[ Thanks to darkduck for this link.
]
“GIMP – The GNU Image Manipulation Program: GIMP is certainly
the most popular program for editing photos on Linux. It offers
almost all the same features as Photoshop and is very user
friendly. Making the transition from Photoshop to GIMP is a very
easy process. GIMP provides all the standard photo editing options
such as cropping, color enhancements, exposure and contrast
corrections.“GIMPShop: GIMPShop is essentially the same as GIMP but it has
been modified to be more like Photoshop. If you really do not want
to learn something new then GIMPShop is for you. The menu structure
has been changed so that the tools are in the same places as in
Photoshop. If you are unsure about trying GIMP then try GIMPShop
first.“Darktable: Darktable describes itself as a photography workflow
application: a virtual lighttable and darkroom for photographers.
It processes RAW files and allows you to edit and export images. It
is fully non-destructive, which means that they RAW files will not
be altered in the processing, instead it just allows the edits to
be held in cache before being exported into a new image format such
as jpeg.”