How can I blackout the background of a photograph in RT?


Hi all, first post, hope is in the right place :slight_smile:

Is it possible to completely blackout the background of a photo and how can I achieve that?


Maybe. Could you show us the photo in question?


Yes if you tell me how!


Easiest is to make a small jpg and drag it into your post. That way we can have an idea of what you are dealing with.


I would say: “No”, RT is not a painting or drawing program.


I say maybe because if the subject is well lit enough, and the background is significantly darker, a simple move of the black point could do it.

For example, I took this rose photo in broad daylight at one of our local municipal rose gardens, and processed entirely in RT.


Thanks for your help, wow, nice photo and interesting technique!

I tried to capture the face just slightly blending with the dark background so I took the photo in total darkness on a black sweatshirt while hand holding a candle in order to achieve the desired effect:



Basically it’s an image of Mother Mary painted on a pebble.

Maxing the blacks didn’t work because the image was pretty dark already so I thought of applying an ND filter on the left side but the candle was still visible. So then I saved the image and applied the ND filter two more times and BOOM, it worked :smile:



I would like to know if there is a different way to do that because applying multiple ND filters and saving is not very convenient :unamused:

(dngimage) #8

You may want to try RawTherapee’s Local Lab version. You will find it here:

It can be done with the image you posted, but it doesn’t work well with some images. The current Local Lab version is broken so you may want to wait for Jacques to post an update when he gets back from a well deserved vacation.


Thank you, it seems ideal. Can you please let me know when the update is done :grin: ?

(dngimage) #10


Keep checking here for updates:


I would use the grad and vignette in the exposure section, and then a negative vignette correction in the transform section.
Local lab also makes sense, as that reminds me of burning the center with the hands in photo paper exposure in an actual darkroom.


If the grad and vignettes still aren’t enough, I might also add some highlight reduction by one or more of the various means of accomplishing that, for instance on the tone curve in exposure, where you can isolate the bright part of the candle flame from the dimmer pebble. I’m a few days away from my computer, otherwise I’d show some screenshot examples.


Thank you HIRAM, the vignette filter is a great idea for the occasion indeed :relaxed:

I also tried the simple highlight reduction but unfortunately it didn’t work for me.