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The Generic Graphics Library (GEGL) is a programming library under development for
image processing An image or picture is a visual representation. An image can be two-dimensional, such as a drawing, painting, or photograph, or three-dimensional, such as a carving or sculpture. Images may be displayed through other media, including a pr ...
applications. It is mainly developed for
GIMP Gimp or GIMP may refer to: Clothing * Bondage suit, also called a gimp suit, a type of suit used in BDSM * Bondage mask, also called a gimp mask, often worn in conjunction with a gimp suit Embroidery and crafts * Gimp (thread), an ornamental tr ...
in order to add support for higher bit depth images, and non-destructive editing. It was partially implemented in GIMP 2.6, with more added in 2.8, and is now a central part in 2.10. Many Filters are ready, but also much work in progress. Target is full support of all important filters in roadmap in Version 3.0. It is also used by GNOME'
Photos
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gedl


Design

GEGL is modelled after a directed acyclic graph, where each ''node'' represents an image ''operation'' (called "operators" or "ops"), and each ''edge'' represents an ''image''. Operations can in general take several input images and give several output images, which corresponds to having several incoming edges (images) and several outgoing edges (images) at a given node (operation). The system uses an on-demand model, doing work only as required. This allows features such as having very quick previews while editing, and once the user has finished making changes, GEGL will repeat the same operations in full resolution for the final image in the background.


Operations

An operation (op) is a node within a GEGL graph responsible for one action; ops can be: * simple, such as "add" (taking two inputs) or "premultiply by alpha" (taking one input) * complex, such as colorspace conversions GEGL also has a notion of meta operations, where one operation can be constructed from other operations (e.g. ''unsharp mask'' is a combination of ''add'', ''multiply'', ''subtract'' and ''gaussian blur'' ops).


babl

babl, a support library for GEGL, provides a generic way to deal with color-space conversions; babl operates abstracting the fundamental color operations so that GEGL need not be aware of them. Through babl, GEGL provides an optimized and powerful (optionally with
SIMD Single instruction, multiple data (SIMD) is a type of parallel computer, parallel processing in Flynn's taxonomy. SIMD describes computers with multiple processing elements that perform the same operation on multiple data points simultaneousl ...
support) treatment of arbitrary color data; this enables dependent applications to efficiently support a wide range of color spaces (from 8-bit RGB to full floating point
CMYK The CMYK color model (also known as process color, or four color) is a subtractive color model, based on the CMY color model, used in color printing, and is also used to describe the printing process itself. The abbreviation ''CMYK'' refers ...
) with minimal extra application code.


OpenRaster

OpenRaster is an
XML Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing data. It defines a set of rules for encoding electronic document, documents in a format that is both human-readable and Machine-r ...
file format A file format is a Computer standard, standard way that information is encoded for storage in a computer file. It specifies how bits are used to encode information in a digital storage medium. File formats may be either proprietary format, pr ...
used for saving
raster graphics upright=1, The Smiley, smiley face in the top left corner is a raster image. When enlarged, individual pixels appear as squares. Enlarging further, each pixel can be analyzed, with their colors constructed through combination of the values for ...
. GEGL's lead developer Øyvind Kolås has helped specifying OpenRaster so that it is capable of saving a GEGL graph.


History

GEGL was originally conceived as a GIMP core replacement in 2000 by Rhythm & Hues software engineers, finally in 2006 the external
API An application programming interface (API) is a connection between computers or between computer programs. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how to build ...
was deemed stable enough and capable of replacing the GIMP core. On 20 December 2007, it was added to the development version of GIMP. Some of GIMP's tools have already been converted to GEGL operations; mostly tools which modify colors, brightness or contrast have been converted. Version 0.2.0 is Part of Gimp 2.8.xy and Series 0.3.xy is Part of 2.9.x and in 2.10.0 Release Candidates. 0.4.0 is first Version for Version 2.10.0 of Gimp. Actual Version 0.4.xy is also base of development Version 2.99.x for stable 3.0 series of Gimp. 0.5 (or higher like 1.0) will be the line of 3.0 stable series. As of unstable 2.9.x series, all of GIMP's core relies on GEGL, and almost half of filters have been replaced with GEGL operations. Target is 100% of canvas filters in GEGL in 2.10 and later. Historically, the GEGL mascot, a five-legged goat created by , found life as an
easter egg Easter eggs, also called Paschal eggs, are eggs that are decorated for the Christian holiday of Easter, which celebrates the resurrection of Jesus. As such, Easter eggs are commonly used during the season of Eastertide (Easter season). The ...
in GNOME desktops.


OpenCL

Some of GEGL's operations are available in OpenCL-based hardware-accelerated version. A 3rd party effort, called GEGL-OpenCL, of converting more operations to
OpenCL OpenCL (Open Computing Language) is a software framework, framework for writing programs that execute across heterogeneous computing, heterogeneous platforms consisting of central processing units (CPUs), graphics processing units (GPUs), di ...
was started by Stream HPC in 2016. The project was stagnant starting May 2017, but was revived in the summer of 2019.


References


External links

* {{Official website
GEGL Mailing List Archives
C (programming language) libraries Beta software Free computer libraries Graphics libraries