Contents

Babl is a dynamic, any to any, pixel format conversion library. It provides conversions between the myriad of buffer types images can be stored in. Babl doesn't only help with existing pixel formats, but also facilitates creation of new and uncommon ones.

GEGL uses babl both for enumeration of pixel formats as well as conversions between them.

Features

Download

The latest versioned development version of babl can be found in ftp://ftp.gtk.org/pub/babl/.

Babl development happens in GNOME Subversion in the babl module. It can be browsed online and checked out with:

svn co http://svn.gnome.org/svn/babl/trunk/ babl

The following is a list of the major changes that have gone into each babl release. If there are significant improvements to babl when a GEGL release is done a babl release is most often put out just prior to the GEGL release.

2007-01-07 babl-0.0.12
Speedups for GEGL Build environment fixes.
2006-xx-xx babl-0.0.10
Build environment fixes.
2006-12-29 babl-0.0.8
Made code adhere more strictly to C standard. Set the BABL_PATH based on build prefix
2006-10-09 babl-0.0.6
Build environment fixes. Fixed timing code for picking correct conversions.
2006-08-31 babl-0.0.4
Build environment fixes Reduced used/exposed API. Added GEGL speedup extension.
2005-0x-xx babl-0.0.2 Green fish release
Initial release.
2005-08-xx babl-0.0.1
Development release of babl, minimal working configuration for RGB, CMYK and YCbCr for 8bit 16bit float and double. Emphasis is on precision and clarity of code not speed.

Documentation

When using BablFishes to do your conversions, you request a fish to convert between two formats, and an optimal fish to babls capability is provided that you can use to do your conversions. Babl also provides the capability to describe new formats based on a vocabulary of user registered color models and data types.

Babl provides a base vocabulary in BablBase and some extensions that are thought to be generally useful.

When performing further extensions to the vocabulary of babl, the internal consistency is governed by reference conversions that operate on double (64 bit floating point values). The only color model created during BablCore bootstrap is RGBA (linear light RGB, 0.0 - 1.0, with a linear 0.0 - 1.0 opacity channel) backed by the double datatype.

If babls conversion isn't fast enough, you can provide your own conversion shortcut between two formats. The registered shortcut might also be used by babl as an intermediate conversion when constructing BablFishes for other conversions.

Babl extensions are shared objects. If you have already developed some fast conversion functions, wrapping them as babl extensions should not take much time and will speed up babl for other users as well.

Usage

The simplest scenario for using babl is converting between linear buffers represented by an existing BablPixelFormat.

babl_process (babl_fish ("srgb", "CIE Lab float"),
              srgb_buffer, lab_buffer,
              pixel_count);

If the existing pixel formats are not sufficient for your conversion needs, new ones can be created on the fly. The constructor will provide the prior created one if duplicates are registered.

format = babl_format_new (babl_model ("R'G'B'"),
                          babl_type ("u8"),
                          babl_component ("B'"),
                          babl_component ("G'"),
                          babl_component ("R'"),
                          NULL);
babl_process (babl_fish (source_format, destination_format),
              source_buffer, destination_buffer,
              pixel_count);

Vocabulary


+-
bits
64
bytes
8
bits
32
bytes
4
bits
8
bytes
1
bits
8
bytes
1
bits
8
bytes
1
bits
16
bytes
2
bits
32
bytes
4
bits
8
bytes
1
bits
8
bytes
1
bits
16
bytes
2
bits
16
bytes
2
components
R
G
B
A
components
R
G
B
components
Ra
Ga
Ba
A
components
R'
G'
B'
components
R'
G'
B'
A
components
R'a
G'a
B'a
A
components
Y
components
Y
A
components
Ya
A
components
Y'
components
Y'
A
components
Y'a
A
components
Y'
Cb
Cr
components
Y'
Cb
Cr
A
components
cyan
magenta
yellow
key
components
CIE L
CIE a
CIE b
components
CIE L
CIE a
CIE b
A
bytes/pixel
32
model
RGBA
components
doubleR
doubleG
doubleB
doubleA
bytes/pixel
32
model
R'G'B'A
components
doubleR'
doubleG'
doubleB'
doubleA
bytes/pixel
32
model
R'aG'aB'aA
components
doubleR'a
doubleG'a
doubleB'a
doubleA
bytes/pixel
3
model
R'G'B'
components
u8R'
u8G'
u8B'
bytes/pixel
4
model
R'G'B'A
components
u8R'
u8G'
u8B'
u8A
bytes/pixel
16
model
RGBA
components
floatR
floatG
floatB
floatA
bytes/pixel
12
model
RGB
components
floatR
floatG
floatB
bytes/pixel
16
model
Y'aA
components
doubleY'a
doubleA
bytes/pixel
8
model
Y
components
doubleY
bytes/pixel
16
model
YA
components
doubleY
doubleA
bytes/pixel
24
model
Y'CbCr
components
doubleY'
doubleCb
doubleCr
bytes/pixel
32
model
Y'CbCrA
components
doubleY'
doubleCb
doubleCr
doubleA
bytes/pixel
3
model
Y'CbCr
components
u8-lumaY'
u8-chromaCb
u8-chromaCr
bytes/pixel
16
model
R'G'B'A
components
floatR'
floatG'
floatB'
floatA
bytes/pixel
8
model
R'G'B'A
components
u16R'
u16G'
u16B'
u16A
bytes/pixel
16
model
R'aG'aB'aA
components
floatR'a
floatG'a
floatB'a
floatA
bytes/pixel
8
model
R'aG'aB'aA
components
u16R'a
u16G'a
u16B'a
u16A
bytes/pixel
4
model
R'aG'aB'aA
components
u8R'a
u8G'a
u8B'a
u8A
bytes/pixel
12
model
R'G'B'
components
floatR'
floatG'
floatB'
bytes/pixel
6
model
R'G'B'
components
u16R'
u16G'
u16B'
bytes/pixel
8
model
Y'A
components
floatY'
floatA
bytes/pixel
8
model
Y'aA
components
floatY'a
floatA
bytes/pixel
4
model
Y'
components
floatY'
bytes/pixel
4
model
Y'A
components
u16Y'
u16A
bytes/pixel
4
model
Y'aA
components
u16Y'a
u16A
bytes/pixel
2
model
Y'
components
u16Y'
bytes/pixel
2
model
Y'A
components
u8Y'
u8A
bytes/pixel
2
model
Y'aA
components
u8Y'a
u8A
bytes/pixel
1
model
Y'
components
u8Y'
bytes/pixel
12
model
Y'CbCr
components
floatY'
floatCb
floatCr
bytes/pixel
16
model
Y'CbCrA
components
floatY'
floatCb
floatCr
floatA
bytes/pixel
8
model
RGBA
components
u16R
u16G
u16B
u16A
bytes/pixel
4
model
RGBA
components
u8R
u8G
u8B
u8A
bytes/pixel
16
model
RaGaBaA
components
floatRa
floatGa
floatBa
floatA
bytes/pixel
8
model
RaGaBaA
components
u16Ra
u16Ga
u16Ba
u16A
bytes/pixel
4
model
RaGaBaA
components
u8Ra
u8Ga
u8Ba
u8A
bytes/pixel
6
model
RGB
components
u16R
u16G
u16B
bytes/pixel
3
model
RGB
components
u8R
u8G
u8B
bytes/pixel
8
model
YA
components
floatY
floatA
bytes/pixel
8
model
YaA
components
floatYa
floatA
bytes/pixel
4
model
Y
components
floatY
bytes/pixel
4
model
YA
components
u16Y
u16A
bytes/pixel
4
model
YaA
components
u16Ya
u16A
bytes/pixel
2
model
Y
components
u16Y
bytes/pixel
2
model
YA
components
u8Y
u8A
bytes/pixel
2
model
YaA
components
u8Ya
u8A
bytes/pixel
1
model
Y
components
u8Y
bytes/pixel
32
model
CMYK
components
doublecyan
doublemagenta
doubleyellow
doublekey
bytes/pixel
16
model
CMYK
components
floatcyan
floatyellow
floatmagenta
floatkey
bytes/pixel
4
model
R'aG'aB'aA
components
u8B'a
u8G'a
u8R'a
u8A
bytes/pixel
4
model
R'G'B'
components
u8B'
u8G'
u8R'
u8PAD
bytes/pixel
12
model
CIE Lab
components
floatCIE L
floatCIE a
floatCIE b
bytes/pixel
32
model
CIE Lab alpha
components
doubleCIE L
doubleCIE a
doubleCIE b
doubleA
bytes/pixel
3
model
CIE Lab
components
CIE u8 LCIE L
CIE u8 abCIE a
CIE u8 abCIE b
bytes/pixel
6
model
CIE Lab
components
CIE u16 LCIE L
CIE u16 abCIE a
CIE u16 abCIE b
bytes/pixel
24
model
CIE Lab
components
doubleCIE L
doubleCIE a
doubleCIE b
bytes/pixel
32
model
CIE Lab alpha
components
doubleCIE L
doubleCIE a
doubleCIE b
doubleA

Shortcut coverage

The diagram shown below visualizes the coverage of current shortcut conversions. A DHTML version is also available.


 ··  ·▁····· ▁ ▂  ▂              ▁             ·       ··── 0 RGBA double
· ▁  ▁▂▁▁▁▁▁ · ▁  ▁              ▂             ▁       ▁▁── 1 R'G'B'A double
·▁   ▁▂▁▁▁▁▁ ▂ ▃  ▃              ▂             ▁       ▁▁── 2 R'aG'aB'aA double
▁▂▂ ··▁▂▂▂▂▂ ▁ ▁ ··              ·             ▂       ▂▂── 3 R'G'B' u8
▁▁▂· ·▁▂▂▂▂▂ · ▁  ▁              ▁             ▂       ▂▂── 4 R'G'B'A u8
·▁▁   ·▁▁▁▁▁ ▂ ▃  ▃              ·             ▁       ▁▁── 5 RGBA float
▁▂▂  · ▂▂▂▂▂ ▃                   ·             ▂       ▂▂── 6 RGB float
·▁▁  ▁▂ ▁▁▁▁ ▂ ▃  ▃              ▂             ▁       ▁▁── 7 Y'aA double
·▁▁  ▁▂▁ ▁▁▁ ▂ ▃  ▃              ▂             ▁       ▁▁── 8 Y double
·▁▁  ▁▂▁▁ ▁▁ ▂ ▃  ▃              ▂             ▁       ▁▁── 9 YA double
·▁▁  ▁▂▁▁▁ ▁ ▂ ▃  ▃              ▂             ▁       ▁▁──10 Y'CbCr double
·▁▁  ▁▂▁▁▁▁  ▂ ▃  ▃              ▂             ▁       ▁▁──11 Y'CbCrA double
                                                         ──12 Y'CbCr u8
▁·▂  ▂▃▂▂▂▂▂   ·  ·              ▃             ▂       ▂▂──13 R'G'B'A float
▂▁▃  ▃ ▃▃▃▃▃ · ▁  ▁                            ▃       ▃▃──14 R'G'B'A u16
                                                         ──15 R'aG'aB'aA float
               ·                                         ──16 R'aG'aB'aA u16
               ·                                         ──17 R'aG'aB'aA u8
▂▁▃  ▃ ▃▃▃▃▃ · ·                               ▃       ▃▃──18 R'G'B' float
▃▂           ▁ ▁  ·                                      ──19 R'G'B' u16
▂▁▃  ▃ ▃▃▃▃▃ · ▁  ▁  ·· ▂  ▁                   ▃       ▃▃──20 Y'A float
▃▂           ▁ ·  ▂ · ▁ ▁  ·                             ──21 Y'aA float
▃▂           ▁ ▁  · ··                                   ──22 Y' float
▃▂           ▁ ▂  ▂ ·▁▁ ▃  ▂                             ──23 Y'A u16
 ▃           ▂ ▁  ▃ ▁·▂    ▁                             ──24 Y'aA u16
 ▃           ▂ ▂  ▁ ▁▁·                                  ──25 Y' u16
▃▂           ▁ ▂  ▂ ·▁▁ ▃  ▂                             ──26 Y'A u8
 ▃           ▂ ▁  ▃ ▁·▂ ·                                ──27 Y'aA u8
 ▃           ▂ ▂  ▁ ▁▁·                                  ──28 Y' u8
▃▂           ▁ ▁  ·                                      ──29 Y'CbCr float
▂▁▃  ▃ ▃▃▃▃▃ · ▁  ▁                            ▃       ▃▃──30 Y'CbCrA float
▁▂▂  ·▁▂▂▂▂▂ ▃                   ▁             ▂       ▂▂──31 RGBA u16
▁▂▂  ·▁▂▂▂▂▂ ▃                   ▁   ·         ▂       ▂▂──32 RGBA u8
                                                         ──33 RaGaBaA float
                                 ·                       ──34 RaGaBaA u16
                                 ·                       ──35 RaGaBaA u8
▂▃▃  ▁·▃▃▃▃▃                     ▁             ▃       ▃▃──36 RGB u16
▂▃▃  ▁·▃▃▃▃▃                    ·▁ ·           ▃       ▃▃──37 RGB u8
▁▂▂  ·▁▂▂▂▂▂ ▃                   ▁     ··      ▂       ▂▂──38 YA float
▂▃▃  ▁▂▃▃▃▃▃                     ·    · ▁      ▃       ▃▃──39 YaA float
▂▃▃  ▁·▃▃▃▃▃                     ▁    ··       ▃       ▃▃──40 Y float
▂▃▃  ▁▂▃▃▃▃▃                     ▂    ·▁▁      ▃       ▃▃──41 YA u16
▃    ▂▃                          ▁    ▁·▂                ──42 YaA u16
▃    ▂▁                          ▂    ▁▁·                ──43 Y u16
▂▃▃  ▁▂▃▃▃▃▃                     ▂    ·▁▁      ▃       ▃▃──44 YA u8
▃    ▂▃                          ▁    ▁·▂                ──45 YaA u8
▃    ▂▁                          ▂    ▁▁·                ──46 Y u8
·▁▁  ▁▂▁▁▁▁▁ ▂ ▃  ▃              ▂                     ▁▁──47 CMYK double
                                                         ──48 CMYK float
                                                         ──49 B'aG'aR'aA u8
                                                         ──50 B'aG'aR'aPAD u8
                                                         ──51 CIE Lab float
                                                         ──52 CIE Lab alpha float
                                                         ──53 CIE Lab u8
                                                         ──54 CIE Lab u16
·▁▁  ▁▂▁▁▁▁▁ ▂ ▃  ▃              ▂             ▁        ▁──55 CIE Lab double
·▁▁  ▁▂▁▁▁▁▁ ▂ ▃  ▃              ▂             ▁       ▁ ──56 CIE Lab alpha double
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||
||||||||||11111111112222222222333333333344444444445555555
012345678901234567890123456789012345678901234567890123456
total length: 1501
total cost  : 798591

Extending

For samples of how the current internal API specification of data types, color models, and conversions look in the extensions/ directory. The tables in this HTML file is directly generated based on the data registered by BablCore (double and RGBA), BablBase (core datatypes, and RGB models), extensions (CIE Lab, naive CMYK, various shortcut conversions).

TODO

Copyright

Babl is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

Authors

Øyvind Kolås pippin@gimp.org
Lead developer.
Sven Neumann sven@gimp.org
Build sanity.
Michael Natterer mitch@gimp.org
Build sanity.
Kevin Cozens
Build sanity.
Tim Mooney
Portability fixes.
Michael Schumacher schumaml@cvs.gnome.org
win32 support for dynamic extensions.
Portability fixes.
/babl-0.0.15