How to apply Photo Filter LUTs to Black & White images?

[Manusz]

When I worked in the analog era with Black and White film I sometimes used colored filters, e.g. a red filter to darken the blue of the sky.

The Photomator distribution comes with a number of Photo Filter LUTs installed which (judging by their name) seem to correspond to the filters of the analog era (see screenshot).

Now, when I convert a color image to Black & White (using the Black & White toggle switch and sliders) and then apply one of these Photo Filter LUTs the entire B&W image turns to the color of the filter.

Apparently the LUT is applied after the B&W conversion in the processing pipeline.
Although the effect may be interesting from an artistic point of view it is not what I would expect.

The only way I have found to "simulate" analog filters is to use the Selective Color sliders, but doesn't that defeat the purpose of the Photo Filter LUTs?

So my question is: how can I apply a LUT filter before the image is converted to B&W?

[Martin Chalifoux]

I would think the R, G and B sliders of the "Black and White" tool do what you are looking for but I don't really know the technique you try to emulate. However there is a way to do what you want and that is to use Adjustments masks. So instead of applying the LUT and B&W to the Image Layer, add two adjustments masks using the + button. In one Adjustment layer apply the LUT and the other apply the B&W. You can reorder these masks layers to your liking and as you do that it changes the order in which they are processes. So you can make it so the LUT is applied first, and then the B&W after that.

[Manusz]

Thank you, that technique works!
For what it is worth, I want to adjust the RGB sliders in the B&W tool to simulate the film characteristics I am after.
When that gives the rendering I like the next thing is to apply one of the colored LUT filters.
Working with separate layers for conversion and filtering does exactly that, thanks again!