[Lcms-user] Dealing with ICC CMYK profile

[jszczepanek <jsz...@ic...>]

 Hello everyone.
 My name is John and I am a student at Warsaw University of Technology 
 in Poland.
 Recently I have been working on my project from calculating methodes in 
 image processing.
 I am a fresh programmer in C++ (VS2012)
 I aim to develop RGB to CMYK convertion with using ICC profiles.
 I know that LittleCMS provide transform methodes but my supervisor 
 adviced me to create my own methodes and then optimize it, so I need to 
 dig deeper in ICC profile to create CMM conversion by myself.

 Unfortunately from the beginning I have some problems and I would like 
 to ask you for some help.

 I managed to read "B" Curves and Matrix from RGB ICC profile so I 
 managed to convert from RGB to XYZ (PCS). Then I convert XYZ to LAB 
 (XYZ2LAB methode) because LAB is color space of my CMYK ICC profile... 
 and now I get stuck.

 1. I cannot figure out what is CMM of my profile.
 As far as I know there should be some info in cmsICC Header struct 
 (cmsSignature  cmmId;  CMM for this profile), but I can not figure out 
 how to get this information.
 2. I use  cmsReadTag(hOutProfile,cmsSigBToA0Tag); to read BtoA0, and 
 the number of stages in Pipline is 3 but I do not know if it is:
 B, Matrix, M; or B, CLUT, A;  transformation.
 3. Also I have a problem to get real data from Stages of Pipline, how 
 can I recieve Curve or Matrix from this structure? Or I get the concept 
 wrong.

 I will be very grateful for any comments and tips how can I get 
 real/raw data to make a transform from LAB to CMYK by using Curves and 
 Matrix.

 Thank you in advance for your help.

 Best regards,
 Jan Szczepanek