How to make RawTherapee fastererer?

Currently I’m in the process of converting myself to RT, as a substitute for LR. Tried Darktable but loathed its non-intuitive UI and lack of 2nd monitor support.

Luckily RT is not only the best alternative I’ve found to LR but also so much more advanced than LR itself. It seems perfect for my usage.

The only thing that I struggle with is the speed. In LR when viewing images in “E” mode the rendering is noticeably faster than in “dev” module.

However, there’s no such thing in RT. I use inspect tool for almost instant previewing of thumbnail images and it’s absolutely great, but the problem is the constant 100% zoom so I cannot view images in their entirety.

As the title says, I’d like to make RT as fast as it gets. Is there OpenCL support anywhere?

Currently I have my 2nd monitor half full with thumbnails and the other half is the Inspector.

Anything to add/remove?

Thank you!

There’s no OpenCL support yet in RT, I’m afraid.
If you really need to get a fast preview of images at screen size, you can try ART, which is a fork of RT, and has more advanced Inspect functions currently.

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It’s been mentioned before: CUDA SUPPORT needed, please insert in TODO. There has been some work on OpenCL support, see OpenCl · Issue #1678 · Beep6581/RawTherapee · GitHub, but things aren’t progressing steadily.

In contrast, @heckflosse keeps pumping out optimizations for CPU at fairly regular intervals. So you’re already getting the most out of RT without using the GPU.


I think you can preview in fit to view/screen size in the editor, at the bottom you have the left and right arrows to go to the next or previous photo. You can hide the panels and the thumbnails and you can make demosaicing faster if you switch to profile neutral in preferences - image processing - default processing profile.

Did I understand your question correctly?

Thanks, but I meant about previewing images before actually showing them on the main screen.

Currently we have Inspect for that. But alas, it only shows at 100% and only part of the image.

iirc darktable can now have a preview window on the 2nd screen

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Well, the thing is, relying on GPU is/was awkward in PS/LR too. It took them awhile to tweak it properly with a lot of crashes inbetween. So I imagine, if Adobe with XYZ amount of people working on it needed time, RT team would need x10 more. So I agree with @heck about optimizing for CPU as a bigger priority than GPU.

iirc darktable can now have a preview window on the 2nd screen

Yeah but it’s as useless as it gets, at least for me, as the filmstrip remains on the 1st monitor. I need wall of thumbnails shown on the 2nd monitor, like both LR and RawTherapee have. But I would also like fast previewing of thumbnails. Inspect is doing its job nicely, if only we had an option to show the whole image on the screen, rather than 100% zoom only.

There is a pr for this


I would say stop comparing with LR. It has different priorities and underlying code. Previews are fast because Adobe caches like there is no tomorrow. However, after the cache stores, or your hard disk, is full, then everything comes to a screeching halt. Therefore I prefer the way that RT and dt are handling things.

My current setup looks like this:

Main monitor is 1920x1200, right one is 1920x1080

@maboleth If you want to speed up your culling process on Linux, take a look at geeqie, which IMHO is perfect for the job. z, x, Delete or Ctrl+c are the most useful keys. :smile: After that you proceed with the leftovers in RT.

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Hey thanks, looks nice! Is there a dark mode for geeqie? :slight_smile:

Using the global Adwaita dark theme also turns Geeqie dark. Using GTK_THEME=Adwaita:dark geeqie on the command line doesn’t work for me on Debian testing but might work with your installation…

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As someone mentioned earlier, you might want to take a look at ART, a fork of RT. The Inspect tab has been extended with new features, including viewing the image as “fit to window”. It also has some local adjustment features and is generally more streamlined. As a previous LR user, it is the best substitute I’ve found, and I’ve tried just about everything!

Thanks! I will take a look at Art. I’m generally type of user/person that likes to stick to vanilla/original versions and rarely use fork software… Still if it gets the job done, why not.

My current workaround is to open gThumb and delete the junk out, leaving only keepers. Then in RT I rate best of the bunch, occasionally firing gThumb for a quick preview.

The ART program also does not support ocl/cuda hardware acceleration. But I agree. I like ART better.