Can GIMP replace Photoshop?

Almost everyone has heard of Adobe's Photoshop, but far fewer people have actually paid for it. With prices necessarily high to combat piracy of its flagship application, Photoshop is beyond the reach of most casual users. Even professionals in small businesses may find the program's list price of £485 (ex. VAT) prohibitively high.

Fortunately for the budget-strapped, there are alternatives to Photoshop, some of which cost absolutely nothing. The most popular is the open-source project, GIMP (GNU Image Manipulation Program), which has won many fans over its several years of development.

But can you really replace Photoshop with free software? For basic operations, an advanced application like Photoshop certainly isn’t necessary — even professionals, who use the program daily, often make use of only a fraction of its capabilities. Only a small subset of Photoshop’s features is required for everyday tasks such as editing pictures for web use or retouching photos from digital cameras; much simpler applications, including free ones such as GIMP, can do the job just as well.

GIMP is a favourite among Linux fans, coming preinstalled or easily installable on many distributions. It's also available for Windows and Mac OS X. For many people, GIMP offers all the image manipulation tools they need: most of Photoshop's core functions are present, and its functionality is being expanded all the time. In this article, we examine just how far a serious (professional or semi-professional) user can get with GIMP.

Basics
If we consider a simple task such as editing a digital photograph, it's clear that Photoshop and GIMP can provide very similar working environments.

Obviously there are some differences in layout and terminology and, as you delve deeper, you may notice some bits missing from GIMP as well as usability differences. However, the navigation, layer and history palettes are all essentially the same in both applications.

What can’t GIMP do?
Although new features are being added all the time, GIMP is currently missing some major features. Some of this functionality isn't essential — it may make life easier, but with a little effort it can be lived with. Some missing features can be added via plugins and extensions, but inevitably some users will come across show-stoppers — features without which they simply can't do their jobs.

So let's start with the biggest issues, bearing in mind that the goalposts are constantly moving: if GIMP doesn’t do it already, then there’s probably someone coding away furiously to make it happen, be they part of the official development team or not. However, for now, if you absolutely need the following features, then GIMP won’t be of much use to you.

Bit depths higher than 8-bit
When using GIMP, you’re restricted to images with 8 bits per channel: for an RGB image, 8 bits per channel gives 2⁸x2⁸x2⁸ = 16,777,216 colours. Although the vast majority of digital camera images use a maximum of 16.7 million colours, advanced users often need to use high bit-depth images of 16 or more bits per channel.

Examples of such images can be RAW or TIFF images from digital cameras, as well as those produced by high-end scanners. Today, it’s popular among both hobbyists and professionals to make use of RAW images as digital SLRs keep falling in price and HDR (High Dynamic Range) photography increases in popularity.

Unfortunately, you’re not going to be able to work with any of these types of image in GIMP. But don’t despair: A fork of the GIMP project, originally known as 'Film GIMP', is designed specifically with high-bit depth processing in mind, and is used in many high-end professional environments such as movie-making. It’s now known as Cinepaint and you can download this software free of charge. Although it’s aimed primarily at retouching movies and comes with support for various esoteric industry-standard file formats, you can also use it to process high bit-depth images from professional-level cameras and scanners.

The code base for Cinepaint forked away from GIMP several years ago, and has not seen the same level of development. So if you work with both 8-bit and high bit-depth images you may find you need both packages to get all the features you need.

No CMYK

If you use Photoshop to create artwork for print, then you can forget about replacing it with GIMP for now, as GIMP supports only RGB colour. CMYK support is due to be added, but for now it's not available. If you’re sending artwork or images off to repro, they’re going to want everything in CMYK mode; and if you want to see on-screen how things will look on paper, you’ll need a CMYK preview mode. Furthermore, Pantone colour requires licensing and is therefore unlikely to be included in a free software package, so there’s no industry-standard spot colour capability.

The lack of CMYK therefore makes GIMP unsuitable for use where you’re producing professional work for print. It’s still absolutely fine for printing on your inkjet at home or at a kiosk, as these printers use RGB drivers anyway. Lab colour is also missing from GIMP, leaving you with only device-dependent RGB to work with, which brings us on to the next missing feature.

No colour management
Accurate colour reproduction is critical for imaging professionals, and Photoshop takes full advantage of the colour management support available in Windows and Mac OS X.

Full support for ICC and ColorSync profiles means that you can guarantee consistent colour from one PC to the next. This means you can create accurate — or at least repeatable — soft proofs, predicting with some degree of certainty what colours will end up in print or whatever your final delivery medium might be.

As standard, the GIMP has no support for colour management, although attempts have been made to incorporate it via plugins. The good news is that the forthcoming version 2.4 release of GIMP will incorporate native support for colour management. Current releases of CinePaint also support colour management on Linux.

Colour management is something no-one wants to have to worry about, and much work has gone into making it happen mostly behind the scenes in Windows Vista. Unfortunately, when it’s not happening at all, getting your photos to look right can result in you attempting all sorts of strange adjustments to compensate for your poor monitor, or the fact that you’ve loaded a photo from a camera set to Adobe RGB mode.