It's a library management tool that hides its core function. You get a grey screen that does, apparently, nothing. Only if you're very observant will you tap the tiny letter G in a corner that fires up a file manager with a folder and thumbnail structure that works, so long as you never need to go up a level.
There's a row of buttons for file functions and navigation. It's only when you start going through the file menu options that the full range of capabilities is revealed. In any other software this wilful obfuscation and confusion of the user would be a sin. But there's something joyously quirky about Fotoxx, and it's hard not to be charmed.
Gimp - 4/5
Ah, what hasn't been written about Gimp that we can add here? Most of the improvements in the 2.8 version are in the editing engine and the GEGL framework for plugins that will lead to hardware acceleration and floating point colour control.
The basic interface is as hardcore as ever, feeling as if it's designed to intimidate newcomers into submission. There are some grudging compromises for those who've complained about ease of use. The single window option which locks dockable toolbars into place is a good start, and you can turn off dialogs that you don't need. But Gimp is a place you can do anything from simple exposure adjustments to masking and cutting out sections of an image to paste elsewhere.
Our only real gripe about the interface is that it still seems to roll a D3 every time it boots up before deciding what docks it will have open. Will there be layers and histograms? Who knows?
The most important aspect of photo editing is now commonplace
All of these applications except Fotoxx can handle full colour management. That may not sound important, but is a huge leap forward for Linux photo editors. It means they can use a custom gamut, as laid down according to ICC standards, to alter the way they display colours according to the monitor's unique characteristics, the tested colour space of the camera and that of the image - which will usually be one of the standard RGB profiles, such as sRGB or Adobe RGB.
This is vital for professional image editing, as it means the colours you see on screen are an accurate representation of what will be printed. The real credit goes to the Gnome developers for including simple colour calibration controls based on Argylla as a default control panel setting. It's easier to fully calibrate a monitor using a device like a ColorVision Spyder 2 in Gnome now than it is in Windows.
The same applies to Canonical's Unity environment, which uses the same tool. KDE is catching up - Oryanos and KCM are almost on a par with Gnome's default tools, but require a manual build and install, while XFCE's only real option is the CLI-based xcalib tool. Without setting these up correctly, there's no point having a colour managed editor, as your monitor won't be correctly calibrated.
Photographers who don't want Gnome or Unity do have one other choice, though - Kubuntu includes colour calibration by default, based on the same packages as Unity.
AfterShot Pro - 5/5
Gimp - 5/5
Shotwell - 3/5
digiKam - 4/5
Darktable - 4/5
Fotoxx - 3/5
So you can edit pictures, what else can you do?
There's no such thing as the perfect photo editor, and one thing that separates professional tools from the amateur stuff is support for extensions that add extra functionality, or act as a macro to achieve particular image effects. Plugins that increase contrast and bleach out colours have been around for PhotoShop for a lot longer than Instagram has been in existence.