Actually it is a lot more simple. It has no meaning. Is just a sort of used defined cargo that you can use on your convenience. It has no relationship with threads, but can be used to store information about the thread.
Obviously you can ignore it if wish so. Then, by default this void pointer is set to NULL when creating the transform or opening the profiles.
In this way the threads, processes or wathever that are using the profiles and transforms can retrieve the value. It is just a way to store a 32 bit value along the handles.
On the other hand we have the 1-pixel cache. This is very convenient on slow interpolation methods when most of the pixels in the image are similar. Ok, you can use a semaphore the pthreads or just get rid of the cache enterely.
Please note that in some situations the cache is not used at all, i. On CMYK trilinear, cache is being used as interpolation tends to be slow. So, to answer your questions: If you use redundant transforms, you need not to worry about anything as each transform is using different cache. May be fast, but this is big a waste of memory.
If you share the same transform on several threads, which is very efficient, you have either to disable the cache or to enable pthreads. I would reccomend to disable the cache, the performance gain when using multiple threads is huge, the performance gain when using cache is small. If you need more performance, just add more threads. You have not to use cmsCreateTransformTHR, this is just a way to add a user-defined variable to the handle, and finally cmsDoTransform does not have any ContexID, the error reports the ContextID associated with the transform being used.
As a hint, ContexID are more useful when you want write a memory management plug-in to specialize memory mangement for multithreading, as the memory management pluging does recive ContextID when a memory operation is requested. The testebed application does use this feature to check memory consistency. Posted by Marti Maria at PM 12 comments:. Labels: Threads. Friday, December 10, Absolute colorimetric intent. Kai-Uwe Behrmann has found a nasty bug in 2.
Too bad. Well, It is not so terrible because it only affects the combination of abs. The specs on ICC V4 are pretty messed out when regarding to absolute colorimetric intent. There is now something called "ICC absolute", which is same that relative on display profiles and preserves paper white on output profiles.
Basically the observer is assumed to be fully adapted to whatever illuminant being used to create the profile, this has severe implications on monitor profiles, and no effect on printer profiles measured under D So right now we have the v2 absolute, wich says nothing about the observer adaptation state and v4 absolute which assumes full adaptation. I tried to do my best in supporting all modes v2 and v4 by implementing what the white paper below describes, a knob to adjust the degree of chromatic adaptation, a feature that may be useful for match-to-screen applications.
Word wrap license file. Jan 21, Feb 8, Nov 2, Remove all autotools files. Revert autotools files. Jun 27, Nov 1, View code.
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. Check the tutorial for a exhaustive list of features. By Marti Maria on September 9, It is Browser color management check day! As some users asked for this, I am recovering an old test I posted in lcms blog many years ago.
Basically, it uses special images with crafted embedded profiles. If profiles are correctly honored, a text will show up. But not all web browsers behave equally. Here are the old tests. They only check V2 compatibility. No surprises. Plug-in reference advanced CIC 18 paper on unbounded mode. Black point compensation testing. Mailing list lcms-user list on SourceForge.
Widely portable. Written in C Easy to use. Handles a wide range of pixel formats. Supports all kind of profiles, including named color. Can write profiles as well. Full multicolor support, up to 15 inks. Black point compensation. Black preservation on CMYK. Handles incomplete state of adaptation on absolute intents. Gamut checking.
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