OpenRaster - AbsoluteAstronomy.com

OpenRaster is a file format

File format

A file format is a particular way that information is encoded for storage in a computer file.Since a disk drive, or indeed any computer storage, can store only bits, the computer must have some way of converting information to 0s and 1s and vice-versa. There are different kinds of formats for...

proposed for the common exchange of layered

Layers (digital image editing)

Layers are used in digital image editing to separate different elements of an image. A layer can be compared to a transparency on which imaging effects or images are applied and placed over or under an image...

images between raster graphics

Raster graphics

In computer graphics, a raster graphics image, or bitmap, is a data structure representing a generally rectangular grid of pixels, or points of color, viewable via a monitor, paper, or other display medium...

editors. It is meant as a replacement for later versions of the Adobe PSD format. OpenRaster is still in development and so far is supported by a few programs. The default file extension for OpenRaster files is ".ora".

Background

For many years the Adobe Photoshop

Adobe Photoshop

Adobe Photoshop is a graphics editing program developed and published by Adobe Systems Incorporated.Adobe's 2003 "Creative Suite" rebranding led to Adobe Photoshop 8's renaming to Adobe Photoshop CS. Thus, Adobe Photoshop CS5 is the 12th major release of Adobe Photoshop...

PSD file format was used as a cross-application file format for layered images. Adobe allowed this by releasing the format's specifications publicly. However, in 2006 Adobe changed this license to only grant access to and use of the specifications and documentation "for the purposes of internally developing Developer Programs in connection with Adobe Software products and incorporating portions or all of the Sample Code into Developer Programs." In response to these restrictions, the OpenRaster format was proposed at the first Libre Graphics Meeting

Libre Graphics Meeting

The Libre Graphics Meeting is an annual convention for the discussion of free and open source software used with graphics; The first Libre Graphics Meeting was held in May 2006. Communities from Inkscape, GIMP, Krita, Scribus, sK1, Blender, Open Clip Art Library, Open Font Library, and more come...

at Lyon, France in the spring of 2006 and is drawn from the Open Document Format.

General

full freely available documentation
OpenDocument type of file format (archive with multiple files inside)
extensible, but private undocumented extensions should be excluded, any extension should be added to the spec and documentation of the file format
applications aren't expected to support all features of the file format, but when manipulating the file they shouldn't lose any information they can't handle

Metadata

storage of metadata
Metadata
The term metadata is an ambiguous term which is used for two fundamentally different concepts . Although the expression "data about data" is often used, it does not apply to both in the same way. Structural metadata, the design and specification of data structures, cannot be about data, because at...

using {XMP
Extensible Metadata Platform
The Adobe Extensible Metadata Platform is a standard, created by Adobe Systems Inc., for processing and storing standardized and proprietary information relating to the contents of a file....

- Dublin Core
Dublin Core
The Dublin Core metadata terms are a set of vocabulary terms which can be used to describe resources for the purposes of discovery. The terms can be used to describe a full range of web resources: video, images, web pages etc and physical resources such as books and objects like artworks...

- IPTC
IPTC Information Interchange Model
The Information Interchange Model is a file structure and set of metadata attributes that can be applied to text, images and other media types...

} tags
possibility of storing metadata tags per layer
storage of Exif tags
all text data in Unicode
Unicode
Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems...

(UTF-8
UTF-8
UTF-8 is a multibyte character encoding for Unicode. Like UTF-16 and UTF-32, UTF-8 can represent every character in the Unicode character set. Unlike them, it is backward-compatible with ASCII and avoids the complications of endianness and byte order marks...

or UTF-16)

Layers

storage of multiple layers
storage of each layer's coordinates
storage of blending (compositing) options for each layer
storage of adjustment layers
storage of layer effects
groups of layers
color information - profile, colorspace

Other

storage of paths, clipping paths, text on path
selections, masks
embedding documents within OpenDocument framework
support undo/history of commands/actions like PSD do

Proposals and extensions

Palette
Embed Fonts (Proposal to extension)
Multiple pages
Animation support using multiple pages and a timer like PSD do

Challenges

A major problem is that because all features aren't available in all the programs, image won't be displayed the same way in different applications, especially for adjustement/filters layers. And "viewer" apps like inkscape or scribus won't have any implementation at all of those features

A likely work-around is the optional storage of a redundant extra layer containing the fully rendered pixel data as seen after all image processing, or possibly a lower-resolution snapshot of it suitable for previewing and thumbnailing.

Different implementations levels might be defined, like, tiny, simple, small, normal, full and custom.

Application support

OpenRaster has limited support in a few graphics programs and among these its cross-application use is not seamless.
|-
!Application
!Status

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|MyPaint

MyPaint

MyPaint is a free software graphics application for digital painters, similar to Corel Painter.- History :The project has been under development since before August 11, 2004 * Version 0.1 was released March 12, 2005...

|Default working file format.

|-
|GIMP

GIMP

GIMP is a free software raster graphics editor. It is primarily employed as an image retouching and editing tool and is freely available in versions tailored for most popular operating systems including Microsoft Windows, Apple Mac OS X, and Linux.In addition to detailed image retouching and...

|Planned + external plug-in.

|-
|Krita

Krita

Krita is the digital painting and illustration software included based on the KDE Platform and Calligra Suite libraries. Designed as a digital painting and illustration suite, Krita is free software and distributed under GNU General Public License...

Pinta (software)

Pinta is a lightweight open-source, cross-platform bitmap image drawing and editing program inspired by Paint.NET, a similar image editing program which is limited to Microsoft Windows. Pinta aims to offer a free and open-source simpler alternative to GIMP on the GNOME desktop environment...

|Supported starting with version 0.4.

|-
|XnView

XnView

XnView is a cross-platform image viewer used for viewing, converting, organising and editing graphical & video files. It is free of charge for private, educational and non-profit organisations...

|Supported starting with version 1.98.1 >

External links

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.