Linux Color Management Hackfest Brno 2012 ended

Around a dozen people met inside the Red Hat offices in Brno last weekend. The attendees came from various distributions and projects to discuss and work on color management for Linux. Most people arrived at Thursday and we started immediately to brain storm ideas and share information.

I was quite shocked as I heard Dantii could not join us. Fortunately the last messages about him sound very encouraging. It is great that our community could in different ways help him and his family.

The basic concept we worked with during the hackfest, was the opt-out of colour management approach. That was visible in printing and in window manager colour management.

Printing people discussed the PDF/X OutputIntent. The concept was developed to overcome the current short commings in the cupsICCprofile, which is primarily a vendor solution for CUPS print servers and the colord user session hook inside CUPS server. The implementation of the concept was done inside libCmpx, which is basically a wrapper around Ghostscript, which does the majority of the work, and a interface to Oyranos. From the other side John Layt looked into that work and Krita new print colour management tab to understand the implications for the KDE/Qt print dialog. He discussed lively with Till Kamppeter, Richard Hughes, Chris Murphy and me on how to get forward with that. Richard wrote a proof of concept for on screen print simulation in GTK. Chris talked a lot about osX printing and did some testing there. His experience on other platforms than Linux helped us a lot to figure out, which path we want to go and way the make sense. I searched for some PDF’s showing the features we need. They can now be found on ColourWiki. Jaroslav Reznik printed them and Till tested them. Michael Vrhel from the Ghostscript project fixed already after the event all of the bugs, which Till worked on in Brno. We had the idea, that some PDF printers might be able to do the right thing with the OutputIntent themselves. While discussing on how to know about that capability, Till and Richard had a nice idea how to reduce code duplication inside the current set of Linux CUPS filters. In parts the Color Management Hackfest crossed over into a Printing Summit.

Jan Grulich started coding on KolorManager. He implemented a widget to show a 2D graph of a ICC profile inside the information tab. Sirko Kemter was not very happy about the colours inside the graph. So I adjusted them, but after the hackfest.

While working on that, Jan profiled his monitor using Dantii’s colord-kde. Yes, Lukáš Tinkl fixed it, so it can now create ICC profiles. We needed to hand massage the profile to get it into Taxi DB, and then thought, it would be good to download the fresh profile later through Oyranos. That worked fine on the command line. But inside KolorManager a selection that a profile is available for download from Taxi DB would be more appealing. Jan wanted to look into that, and I worked later on a API and code snippet for Oyranos.

By the way, the above screen shot is done using the new colour correction feature for KDE-4.10. You might see the strong colour cast in it. Dan Vrátil worked on undoing that cast inside KSnapshot using the actual monitor profile. The initial coding was fast. But he likes to get that working for multiple outputs too.

Casian Andrei, who did the KWin Color Correction project during this years GSoC, wrote some documentation about that newly added feature. While writing that and clarifying some points, we discussed the opt-out inside KWin and found that it is not yet present. Sig. But Casian had played with the idea already and said that per region opt-out would be trivial inside KWin and started to write on that feature during Sunday. In case that works out, it would be trivial to opt out inside existing applications. But we found as well, that for a perfect results only a blending in the correct colour space is needed during compositing. That can be implemented inside toolkits, which is not trivial, and can then be used together with the per window opt-out. That buys us some valuable time for the toolkits to become ready for full colour management support. Whether the same per region approach is easy enough to implement in Wayland needs to be seen.

Now back to profile distribution. Oyranos obtained a new backup tool for Taxi DB. And we counted already over 200 different ICC profiles in the online data base. Sirko Kemter and Daniel Jahre grabbed the taxi sources, installed MongoDB and worked on mostly basic stuff to add later more features. The online front end to the DB can be used on every platform for download and upload. Daniel and Sirko discussed how to temporarily store a ICC profile from the ColorHug LiveCD. We found that the data base can be used for very different things, e.g. distribution of spectral data sets for camera sensors.

Pippin worked since some time on improving the display of gradients on 8-bit driven monitors. He came up with a dithering approach and tested that using the Taxi DB profiles for the analysis of his implementation. That helped him to make the algorithm more robust even with strongly distorted monitor gamma curves. There is quite some interest inside the graphics designers community for his work to solve banding problems. We talked a bit about gegl and I found babl especially interesting. The small library does, what I call pixel layout conversions. Those are in part colour space conversions and encoding conversions. For better separating encoding, 8-bit versus 16-bit etc., from colour spaces, e.g. linear gamma + Rec709 primaries versus sRGB etc., we need better ICC profile analysis. Especially gamma analysis can be improved inside rendering pipelines. Beside discussing hardware stuff, spectral imaging, video processing and so on, he gave a small and very helpful introduction into colour theory, which was a eye opener for many of the colour management newcomers and thus very welcome.

We had a interesting discussion about financial implications of colour measurement hardware. My impression is the high costs and thus reduced availability for good colour measurement gear nags on the success and acceptance of ICC colour management in consumer and professional markets.

During the hackfest it was really a pleasure to have so many experts in the field in one room and work together in a highly productive atmosphere. Some of them I met the first time. So let me thank our sponsors Google, Red Hat and KDE for their generous support of the hackfest idea.

We all worked quite a lot and found such a event should not stay single. So we agreed already to arrange a one day track and one following day at LGM in Madrid / Spain 2013 under the OpenICC umbrella. I hope we will see then even more projects coming.

Oyranos-0.9.0 released

The first beta of the object oriented C API came out end of last month. It brings a bunch of changes. First, all known Oyranos using projects are updated or have patches available. While the internal changes where heavy weight, most external users had few lines to change. The new APIs where possible through a Google Summer of Code project of Yiannis Belias in  2011. Nearly all C object types and basic functions are generated from django templates, which are interpreted and  processed by the Grantlee engine and a customising plugin.

As we work on WM ICC colour management, we need more facilities to test workflows. In order to support that, the oyranos-icc tool was added and can generate 3D LUTs in various formats. Among them is hald and 3D texture. Te later format is used in CompICC and the new KolorServer of Casian Andrei. The 3D texture is stored as a PPM and can be loaded into the image_display example viewer and drives fast client side colour correction inside OpenGL. The same tool can be used to convert PPM and PNG files through ICC profiles including proofing and effect profiles, much like the C API allows.

The oyranos-profile-graph tool was already described in this blog. New is the generation of ICC profiles out of libRaw/dcraw camera matrices. That is a very nice fallback in case a camera RAW file has no custom profile available. This will not substitute DCP profiles, but is a step forward in integrating camera RAW workflows into ICC driven systems.

default ROMM RGB versus dcraw matrix derived colour space ICC profiles

 

 

Linux Color Management Hackfest 2012

The hackfest in Brno is approaching fast. I wrote earlier this year about the idea. It will happen from 9th until 12th November 2012 inside the Red Hat Czech office. Talks with our local organiser and various sponsors went good so far. People will code in Brno on various topics around color management in Linux.

The main focus looks like to be at applications, desktop and library integration. For the printing system and Taxi DB was good interest too. As the event is organised as a framework for attendees, each one will decide, what is best to do. After a morning meeting, where we can coordinate, we will likely split in smaller groups according to a choosen topic or move around as needed. We hope that works for all attendees. There are specialists present for many Linux color topics for discussion and of course color management newbies can ask them to effectively improve their project.

Little CMS 2.4 released

Version 2.4 is a featured release that introduces new functionality as
well as many performance and security improvements.

Main additions are:

  • Black point detection from the algorithm disclosed by Adobe
  • Added support for transforms on planar data with different stride
  • Added a new plug-in type for optimizing full transforms
  • Linear (gamma 1.0) profiles can now operate in unbounded mode
  • Added “half” float support

The last point of 16-bit floating point support is much requested from e.g. the Krita project.

 

OpenICC Google Summer of Code 2012 results

Google Summer of Code

Participation of the OpenICC group in the Google Summer of Code 2012 program was this year a great success. All projects reached their respective goals. Here a small summary:

Colour Management for Krita Printing
Joseph Simon worked on adaption and integration of his last years implementation for colour managed printing into Krita/Linux. The workflow is based on ICC profile injection into PDF through the means of a OutputIntent.

KWin Colour Correction
Casian Andrei’s KWin changes for ICC style colour correction in the GPU are reviewed upstream and his new code to the KolorManager code base waits just for approval. The concept follows the X Color Management spec. In contrast to the elder CompICC implementation is the KWin result highly modular and thus very flexible.

Simple Toolkit Abstraction
Nitin Chadas SimpleUI project for rendering a subset of XForms was written from
ground up and provides now backends for FLTK, Gtk and Qt. It needs a bit
of polishing to become useable.

Thanks to Google for providing the colour management and graphics community again a great chance to code and learn the open source way.

Linux Color Management Hackfest idea

Sirko brought up the idea to organise a hackfest together with developers of applications for Linux desktops and experts interested in colour management. The idea behind that event was to bring interested developers together, support them in implementing color management in their software and move forward that topic across desktops and distributions.

During the recent LGM we found a chance to involve Richard Hughes and planed together about what we like to do during the hackfest. We spotted three main areas of interest: desktop applications including window managers, web browsers and printing. These topics are already worked on, but in a scattered way.

As example, Gwenview is a really great application for managing pictures. But it has no color management implemented yet. Color management in KWin is worked on during the GSoC this year, but in the opposite color management in the compositing manager mutter on the GNOME side is far away as can be read here. Not many web browsers support color management and if they who do, it is often incomplete. The SVG v2 standard will for example introduce additional color management features compared to SVG v1. So it is now the right time to get these implemented in order to be well prepared. For the KDE printing stack there is also a GSoC project this year, but also the Linux Foundation has a working group for this topic.

So, by meeting in person in one place, we want to get something done and build a good understanding of the role of each participating group for a working end to end colour management.

The hackfest will very likely happen in Brno in the Czech Republic at the Red Hat offices. A good time appears later this year 16th till 19th November. Now we like to collect more ideas, speak to people and sort financial issues.

Colour Management Talk @ LinuxTag 2012

Logo LinuxTagEuropes biggest event arround Linux and Open Source – LinuxTag, is’nt far away anymore and Oyranos will participate on it. LinuxTag take its place in Berlin from 23.-26. May on the exhibition area arround the Funkturm. On saturday the 26th of May I will present together with Sirko an talk about colour management – “Bring Color To The Game“. The talk will not introduce Oyranos as CMS, it will more explain what color management is and about the actual status on free desktops. We want as well to talk about what a user needs to get colour management running. During LinuxTag I will be reachable on the openSUSE booth for questions and introduction into profiling and bring some colorimeters.

ArgyllCMS V1.4.0 Released

The new version of the cross platform Colour Management System comes with new features and bug fixes.

  • ccxxmake can create correction matrixes using a reference colorimeter
  • support JPEG in cctiff, tiffgamut and extracticc
  • support display calibration and profiling on display without VideoLUT
  • support directing colour patches to a web browser for measurements and profiling

The ChangeLog contains the full list of modifications.

About: ArgyllCMS is the primary tool set in the open source world to access colour measurement devices and to create ICC profiles. Together with it’s colour conversion and analysis capabilities it is located in the tool box of many colour management professionals. Several freely distributed graphical front ends exist for ease of handling.

OpenICC Google Summer of Code 2012 projects

OpenICC obtained three project slots for the Google Summer of Code 2012
stipends. That means three students can work again this year full time over
three summer months on colour management projects. Thanks to Google for
organising and sponsoring the program.

Here are in short the projects:

Joseph Simon will continue to work on PDF colour management for the
KDE/Linux printing stack. To have a real world project he choose to implement
Colour Management for Krita Printing.

Casian Andrej will work on ICC KWin colour correction using the X Color
Management spec. That way KWin gets a clear path toward consistent colour
output on the desktop.

Nitin Chada will work on different toolkit dependent renderers for a
XForms subset inside the Simple Toolkit Abstraction project. That standalone project shall enable modules to present
options inside dialogs or embedded in host applications.

Lets have a successful coding summer and deserve the trust Google putted in
the OpenICC organisation and with that in the participating students.