Hi Debora, ICC Spec is not little complex... is VERY complex!
I have spent 5 years in developing lcms at its current state, and still there are some arcane aspects of the ICC spec that are not fully implemented. The goal of lcms library is to hide such complexities and provide a higher-level point of view to those of us dealing with ICC profiles in real world. Of course, a bit of understanding of ICC spec does help, but most times you don't need that. So... if you are using lcms, you need not to worry about if a given profile is implemented by using matrix-shaper and curves, or LUT, or whatever. lcms handles profiles as "black boxes". You only need to create color transforms between profiles and apply these transforms to your raster data. Now for your specific questions: > what the black point is used for? The black point is the darkest neutral color a given device can render. You need not to worry on that, this is an info contained in the profile. The CMM (lcms) can use the black point to do what is know as "Black point compensation", which is nothing but a dynamic contrast adjustment. You surely would find a lot of info just searching the words "black point compensation". >What is the shaper matrix and the RGB curves I found in some tag in the profile? Again, you need not to worry on that. This profile is implemented by using a matrix plus a set of curves but a profile can be implemented in a lot of different ways. lcms handles all this stuff for you. >Which is the best intent for my purpose(I need to compare printing, and notice if >there are changes in color)? If you are comparing printed media, use relative colorimetric. If you want nice printouts, use perceptual. Relative colorimetric is for precision, perceptual is for eye candy, Saturation is almost never used and absolute colorimetric is for very specific scenarios. Don't use absolute colorimetric until you fully understand the chromatic adaptation effect. Else you will end in huge yellow or blue casts. Hope this helps Marti Maria The little cms project http://www.littlecms.com [EMAIL PROTECTED] ----- Original Message ----- From: Debora Vanni To: lcms-list Sent: Thursday, October 30, 2003 4:35 PM Subject: [Lcms-user] Help on ICCprofile I have some problem with ICC profile. I've just begun to use ICC profile and I read ICC specifications(www.color.org) but they are a little complex. I search around in the web, but could anybody suggest me a site or book with all the information I need? I mean, somenthing with a beginning and an end! I still don't know a lot of thing: what the black point is used for?What is the shaper matrix and the RGB curves I found in some tag in the profile?Which is the best intent for my purpose(I need to compare printing, and notice if there are changes in color)? I used Lcms library successfully, but I don't know exactly how to use it. Thanks Debora ------------------------------------------------------- This SF.net email is sponsored by: SF.net Giveback Program. Does SourceForge.net help you be more productive? Does it help you create better code? SHARE THE LOVE, and help us help YOU! Click Here: http://sourceforge.net/donate/ _______________________________________________ Lcms-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/lcms-user
