Keeping monochromatic photo files in Rawtherapee

I recently took some black and white (B&W) photos with my camera which I want to edit on Rawtherapee. However, every single time I open the file, it changes the colors and not maintain the monochromatic photo. I’ve tried to search for info in RawPedia but it was useless.

Could anyone tell how to prevent the software to change the colors?

These are the specifics of my gear and the software, if it is useful:

*Rawtherapee version 5.8-1
*OS Ubuntu 20.04.1
*Camera: Canon EOS Rebel T5i

Thanks in advance

Please correct me if I’m wrong, but your camera is not a dedicated monochromatic camera, unless you modified the sensor yourself. The raw files therefore still contain the color information that your in-camera processor used to prepare a b/w jpeg.
Since RT is a raw processor, it shows you the colors.

Enabling the black and white module should solve some of your problems.

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Correct me if I am wrong. When you change your camera to B/W the EV will switch to monochrome and the generated JPG will be monochrome - the RAW file still have all the color information.

That function is useful when working with filters, like i.e. when you put a 720nm IR filter in front of the lens.

That’s right, my camera can take both color and monochromatic photos, not only the latter. So, if I understand well, do you say I must make the photos monochromatic in RT again? Isn’t there a more direct method? :frowning:

Well, as I said, it can make color and grayscale JPEGs. But since you choose to process the CR2 files, which are raw files, a raw processor like RawTherapee will always show the available color.

You can apply a default style to your raw images from the Preferences:

Or apply these styles manually per image:

If you make your own processing profile, you can apply that as well. And if you want to go fancy, you can apply any profile dynamically based on the metadata of your images.

OMG, with the “Pop 4 B&W” the picture still needs edition but it is such a very good starting point. Thanks a lot.

That sounds a tonne more interesting; gonna check it later. Thanks again :smiley:

Just a little explanation of the underlying reason why this happens:

The data coming from the sensor is always color for a camera that is color-capable unless you physically modify the camera (CFA removal is extremely invasive and usually has negative side effects). When the camera is in B&W mode, it’s performing a color->grayscale conversion internally - so to do the same in your raw processor, you need to tell it to do a similar transformation.

(There might be some exotic camera out there that has switchable filters - and in fact this is common for astrophotography to switch filters in/out with a monochrome sensor, but 99.9%+ of typical off-the-shelf cameras have color filter arrays on the sensor itself.)

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