Deep Images

CinePaint is the descendant of the Rhythm and Hues fork of The GIMP, and it expands on the broad file format compatibility of that branch. In the intervening years, it has grown into a dependable scratch-and-dust removal program for motion picture films and is now pushing toward becoming a proper compositing system. It is currently under heavy development in its Glasgow branch, while the original branch is more or less stable and being updated only for bug fixes and small feature additions. Aside from the basic GIMP feature set, CinePaint sports a proper color management system—the very thing whose absence renders GIMP inappropriate for professional and near-professional work. There is also a flipbook player for tracking changes across animations, write-out to Cineon and OpenEXR and an excellent plugin for assembling High Dynamic Range images from regular snapshots (a process called bracketing). It is currently the only open-source GUI program for Linux that supports bracketing.

The interface is familiar—any GIMP user will feel right at home—and its other features make it an indispensable part of any photographer's graphics toolbox (Figure 1).

Figure 1. CinePaint has a UI similar to GIMP.

However, CinePaint's intended market is movie retouching, so its feature set for photographers is fairly limited beyond the basics and some of the impressive new features. Its early forking from GIMP and its radically different internals mean that GIMP plugins do not port easily to CinePaint, so casual users will find themselves frustrated by what feels like a functionality hit. Further, it is difficult to compile and fairly crash-prone on some distros (this is part of the reason for Glasgow's move to FLTK, but that branch isn't yet usable). Even with these inconveniences, CinePaint is still a must-have tool, and as the project moves forward, it will hopefully become ever-more useful and stable.

Krita is the KOffice paint utility, and it's enough to make people rethink their dislike of KOffice (Figure 2). Even at first glance, it looks like a whole different animal than GIMP. Rather than floating windows, it starts in a single-pane, integrated view. Thankfully, there is salvation in the fact that Krita's design is modular: every panel and tool is dockable, making the user interface as configurable as you please.

Figure 2. The Krita interface is designed for graphics professionals.

The differences don't end there—Krita's entire approach sets it apart. GIMP originally was designed to give UNIX a way to deal with Web images, and it fulfilled this mission admirably for a long time. Krita, on the other hand, was designed with a different target in mind—it is aimed directly at graphics professionals.

Built from the ground up on LCMS, Krita's 32-bit color management system is flanked by well-built, sophisticated tools for accessing it. It works in more than a dozen different colorspaces and converts between them cleanly, making it suitable for a broad range of professional graphics demands (CMYK and RGB are only the beginning). For print work, Krita has its bases well covered, something that GIMP hasn't yet mastered.

Though not managed by a graphics professional, Krita's design shows a deep familiarity with graphics processing engineering. It starts with much more sophisticated drawing and selection tools than have been available in Linux before—from guided line drawing that aids precision when working without a Wacom tablet to a magnet selector for modifying existing selections on the fly. The number of drawing tools is rivaled only by Photoshop, and there are a few nifty enhancements in this area where Krita outdoes the venerated veteran from Adobe. It's not above pinching some of Photoshop's better innovations, either.

Adjustment layers are finally here, as are layer grouping and layered effects stacks—a distinct advantage over the GIMP/CinePaint paradigm. No longer must one apply a single adjustment, make sure it's right, and then move on. With the power of adjustment layers and filter stacks, the changes are applied to the image only on export, which makes mid-stream tinkering far more efficient.

Krita also has a few tricks of its own, such as the Filter Brush, where one can paint a filter's effect directly onto the image in specific places, rather than being forced to use the powerful but tedious process of masking different layers in great detail.

The guesswork of filter selection is also a thing of the past. Rather than bringing up standalone filter dialogs and tweaking them while watching the preview as one does in GIMP, users may use the Filter Gallery, which lists all installed filters, provides full access to their parameter UIs and includes thumbnail previews of their default settings side by side with one another—not the little window covering a piece of the image such as one gets in many GIMP previews, mind you, but a full thumbnail preview (Figure 3).

This work-flow streamlining is great and doubtless will make its way back into other applications as Krita gains notice.

Figure 3. Krita supports full thumbnail previews.

Krita excels in scripting support as well; the Python and Ruby engines behave more like Adobe's Action scripts than like GIMP's and are pleasantly non-crash prone.

As a cherry on top of this already tempting sundae, Krita has a number of color profiles to chose from—a must in today's world of multifaceted graphics acquisition. Different cameras, scanners and graphics programs use different color profiles for different reasons, as do different printers and destination formats. These color profiles govern how the picture is interpreted and parsed by programs and devices, and if you want your colors reproduced accurately across today's myriad devices, your graphics package has to be able to speak several languages. NTSC, PAL and SEACAM video formats all have peculiar color profiles, professional print shops use CMYK, different digital cameras use Adobe RGB or sRGB, Apple has its own color profile, as does SMPTE. All of these, and more, are supported in Krita by default (Figure 4).

Figure 4. Krita supports several color profiles.

Alas, not everything is hearts and flowers. Krita's text tool is primitive—like GIMP before its recent improvements, it rasterizes text as soon as it's added so it can't be edited later. Like CinePaint, it can't use GIMP filters, so new plugins have to be written to its architecture. Because of this, the ability to duplicate some of the basic GIMP filters, such as procedural plasma generation, simply don't exist yet. Still, what filters are there do a bang-up job and often eclipse their GIMP counterparts.

Krita also is still in the refinement stage, and its code is not well optimized. It has a high system overhead—it looks pretty, but it drags on the resources of even a well-equipped system. The adjustment layers don't require multiple copies of the same image in order to stack filters, so the load is lighter. Even so, the interface can lag, a lot. Unlike both GIMP and CinePaint, Krita doesn't yet have any animation capabilities, to say nothing of a flipbook. Finally, it doesn't yet support LDR bracketing to HDR—a considerable drawback (though this feature is on the to-do list for future releases).

Still, all told, Krita is an excellent package. It is very capable as is, and it shows a lot of potential.