Hello! RawTherapee runs reasonably well on my Pi3, which says alot about the programming efficiencies used. The UI is responsive and effective at screen sizes from 640 x 480 and up. The Pi’s limited RAM forbids complex operations. Denoise, contrast by levels, and other heavy lifting overwhelm its RAM and default swap.
Processing an 8MB RAW file with basic corrections takes about 20 seconds. I will try with an expanded swap file - It will be slower, but should finish complex operations.
This is cool! I’ve Ubuntu MATE on my pi 3, and it runs pretty well.
Nice. Since a (short) while darktable’s development version can be used on the pi, too. Here I am using it on a pi3 with the official touchscreen. Not ideal, but it kind of works. Part of the problems are due to bugs in Debian, part are darktable not being touch friendly. 
Doesn’t the Pi use an ARM processor rather than x86? Does this mean that RawTherapee and Darktable can be ported to run on phones and tablets which should have more horsepower?
Yes, I am going to try and install them when I get my bq Ubuntu tablet.
Raja, the Pi does use an ARM processor - A quad-core 1GHz ARM unit. With a
small screen (And a small photo to calculate changes on, the Pi is
reasonably responsive. But its 1GB RAM is a limit that will not easily
change, and any program will crash when it is not given the RAM and Swap it
needs. For installing on the Pi, I typed “Sudo apt-get install
rawtherapee,” and it worked. I have not rooted my Android phone, but it
would probably have the lifting power to run RawTherapee with all filters.
I have still not configured a USB drive as swap - It’s been a busy week.
Kris Tesh
Kristopher.Tesh@gmail.com
Interesting. I’m impressed that the Pi3 can handle RawTherapee at all.
Raja - Well, I have hit another block on this. I activated an extra 2GB of
swap, and still crash out on the ‘complex’ tools. I suspect that the 32
Byte OS I am using is tripping over itself on heavy lifting, or else I need
to look into the swappiness settings.
So - It is pretty capable in browsing RAW files, and in previewing edits.
That says a lot about the programming work to speed up RawTherapee, and on
the steps for tiny computer power.
I have also started to wonder about moving the queue of photo+edits to
another computer for the heavy lifting. I don’t have good tools to
investigate this option, but I’ll start playing with it, also.
Kris Tesh
Kristopher.Tesh@gmail.com