Interpolation wars

15 days after the release, one issue in the packaging and some glitches on linkicc. Still no big bugs. At least the reported  ones are not such big to need a 2.1 release... yet.

Little CMS releases have been historically dropped each 6 months, so 2.1 should come on October-November more or less. I have a talk on the ICC DevCon on November, so it would be nice to have 2.1 released to at that time.

Otherwise the git is alive and I'm periodically committing  fixes to it. If you are using Little CMS code and don't have dependencies on linux distributions, I would recommend to use git code if possible.

One of those small glitches found is a weird error that was reported by a HP folk days ago. He was seeing
small differences on a CMYK profile when upgrading from 1.19 to 2.0

So, after investigation, I found the reason of those differences: Tetrahedral interpolation being used in 2.0 and Trilinear interpolation in 1.19. Tetrahedral was patented time ago, but now the patent has expired.

In fact, I did see such issue many years ago. On LUT elements being indexed by Lab colorspace, Tetrahedral does not work well. I suspect that's because Luma is uncentered (L is on one axis)

First thing to discard was a code bug. So I tried Max Derhak's SampleICC. To my astonishment, SampleICC is also using trilinear by default. Tried to modify Max code to do the interpolation as tetrahedral and... bingo! the same "bad" results as Little CMS. Up to four decimals. So here we go, the "bug" is in the interpolation algorithm. I checked PhotoShop CS4. It seems to be also using trilinear as well.

Now I have committed those changes to git. Note however, that your are not going to notice any difference but in very few profiles, and even in this case, maximum difference is about 2-3 digital counts (0.5 dE)

 I am pleased to the announce the release 2.0 of the LittleCMS open source color engine.

 Version 2.0 is an important milestone, among other improvements, it delivers: 

• Full implementation of the ICC standard 
• Improved documentation 
• Better portability 
• Easier extensibility

Migration to 2.x branch is highly encouraged. 

 

Little CMS intends to be a small-footprint color management engine, with special focus on accuracy and performance. It uses the International Color Consortium standard (ICC), which is the modern standard when regarding to color management. The ICC specification is widely used and is referred to in many International and other de-facto standards.

 

For more information, please take a look on: 

Main site: 

http://www.littlecms.com/
Downloads:
http://www.littlecms.com/download.html

 

LittleCMS 2.0 release date

Beta 3 seems stable enough, so now I can set a final release date for lcms2.

LittleCMS 2.0 will hopefully be released on Saturday, May-8-2010

So, if you have found a bug, inconsistency, etc. Please let me know ASAP. Code is now frozen and I will start the final qualification phase. All change requests will be studied before commit, just to minimize risk.  Thanks again to all people that has contributed to this project!

Beta3 and release candidate

Here is beta3. We are almost done, so this is the release candidate.

• All known bugs are fixed.
• There are some improvements in CMYK interpolation, it is about 20% faster 
• jpgicc can now apply devicelinks without chrashing
• Matlab support is there!

Final release will follow in a month, so if you want to check the CMM in your application, now is a good time to do so. The code seems stable enough,  and you will catch small issues .

Beta 2 is ready

Time for a new beta. First one was very successful and several important bugs were found and fixed.

Beta2 will focus on quality and documentation, and will rest for a month.

I will give frequent updates on the status of the beta. You can download it from the link on the right.

xput comparative 1.19 vs. 2.0

Here is the comparative for the code in git. I will publish beta2 in a couple of days. As you can see the xput improvements are considerable.

1.19
-----

16 bits on CLUT profiles                     : 10.6667 MPixel/sec.
8 bits on CLUT profiles                      : 9.75015 MPixel/sec.
8 bits on Matrix-Shaper profiles             : 3.8638 MPixel/sec.
8 bits on SAME Matrix-Shaper profiles        : 4.28495 MPixel/sec.
8 bits on Matrix-Shaper profiles (AbsCol)    : 10.4507 MPixel/sec.
16 bits on Matrix-Shaper profiles            : 3.92349 MPixel/sec.
16 bits on SAME Matrix-Shaper profiles       : 3.96924 MPixel/sec.
16 bits on Matrix-Shaper profiles (AbsCol)   : 10.6667 MPixel/sec.
8 bits on curves                             : 4.33839 MPixel/sec.
16 bits on curves                            : 4.3944 MPixel/sec.
8 bits on CMYK profiles                      : 4.09626 MPixel/sec.
16 bits on CMYK profiles                     : 3.96924 MPixel/sec.
8 bits on gray-to-gray                       : 24.3902 MPixel/sec.
8 bits on SAME gray-to-gray                  : 24.3902 MPixel/sec.


2.0
----

16 bits on CLUT profiles                     : 10.1394 MPixel/sec.
8 bits on CLUT profiles                      : 10.6667 MPixel/sec.
8 bits on Matrix-Shaper profiles             : 26.2726 MPixel/sec.
8 bits on SAME Matrix-Shaper profiles        : 30.1318 MPixel/sec.
8 bits on Matrix-Shaper profiles (AbsCol)    : 10.5541 MPixel/sec.
16 bits on Matrix-Shaper profiles            : 10.2433 MPixel/sec.
16 bits on SAME Matrix-Shaper profiles       : 9.84615 MPixel/sec.
16 bits on Matrix-Shaper profiles (AbsCol)   : 10.6667 MPixel/sec.
8 bits on curves                             : 30.0752 MPixel/sec.
16 bits on curves                            : 35.3201 MPixel/sec.
8 bits on CMYK profiles                      : 4.19727 MPixel/sec.
16 bits on CMYK profiles                     : 4.26667 MPixel/sec.
8 bits on gray-to-gray                       : 40.9207 MPixel/sec.
8 bits on SAME gray-to-gray                  : 40.9207 MPixel/sec.
8 bits on CMYK profiles                      : 4.3573 MPixel/sec.
16 bits on CMYK profiles                     : 4.55192 MPixel/sec.
8 bits on gray-to-gray                       : 39.312 MPixel/sec.
8 bits on SAME gray-to-gray                  : 40.9207 MPixel/sec.

Speed measurements

Here are some performance numbers, measured on my laptop. This is a pretty old compaq nc6400, Dual core T2300E (1.66GHZ) so it should rock in a modern machines. Note how fast transforms go when both profiles are implemented as matrix shaper. The measurements are using the code on git.

16 bits on CLUT profiles.. 5.95238 Mpixel/sec.
8 bits on CLUT profiles...10.5541 Mpixels/sec.
8 bits on Matrix-Shaper profiles..27.6817 Mpixels/sec.
8 bits on SAME Matrix-Shaper profiles...36.5297 Mpixels/sec.
8 bits on curves... 29.2505 Mpixels/sec.
8 bits on Matrix-Shaper profiles (AbsCol)...27.6817 Mpixels/sec.
16 bits on curves... 37.9147 Mpixel/sec.
8 bits on CMYK profiles... 8.90373 Mpixels/sec.
16 bits on CMYK profiles...4.45186 Mpixel/sec.
8 bits on gray-to-gray conversions.. 32.9897 Mpixels/sec.
8 bits on same gray-to-gray conversions ...39.312 Mpixels/sec.

Fixes on github

Ok, that seems to be working. I have received a couple of bug reports. Very helpful .There are now two nasty bugs less in the code base. Gray profiles were broken. That didn't work at all. I wonder how that passed the regression tests... ok, there was no regression tests for gray profiles. Now that is fixed as well. I still have to review documentation for some typos, but I think this can wait.

The latest (fixed) code is in the git. Or you can wait for beta2, which will be available on March.


http://github.com/mm2/Little-CMS

LittleCMS 2 on github

So here you go:

http://github.com/mm2/Little-CMS

You can review all files in a nice web page and also that makes fair easy to send patches. Many thanks to Richard Hughes for this nice idea!

You can also review the documentation in such way. It is located on 'doc' folder. The tutorial is a good starting point.

Little CMS 2.0 beta 1 is available!

Yes, that is. After so much time, all code, documentation, testbed, utilities... all is in the box, and all is working!

In one day or two I will announce the beta availability to the lcms mailing list, but meanwhile, you can be the very first to try it.

http://www.littlecms.com/lcms2-2.0beta1.tar.gz

Enjoy!

Include files

Any application using LittleCMS 2 has to include just one header.

#include “lcms2.h”

The header has been renamed to lcms2.h in order to improve the adoption of version 2. In fact, both Little CMS 1.x and 2.0 can coexist installed in same machine. This is very important on platforms like linux, where LittleCMS is nested deep in the dependency tree. Little CMS 2 no longer relies on icc34.h or any file coming from ICC. All costants are now prefixed by “cms” and there is one license for all package.

Lcms2.h does expose the API, and only the API. Unlike 1.xx series, all internal functions are no longer accesible for client applications.

A special case are the LittleCMS plug-ins. Those constructs can access more functions that the API, just because they are supposed to access Little CMS internals to add new functionality. There is a specialized include file for that:

#include “lcms2_plugin.h”

This file should only be included when defining plug-ins. It defines some additional functions and is described in the LittleCMS2.0 Plugin API document.

Requeriments

In order to improve portability and minimize code complexity, LittleCMS 2.0 requires a C99 compliant compiler. This requirement has been relexed on Microsoft’s Visual Studio because its wide adoption by industry (VC is not fully C99 compliant). Borland C 5.5 (available for free) has been tested and found to work Ok. gcc and the Intel compiler does work ok.