Color balance rgb - Colouring midtones in the 4-ways tab

I’ve been using the new color balance rgb module recently and I think it’s fantastic. I really appreciate the fine level of control it offers. However, I’m a little confused over the handling of midtones.

The 4-ways tab is where colour is added, changed or neutralized, but the sliders are different to the master tab in that they are not separated by shadows, midtones and highlights. The power sliders seem to be more focused on the midtones, but there’s no masking for these ones and they still affect the entire luminance range except the extreme black and white level as far as I can tell. With the shadows and highlights, you can control where the effect is applied and the rolloff by using the masks tab.

But, as per the manual, global power is not masked, so I’m wondering if it’s possible to narrow/expand the midtone range without using parametric masks.

I find the masks tab incredibly powerful for shadows and highlights, but there doesn’t seem to be as much control for midtones. Is there something I’m missing or is there a good reason for this?

Midtones are the adjustment variable in-between highlights and shadows, for the master tab. The 4-ways tab does not use them at all, since the power is already doing just that (more or less). Dealing with midtones separately may lead to non-smooth behaviours, so in the current algo, midtones are handled as an average of the highlights and shadows settings. I’m not sure what benefit it would yield to have a separate hue control over midtones anyway.

Thanks for the explanation. I’ll tell you my use case. Maybe I’m using color balance rgb when I shouldn’t be.

I’m developing some scanned negatives and using the original prints for reference. Often I get the overall white balance correct but there’s some tweaking needed in either the shadows, highlights or midtones. Highlights and shadows are easily dealt with in color balance rgb. But sometimes there’s a colour cast in the midtones, yet I don’t want to affect the highlights and shadows.

For example, clouds in the sky and the surrounding area might need tweaking, but I don’t want all the sky’s colour or all the land to be changed. Should I be using a different module in this case? I’m not really trying to target a specific colour, so I don’t find that a module like color zones is any better really. But maybe color balance rgb isn’t really suited to this…?

Create an instance of the color calibration module. Make a midtone parametric mask. Save it as a preset then add it when you need it …just use the color picker to grab the cast from an area you want and then you can tweak it with the hue and chroma slider. If they don’t come up select custom from the drop down and it will convert the control sliders to hue and chroma…you can fine tune that…in case it is not obvious less chroma will pull back on the cast removal and and more will be a stronger removal then calculated by the picker ROI…

Thanks Todd. Yes, I’ve already come up with various ways to do what I want, like your example, but I feel there should be a way of working on midtones without resorting to parametric masks. Maybe not, but I was thinking color balance rgb would do this as the highlights/shadows/midtones separation does exist on the master tab.

Ya Just not the 4 way I guess from what AP said recently … In Boris’s last video he isolates the midtones to do his Kodachrome style…3 instances in all…

And that midtones cast is not consistent with either shadows or highlights casts ? That would be unusual.

Typical scenes can be split in 2 : objects lit 100% by the main light (direct), objects lit 100% by the bounce light (reflected), and then you have all the other objects lit by a weighted mix of both. If your picture does not abide by this definition, your problem is probably something like a colored spotlight somewhere, in which case, it’s a local issue, not an intensity issue.

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Perhaps it’s not really a colour cast and my terminology is wrong. But I need to alter the colour in the midtones. Here’s an example:

The hazy clouds in the centre of the image are actually smoke from wildfire. They should look like the snapshot on the left. The snapshot on the right is after I had performed white balancing and some tweaks in color balance rgb. The sky (highlights) and foreground (mainly shadows) are the correct colour. The smoke and hills in the midground are not. They all occupy that range from midtone to low highlights. If I add red/orange with the highlights gain in color balance rgb, the blue sky will turn a purplish colour that I don’t want. Tweaking the masks helps but the sky is always affected. I really just want to add the colour to the midtones and then use masks to control the rolloff and gradient to the shadows and highlights.

What would you recommend in this situation? I got the snapshot on the left using color lookup table and working on midtone greys, but I’m always hesitant to use this module in a scene-referred workflow and I feel it’s a bit of a “hacky” way of solving the issue.

Mask and rotate the hue to adjust from what you are doing?? Color LUT should be fine …you can always put it after filmic to see how that works?? To be honest I don’t recall its default position… At some point you also just have to use your eyes and the tools that get you to where you want…