Best Linux photo editors: 6 top image suites on test

6th May 2013 | 15:00

Best Linux photo editors: 6 top image suites on test

We try out the best photo editors on Linux

There's still a lot of prejudice against Linux amongst photo enthusiasts and pros, but the time at which our favourite operating system wasn't taken seriously for image manipulation is long past. There may be no Adobe- or Apple branded software designed for Linux yet - and would we want it if there was?

But there are more than enough serious, mature packages for everything from basic library management to RAW development. It's entirely possible to run a professional studio without the aid of Windows or a Mac these days. There's such a staggering amount of choice, in fact, that whittling them down to just six for this roundup involved making some very tough decisions about what software to include and what to leave out.

Inevitably, there are some familiar faces. Gimp, although covered ad nauseam elsewhere, can't be overlooked when it comes to an allround package for post-processing shots. Likewise, you may already know more than you could ever want to about the Gnome and KDE staples Shotwell and digiKam - but they're the de facto choice for a reason. Leaving them out of this roundup would be to not consider the very best.

The real controversy, in fact, is whether or not to include Corel's AfterShot Pro – nee Bibble – in the roundup. It's the gold standard for RAW image editing on Linux, but it's also closed source and not terribly cheap either, at $59.99 for the full version. It has been updated since we last looked at it, though, so we're going to revisit it at the expense of a truly FOSS alternative.

It feels wrong, but it's the right thing to do. Disagree with our choices? Email us at www.linuxformat.com/forums.

Our selection

AfterShot Pro
Gimp
Shotwell
digiKam
Darktable
Fotoxx

How we tested

It's hard to directly compare a lot of the software here, since it's all been developed with slightly different purposes in mind. The basic tests, however, were standardised as much as possible. We challenged each application to catalogue a library of several thousand images, and looked at how it coped with developing RAW files, editing photos in JPG format and batch processing resize jobs and filters.

Not all of the apps listed can do all of those things, of course, but while there's a fair emphasis on features what really counts is speed, ease of use and the end result. If it's faster to use one app for taking care of where photos are stored and finding them and another to do the editing, that's fine by us.

Casual or pro?

Test one

Who's the software aimed at, and should it matter in terms of ease of use?

There's an array of audiences catered for in our six candidates, and intentionally so, but none of these packages is short on features. It's more about the way they're presented and interact with one another.

So, if you're looking for something simple just to manage your photos and remove a bit of red eye, then distribution stalwarts digiKam and Shotwell should be amply suited to your needs. Both focus on the essentials of a photo manager, and while they have in-built editors neither are prescriptive or force you to use them.

Shotwell, especially, is designed for simplicity of use with the same kind of bare minimalism that developer Yorba has injected into its excellent email client, Geary. Open it up and you get photos on the right, and sorting options on the left, with little else between. The image editor is almost app-like in its simplicity, though - there's a one-click Enhance button, which spruces a pic up before you publish it to the sharing site of your choice.

DigiKam is far more fleshed out, however, and full of options and features for the tinkerer. It's difficult to say who digiKam is for, though. The Library tool is exceptional, allowing you to sort by date, tag, facial recognition and even a 'fuzzy search' that tries to match general shapes to an existing image - you're invited to 'sketch' the shape you want to find in a blank box and digiKam will try to find it.

Aside from the slightly variable results from fuzzy searching and face matching, though, digiKam can prove to be a bit intimidating for the very casual user, without containing powerful enough editing tools to please the professionals.

AfterShot Pro, as the name suggests, is a proper tool for proper photographers. It has a sophisticated library manager, a reasonable image editor and arguably the best RAW development tools of any software on any platform. It's also not expensive when compared with the likes of Lightroom or Aperture, although having said that it isn't cheap enough for the faint-hearted.

Darktable is designed purely for handling RAW files, but is better suited - in our opinion - to the enthusiastic amateur photographer than the pro. It's got an incredible number of features, and can do everything that AfterShot Pro does, but it's infused with the spirit of open source and too infinitely tweakable to fit comfortably into a serious workflow. Wrestling every picture into perfection is fine if you only have two or three to fine tune - not if you need to process hundreds of shots in a day.

Gimp, meanwhile, is still overwhelming for the novice despite a recent makeover. However, lack of competition for picture editing functions, like a clone brush and layer control, means that it'll find its way into most photographers' toolboxes, whether you're just brightening party shots taken on your phone or looking to create artwork for high street advertising campaigns.

Verdict

AfterShot Pro - 5/5
Gimp - 4/5
Shotwell - 4/5
digiKam - 4/5
Darktable - 3/5
Fotoxx- 2/5

Photo management

Lots of images to look after? Which one excels at it?

Most of us start off managing our image libraries using a standard file manager and some cleverly named folders. Some of us stick with that through our entire careers. But why complicate things when you can double-click on 'Christmas 2012' and Nautilus or Dolphin et al will throw up a page full of browsable thumbnails?

With one notable exception, all of our candidates have some form of library management in their design. Gimp is a pure editor, and wisely eschews trying to do too much.

Library management is at the heart of Shotwell and digiKam, and both do the job well. DigiKam will sort your shots by any combination of folder, date and EXIF or tag you want, although the interface can be a bit cludgy once you move away from the file tree. Shotwell is a little more limited, as it sorts everything by date first - which can be problematic if you don't tag your shots with subject information.

AfterShot Pro, meanwhile, has a very sophisticated library function that allows you to sort photos according to just about any parameter. Unfortunately, it's let down by an import function that is overly complicated, and won't automatically watch folders for updates, so the in-built file browser is better.

That's probably the reason why Darktable's library management reflects the file structure on your hard drive - it's simple and lets the app get on with generating fast, browsable thumbnails.

Fotoxx, again, displays its weirdness here. It should be a library manager, but operates more like a file browser, in which there's no obvious way to go up a level. Odd.

Verdict

AfterShot Pro - 3/5
Gimp - 0/5
Shotwell - 3/5
digiKam - 4/5
Darktable - 1/5
Fotoxx- 1/5

Interface

You've got the package, now how easy is it to get around?

AfterShot Pro - 5/5

AfterShot Pro

If you've used a RAW editor in the last decade or so, the layout of AfterShot Pro will be instantly familiar to your eyes. On the left, you have the browsing controls - a file manager, a library viewer and some settings for filtering and searching for shots.

In the middle is a digital light table that shows thumbnails or zooms to individual pics for editing. Over on the right, meanwhile, are the editing tools. Laid out in a fashion not designed for efficient use of screen space, but named and ordered in an intuitive fashion such that most photos can be edited from the default tab, with advanced options for harder work cascading behind.

It's not the prettiest or most modern photo editor, but neither does it look dated or make the user work to find essential tools. Top marks.

digiKam - 3.5/5

Digikam

Few things are more than a click away. It opens up onto a library manager, and you can rearrange the view according to title, date taken, metatags, ratings and more, or switch to a fully-fledged RAW importer and photo editor.

This is also a problem, as by default there are icons running down both sides of the main frame, and lots of controls to remember. It's perfect for someone who handles a lot of images and wants to stay within digiKam for everything, but if you aren't going to use the extra controls, it's cluttered.

Plus some of the cooler features - like the spinning globe for GPS tagging photos - are slightly buggy. The date sorting panel looks great, but is less usable than Shotwell's dull folder tree. Being a native KDE app, though, it is eminently tweakable.

Shotwell - 3/5

Shotwell

Now Google's Picasa is no longer maintained for Linux, Shotwell is the next best thing to a dedicated library manager that focuses on helping you find a photo fast. By default, it sorts images by time taken using a timeline on the right that looks rudimentary, but is easier to get around than the one in digiKam.

You can also view by tag or EXIF information - although these options aren't obvious and require going through the View menu. There's a one-click photo fix button, and it uploads shots and albums directly to a vast number of photo sharing sites.

Shotwell is simple, but not yet elegant. The rounded icons used for folder and album views look slightly out of place, and the functional sorting column on the left could do with a little love.

Darktable - 3/5

Darktable

The guiding principle for Darktable seems to be to take the established design of a traditional RAW editor and simplify it. To this extent, it is a massive success. The library view is simple and straightforward, and the editing tools seem initially straightforward too. Then there's the little flourishes, the swirls that are reminiscent of a silent movie panel that decorate the black background.

But while it looks simple, Darktable is a challenge to use. Editing menus are labelled with icons rather than words, and named unintuitively. Controls are divided into Basic Group, Tone Group and Explicitly Specified by User. Some of the more commonly used controls aren't available, but have to be added from the hidden Plugins menu.

Set it up right, and Darktable is an efficient tool laid out to your way of working. But for most, the learning curve is staggeringly high.

Fotoxx - 2/5

Fotoxx

There's something a little Windows 98-ish about the interface of Fotoxx that will put most users off trying it. Not to give it a go, however, is to miss out on some of the wonderful lunacy that's gone into the design.

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

The gimp

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?

Colour management

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.

Verdict

AfterShot Pro - 5/5
Gimp - 5/5
Shotwell - 3/5
digiKam - 4/5
Darktable - 4/5
Fotoxx - 3/5

Plugins

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.

Gimp, for example, has a large and well established library of plugins, including one that makes it look like PhotoShop. Fotoxx, meanwhile, treats plugins as simply a custom menu command to launch an external editor.

Shotwell and digiKam come with most of the available plugins already installed - and many are geared up for accessing photo sharing sites without leaving their respective environments.

In Darktable nomenclature, every function and set of image sliders is a plugin. It's highly extensible, in that you could add more than the default set of functions, except that there aren't any extra ones to download - as far as we can see. If Darktable can capture a large enough audience these will surely come.

When AfterShot Pro was known as Bibble, there was an enthusiastic community of plugin developers, both free and commercial. The good news is that these have gone with the project to Corel, and the forums there are full of homemade packages for geotagging, framing and generally messing up or improving pics as you see fit.

Verdict

AfterShot Pro - 5/5
Gimp - 5/5
Shotwell - 3/5
digiKam - 4/5
Darktable - 3/5
Fotoxx - 1/5

Outputs

Outputs

Happy with your editing results? What about the file format?

There are two questions to address here. Firstly, what's the quality of the final photo like? And what can you do with it? Gimp, for example, isn't yet capable of 16-bit colour precision, which is a problem for professional photographers working in print. It also has an annoying insistence on working with its own file format, .xcf.

Almost everything in Gimp 2.8 was an improvement, apart from the decision to remove other file formats from the Save as dialogs and move them into an Export menu. There are logical reasons for this, but it gets in the way of established workflows and introduces two extra layers of dialog boxes just to output a JPG in the format it was opening from.

DigiKam, meanwhile, is the opposite when it comes to file formats and is happy to upload and download from any photo sharing site, too. Some of these online plugins are a little unreliable, and the chances of tags and metadata getting through unscathed are variable.

Shotwell has fewer online plugins, but all the main social sites are covered just fine. For a RAW converter, AfterShot Pro has a surprisingly diverse range of output options. There are no direct plugins for online sites, but you can create everything up to 16-bit TIFFs in terms of quality and output to ready-made web galleries or contact sheets. It means that for many shots, no external editor is required to get the perfect picture from camera to client fast. It's not without quirks, though - the output dialog is over-complicated and offers to add more effects, like sharpening, without a preview.

In the most recent update to AfterShot Pro the developers also addressed its previous biggest flaw: the default colour balance for pictures is not much more natural, and not quite as eye-poppingly 'contrasty' as before. So it's easier to get great quality shots first time.

And that brings us back to our major criticism of Darktable - despite the apparent simplicity of the interface, it's complex to use, which increases the chances of making a mistake. You can't save an image directly after editing it, for example - you make the changes, go back to the thumbnail view, then find Export Selected Images. It'll suit some workflows, but makes it inflexible to use.

As far as image quality goes, however, Darktable is capable of results on a par with AfterShot Pro - if you can master the controls.

Verdict

AfterShot Pro - 4/5
Gimp - 4/5
Shotwell - 4/5
digiKam - 4/5
Darktable - 3/5
Fotoxx - 3/5

Multithreading & performance

Fancy features are all well and good, but can it get the job done fast?

Camera sensors are getting bigger, more of us like to work in RAW formats and bandwidth limitations are no longer critical for reducing picture quality and size before uploading. Plus, we're shooting a lot more photos than ever before. Image files aren't getting any smaller, and our libraries are expanding rapidly. So photo editors are in a Red Queen race: they need to be more efficient than ever just to seem as good as they were.

With the exception of Fotoxx, all of our software here is multi-threaded and can take advantage of more than one processor core. digiKam and Shotwell are surprisingly fast at dealing with large libraries of photos and helping you find the shot you want. Neither are perfect, though: Shotwell feels a little buggy and slows down at seemingly random periods, while digiKam's interface is often the stumbling block. Opening up a RAW file, for example, means going through a tedious and old-fashioned import screen rather than going straight to the meat of the editing tools.

As far as our dedicated RAW editors are concerned, AfterShot Pro is incredibly fast at cataloguing and editing files, and designed to get the most out of your workflow. It's still a little sluggish at dealing with picture layers, though, so you'll likely want to fall back on Gimp for fine grain editing.

Darktable, meanwhile, is fleet-footed in thumbnail mode, but once you start layering edits onto an image it quickly takes its foot off the metaphorical gas and begins to get frustratingly slow. Even zooming in to a shot takes too long (and there's no slider to show you how far you've zoomed in either).

The triumph of the latest release of Gimp, meanwhile, is its support for multi-threaded processors and - if you're prepared to tinker - OpenCL for GPU acceleration, too. The upshot is that nothing on Gimp 2.8 feels like a chore, so long as you know what you're doing.

Verdict

AfterShot Pro - 5/5
Gimp - 5/5
Shotwell - 3/5
digiKam - 4/5
Darktable - 3/5
Fotoxx - 3/5

The verdict

AfterShot Pro

One thing we haven't covered is picture quality. Gimp remains the only really serious tool for all-round work; Darktable gives AfterShot a run for its money, but struggles without a hefty CPU behind it.

Ultimately, there is no one tool that does it all, and where applications try to take photos all the way from hard drive to output in one go they inevitably fall down somewhere.

AfterShot Pro's library management is a bit too intense for daily use if you're just browsing through old snapshots, while digiKam's RAW developer would drive you insane. The best set-up for RAW shooters would be Shotwell for image management and AfterShot Pro or Darktable for developing pictures.

For the casual snapper, digiKam works wonderfully on both KDE and Gnome, although you'll probably end up wanting to cover two thirds of its icons with sticky tape. Where Shotwell's editing tools are too basic for most, digiKam can be quite overwhelming.

Which brings us onto Gimp. That it should, after all these years, remain the only real choice for lightweight or heavy lift editing activities seems like a missed opportunity, but the only piece of software that can survive without its touch-up skills is AfterShot Pro - and even there it's easier to fall back on Gimp for fine tuning.

It's not often in Linux that there's only one way of doing things, but we feel everyone who edits photos should have Gimp installed. The lack of 16-bit colour precision means it has limitations for professionals, but it's more than adequate for most needs.

So what of AfterShot Pro? It pains us to admit it, but the fact that this is the product of a large company with a lot of resources shows. Only Gimp comes close to its level of sensible design choices and bug-free execution, and even then it tends to stray off into a slightly bonkers world of its own. We salute Corel for continuing to support Linux with such a fine piece of software.

Fotoxx is wonderfully quirky, and has an insane feature set for an application that appears so simplistic on first boot, but it's not mature enough yet to compete with the established names.

Final scores

AfterShot Pro - 5/5
Gimp - 4/5
Shotwell - 3/5
digiKam - 4/5
Darktable - 3/5
Fotoxx - 2/5

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