Here's a problem I've been having:
I came accross an interesting MSG, and wanted to modify it by adding Gradient and lighting.
Essentially I wanted the final output to have the same color as I got at the ForceColorMap DialMod step, but with an embossed look.
I added the two extra steps ( Gradient and Lighting, each with RGB channels )
What I wound up with was an b/w embossed output without the color.
I can't figure out what I've gotten wrong. Any help would be appreciated.
fyi. I tried to attach the MSG, but kept getting a "Sorry that upload didnt work" message
Replies
I wanted to point out that it might be simpler for you to just build a PASeq that runs the original MSG preset and then runs the Gradient Lighting image operation effect to get to where you want to go. Or you could use a second MSG preset instead of gradient lighting ip op that does the gradient lighting part you are interested in as the second action step in the PASeq.
If you want to put it all in a single MSG effect, then you probably want to use the output of the Gradient processor as the Modulate In input to the Lighting processor. You are using it as the In input instead. And repeat those IO editing changes for all 3 of the different color channel passes.
If you search for the Gradient Lighting1 MSG factor preset, you can see how to set it up. Note that MSG preset first converts the RGB image to YIQ color space, then runs a single instance of the Gradient and Lighting processors on the Y (luminance) color channel, then converts back from YIQ to RGB for the output. This is a better approach that running the gradient on all 3 RG color channels, since that will probably mess with the color balance.
Thanks!
I'll follow up on your suggestions and let you know how it turns out.
I thought about using a PASeq too, but I need to understand how MSGs work, so I persevere😁
I've looked at a bunch of other PASeqs, and noticed some of them converting RGB to YIQ and then back to RGB after performing some operation, but never understood why.
Now I understand! Awesome!
a day without learning something new is a day without sunshine. LOL
Processing the 3 RGB color channels independently can sometimes lead to color shifts or distortion, depending on what you are doing. For some visual effects, it makes more sense to just process the luminance channel. So you convert from RGB to the luminance - chrominance color space, do the operation just on the luminance channel, then convert back to RGB.
Besides YIQ, MSG processors lets you work with LHS, VHS, LAB, and LUV color spaces. All of these have a luminance like channel that encodes the grayscale appearance of the image. Running an effect in the luminance channel of these color spaces will all look somewhat different, so depending on what you are doing, you could try the operation in different color spaces and see if the appearance suits you (or not).
The Studio Artist philosophy is that anything that looks visually different is fair game as an option for visual effect designers, which is why we offer the different choices (as opposed to picking some supposedly optimal color space for luminance-chrominance calculations.