explaining technique, my thoughts on the 'render theory' would likely be incorrect.

Thanks

The final version of this scene can be viewed here;


http://www.project1media.com/vray/scene1.jpg

[choppir]

awesome!!

[afternooncoffeeboy]

great tip, thanks mate

[stefan]

the color you choose in white balance will be taken to be 255 255 255 white.
the whole colorspactrum will be shifted to adjust this in the image.

so if the white balance is set to 255 255 255 nothing changes, this is default.

when you image is too blue or too yellow cause the use of lights or hdris you can set the colro that should be white. so if you have a yellow shift for indoors p.e. you can pick a point that should be white and see its color(in psd p.e.). this color you can set in the white balance. when you render then the yellow shift is gone.

like a real camera( most do it automatly, pro cameras can adjust this manual)

cheers
stefan

[Ernest Burden]

the color you choose in white balance will be taken to be 255 255 255 white....

like a real camera

Like a real digital camera. Film cameras would need filters to adjust color tints, and do not bring values up to pure white.

[stefan]

yes sorry, i meant digital of course.you are right Earnest.
cheers
stefan

[nutriman]

so, this seems to be a nice feature
but is it of any advantage compared to doing it in postprocessing?
excuse my vray noobiness...

[sketchbook]

i was wondering the same thing.

i use white balance when importing raw photos from my digital camera, however i am not sure on changing white balance on a non-raw image. if i render in 32 bit will this be something that can be adjusted in white balance?

thanks ITC

[stefan]

it happens in much high dynamic wider range internal.
so it is actually really much better than in post yes.
but of course you can do that similar afterwards.

cheers
stefan

[Ernest Burden]

i use white balance when importing raw photos from my digital camera, however i am not sure on changing white balance on a non-raw image. if i render in 32 bit will this be something that can be adjusted in white balance?

You can do that adjustment in any image, regardless of bit depth. The problems come in when you do a lot of adjusting to images of 8bit per channel. What happens is that when Photoshop re-maps the colors (really grayscale gradients in each color channel) it cannot fit exactly into the 256 value range, so some rounding up or rounding down of the values results in 'clumps' which is visible as banding. When starting with 16bit/channel or 32bit/channel images you have a much broader numerical range in which to re-map the color numbers giving a much more natural-looking result. In fact, a floating-point image would never be subject to rounding up or down, so that's best, but not necessary.

However, if you insist on working in high-bit all the time, you lose a lot of tools and filters from Photoshop. So the best advice is to do major adjustments (levels, curves, white-point compensations, color-profile biasing) in 16bit, then go down to 8 bit for filtering and tweeking. If you can stay in 16bit then do, but its not always practical.

[InTheCity]

[quote=sketchbook]So the best advice is to do major adjustments (levels, curves, white-point compensations, color-profile biasing) in 16bit, then go down to 8 bit for filtering and tweeking. If you can stay in 16bit then do, but its not always practical.

Wouldn't you agree it's best to achieve as much as possible while still in the 3d environment, as my slightly misinformed tutorial might suggest.

I feel it's impractical to get bogged down with too many changes and imperfections in post, if you can get close to what you're after from a well balanced scene.

[stefan]

yes all is best done in the application. vray and c4d render with i think 128bit per channel....

thats why all this tools are in.
cheers
stefan

[kamelvfc4d]

great work in experiment thanks