Comparison and compatibility with Adobe Photoshop

GIMP is sometimes preferred as a replacement for the proprietary Adobe Photoshop software. Thus, comparisons between the two are often a topic of spirited debate. There are significant differences between the two packages. For example, Photoshop is not compatible with GIMP plugins or scripts. GIMP features offer no or (with the PSPI plug-in) very weak support for plugins designed for Photoshop, such as 8BF filters.

Photoshop does not support GIMP's native XCF file format, but GIMP can read and write most Photoshop native PSD format files.

Like Photoshop, GIMP features support for 8-bit per-channel images. Its Intelligent Scissors are similar to Photoshop's Magnetic Lasso tool, and many basic tools and filters have identical functionality in both.

GIMP and Photoshop differ in their color management features in ways that matter to some users. Photoshop has support for 16-bit, 32-bit, and floating point images, support for the Pantone color matching system, or spot color and support for color models other than RGB(A) and greyscale, such as CMYK and CIE XYZ. GIMP, like other open source applications, does not support Pantone numbers for spot colors because of legal issues; it has basic CMYK support.^[43] Photoshop features extensive gamma correction support.

In addition, Photoshop contains several productivity features and tools not supported by GIMP, such as native support for Adjustment layers (layers which act like filters), layer styles and text blending options like drop shadow and glow,^[44] undo history "snapshots" that persist between sessions, the history brush tool, folders in the layer window, a free transform tool to rotate, scale and move in one tool and multiple styles fot text. GIMP also requires basic programming knowledge to build an automation upon it, usually Script-Fu (scheme) or Python-Fu, while Photoshop can record the user's actions and repeat them with a "Play" button. However, Photoshop's automation is not as powerful as GIMP's.

GIMP's open development model means that it is much more readily available and at zero cost, on more operating systems, plugin development is not limited by developers and as such has no need to compete with Photoshop; by comparison, access to Adobe Photoshop's SDK requires authorization and the commercially produced software is in competition with Corel Paint Shop Pro as well as the other Open Source, GNU or otherwise freely available manipulation applications.