lightpasses too bright?

[whersmy]

I think I`m doing something wrong, but I can`t get two passes to combine properly like it should according to the how-to: http://render.otoy.com/forum/viewtopic.php?f=51&t=44350
in PS i have:
1 ambient pass
1 lightpass

when adding linear dodge the image becomes too bright, i need to change the fill value for correction?
i saved out 16-bit pngs and kernel with PT

[stratified]

Hi,

What are your imager settings? You need to make sure you are working in linear color space. Can you try to set your gamma to 1 and the response to Linear/off? This should add up in post (you need to gamma correct the image in Photoshop afterwards because otherwise it will look too dark.).

cheers,
Thomas

[whersmy]

changed the gamma to 1 in standalone + linear response, it get`s better, but it`s too bright when combining them in ps (cs4)
do i need to change exposure to 2.2 in standalone?

[prodviz]

Use 'Screen' blending mode on 16bit images. Use 'Add' on 32bit.

[whersmy]

yep that does the trick! thanks!

[whersmy]

hi stratified,

Does changing the opacity in post of an extra lightpass equal more or less physically correct changing the power of a lightsource?
i`ve been looking into this and it kind of works to tweak / balance light, im just not sure if it`s physically correct

cheers

[stratified]

hi stratified,

Does changing the opacity in post of an extra lightpass equal more or less physically correct changing the power of a lightsource?
i`ve been looking into this and it kind of works to tweak / balance light, im just not sure if it`s physically correct

cheers

The formula is total light = C1 * L1 + C2 * L2 + ... + Csun * Lsun + Cambient * Lambient. Tweaking Ci modifies the power of the light. But I don't think you need to change the opacity of the layer (maybe I'm wrong). I will have to try later with PS but I tried this experiment in Blender and there I had to use the gain on the color correction node.

cheers,
Thomas