Change standard surface base color in a rendering using Photoshop?

[jrw2]

Hello, my task is to create lots, let's say 40, color versions of a product rendering. I have all the colors I want to use in an image file.

One way to do this is to simply create Arnold materials for all color versions and change the base color for each material using the eyedropper tool, then render each color version. However, this will be very time-consuming.

Another idea I'm exploring is to render a single image with AOV's like base color AOV, shadow AOV, specular AOV, etc. Then in Photoshop stack the layers together to recreate the beauty pass and replace the solid color in the base color AOV layer to generate the color versions. This would be a lot faster. However, I cannot find any base color AOV. Also, I'm unable to recreate the beauty AOV using the other AOV layers in Photoshop, everything gets too bright. How can this be achieved?

[lee_griggs]

Tbh, changing the colors of 40 shaders shouldn't take more than half an hour.

Do you have the RGB values of the colors? You could maybe export the shaders, edit the .ass file and then import them back in?

Regarding AOVs, you could change the albedo AOV.

[jrw2]

I would have to read off the RGB values and manually type them in, which would take more time, then there is the rendering time in addition. The Photoshop method looks more efficient. If I use the albedo layer to tweak the color, what other AOV layers should be included, in what order, and what blending mode?

[lee_griggs]

>I would have to read off the RGB values and manually type them in, which would take more time, then there is the rendering time in addition.

Then just create the shaders and change the colors. It shouldn't take more than half an hour to do.

There is a Photoshop compositing example here.

[jrw2]

If this was a one-off project, yes, I could get this to work by creating shaders, but I'm trying to create an efficient workflow for future projects as well. For example, a rendered image could contain five colors that I have to create 20 color variations of.

With the Photoshop method, I figure that I can use replace color on the diffuse layer, so I'm almost there. I've followed the instructions on the link you gave, creating a super simple scene, outputting AOV png's, but the resulting image is much brighter than the beauty pass.

Beauty pass:

AOV' blended together in Photoshop:

What is going wrong here?

[peter_horvath]

It is recommended to render the AOVs in OpenEXR, which is a linear format (no color space transform), blend them together and then apply the display and view transform (sRGB + ACES 1.0 SDR-video) at the end.

[jrw2]

I've tried your suggestion, exported as exr from C4D, then downloaded the OpenColorIO plugin and the OpenColorIO configs, ran the plugin to create two transform LUT's and the blending now works correctly. Only the two diffuse and specular AOV's are needed. However I've run into another problem. For the color replace tool to work, the image needs to be converted into an 8 bit image, with all layers intact. But after this conversion, the colors get janky again. 

Another way is in Arnold settings to set the color manager to C4D, which has the settings Linear/sRGB, then export to exr. This way the blending also works correctly, but when converting to 8 bit, the resulting image is too bright. 

How can I get correct colors and blending with 8 bit in Photoshop, with layers intact?

[peterDTE7K]

I gave up on trying to composite anything in Photoshop. It has zero color management capabilities. Photoshop and all its tools work well if you stay in sRGB color space. Proper software for this job are either Davinci Fusion or Nuke.

[jrw2]

I've just found out the Photoshop replace color tool doesn't work well for dark colors. Add to the insanity of color depths and conversions, I've given up doing this in Photoshop. Instead, I used the take system in C4D to create a take for each color variation, by having the takes record the color changes done to the standard surface base color, and render all takes. For 43 color variations with 2 colors to change each took about 20 minutes of work, not including rendering time, so not too bad.

[lee_griggs]

Glad you found a solution 🙂