How do I change the colour of a shadow pass

#1

Hi

I’m compositing a 3d motorbike model into a jpg background image in photoshop cs4.
I’ve made a shadow pass in Maxwell render, but it’s not the colour I need to match the other shadows in the background.
Shadow pass is grey the jpeg shadows are a dull green.
How can I change the colour of the whole shadow including the pixels around the edge where it gradually fades to white, but still have it gradually fading to white.
The best I’ve managed is just to select the outline of the shadow (as accurately as possible), fill that area with one solid colour of green then blur the edge later.
But that defeats the purpose of having an accurate shadow in the first place.

Here’s the shadow map :

Here’s the background image :

#2

not totally sure i understand but…

…it sounds like you could just use the same image as alpha, layer mask or whatever

you should also be able to color that image by putting a color layer above it. color layer doesn’t color the white areas

#3

Hi Creeto

Thanks for the reply.
If I use the shadow map as a new layer then use mutiply, the shadow is the wrong colour.
It doesn’t match the other shadows.
Can you give me more detail on how to add a color layer.
I add a new layer then what next?
I’ve got loads of experience with loads of programs, but I always find adobe programs unfathomable.

This is the shadow map added as a new layer then changed to multiply :

This is the best I’ve managed by filling the shadow with the paintbucket then blurring the edge :

Both of these shadows are no good.
Maxwell explains in the help files how to save the different layers shadow/reflection/alpha e.t.c.
But I can’t find a tutorial that shows you how to put those layers together in photoshop.
I have spent a lot of time searching.

#4

You should use a Layer Mask on your fill layer. Also, use the Burn and Dodge Tools, as well as Blur, to tweak your shadow.

#5

didn’t see SilverCity’s post…at least now you have couple solutions :slight_smile:

i’m very tired but here’s how i’d do it to begin with

the shadow layer is set to :multiply:
the layer above in just a filled layer set to :color:
then i put in two adjustment layers
one brightness/contrast to control…brightness contrast LOL
the other one hue/saturation

now i can control pretty much everything. color, saturation, value

ATTENTION!

most important is to set the mode of the group the :multiply:
a new group mode is always set to : pass through: which affects all underlying layers

also, you might wanna adjust the shadow picture because it’s way to noisy
i this case it’s better with a clean layer

hope this help. now i gotta sleep :slight_smile:

#6

Ahh, actually Creeto, I think your solution is the better one. It saves you from having to create and tweak the layer mask. Hue/Sat. adjustment layer is also helpful to refine your results. Anyway, either way will work for this image.

#7

Thanks guys.

Now I can stop trying to find the answer, which I’ve been doing for the past 3 hours.

Cheers, both your solutions look great.

#8

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