How do you do basic dark frame subtraction in PhotoLab?

Hi. I can’t find how to do it anywhere.

That’s because you can’t. PhotoLab is not a pixel editor.

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Hm. Then I’m confused by what I’ve experienced of it so far. PhotoLab performs no pixel editing operations? What exactly is PhotoLab, then?

Like Lightroom, On1, Adobe Camera Raw, and Capture One; Photolab is a non-destructive parametric editor. Programs like Photoshop and Affinity Photo are pixel editors. Parametric editors are primarily designed for raw peocessing although they can be used to edit other file types.

Unlike a pixel editor, this means the original image file is never modified. Edits are displayed as an overlay and are only permanently burned into output image versions during export.

While current parametric editors have some features that in the past were generally only available in pixel editors, the number of features available in pixel editors is significantly greater.



Ah. What then is the relationship of pixel editing to dark frame subtraction? Like other edits, it is an edit which does not have to be performed destructively, and is ideally suited for raw data. I’m not understanding where pixel editing comes in, in so far as performing this in PhotoLab.

Is it that while PhotoLab provides many image editing features, dark frame subtraction isn’t one of them, not because it isn’t an pixel editor, but rather because dark frame subtraction simply isn’t offered?

Dark frame subtraction would require that two files be entered into the editor, the actual image of interest and the dark frame, in a layered configuration to do the subtraction. Photolab does not currently support layers. I personally would love to see layers/masking added to the PL toolbox, either integrated or as a separate module ala Filmpack and Viewpoint and sold separately.


Any program that edits images is a pixel based editor. Images, as on a pc, consist of a fixed size in elements the can be addressed individual. A parametric editor differs from other editors that the result, the edited image, is not saved as an image but as a list of parameters belonging to a certain function.
The question is more: how far has pl as a raw converter change to an image editor.


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Gotcha. Thanks for the responses. That’s understandable, but unfortunate. Before I make a feature request, can anyone think of a way to perform dark frame subtraction elsewhere first, without disabling my access to Deepprime denoising?

Best way I can think of is to open the file in PhotoLab, apply the denoising and optical corrections, then export as DNG with those options. Then do what you want with the resulting file.

Thanks, but first is important for me here because I have learned that most processing, including denoising, goes better for me when dark frame subtraction is performed beforehand. Though I’m betting, like us, no one will be able to think of an existing solution…

Perhaps you could apply DeepPRIME to your image of interest, then separately apply DeepPRIME to your darkframe image and finally do dark frame subtraction with the two separate images in a pixel editor like Photoshop. I have not idea if this would actually work properly, though.

I had tested this already, and unfortunately, it failed in more ways than one, but not unexpected. So I’m just really trying to avoid the reduction in quality that comes with applying the process to non-raw, preprocessed data.

I presume you’re wanting to cater for “glitches” resulting from long exposures … Right ?

In which case, (tho not actually the solution you’re asking about); you’ll probably find that your camera will do this for you - via an option called something like: “Long Exposure NR” (Sony), Or “Noise Reduct” (Olympus).

John M

only to collect some ideas this is what Raw Therapee says about DF and implemented it
Dark-Frame - RawPedia (


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Actually I’ve found that at any exposure length, dark frame subtraction can provide a cleaner starting point for post processing, depending on the sensor your camera is using. Unfortunately, most in-camera options only allow you to engage the option with exposures longer than a second or so. Plus, if you ever forget to turn it on, (or forget to capture a dark frame at the time of the photo if doing subtraction manually in post,) having the option to attempt an approximation after the fact can still be helpful. I really wish the in-camera options would just call it dark frame subtraction and let you engage it whenever you wanted, but oh well.

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