[Lcms-user] Using CreateTransform in LCMS1 and LCMS2
An ICC-based CMM for color management
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From: Lee B. <le...@bo...> - 2013-01-28 12:57:04
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Hi, I'm in the process of updating an application that uses LCMS to do colour transformation to LCMS2 and have a problem. Converting a CMYK value to Lab gives quite different values using the same profile and (as far as I can tell) the same settings. LCMS2 transform function is this: return LCMS2TransformMBS.CreateTransform(p,LCMS2MBS.kTYPE_CMYK_16,lcms2labprofile,LCMS2MBS.kTYPE_Lab_16,3) LCMS1 Transform function is this: return LCMSMBS.CreateTransform(p,LCMSMBS.TYPE_CMYK_16,lcmslabprofile,LCMSMBS.TYPE_Lab_16,3) where p is an opened CMYK ICC profile, lcmslabprofile and lcms2labprofile is a simple CreateLab4Profile with no arguments. Using these transforms with a CMYK value of 0,0,0,0 (or any CMYK value) gives different Lab Values - up to about 1.5dEab. Viewing the memoryblock I get back when calling the transform shows the values are different too. LCMS1 values match very well those I get when using the Apple ColorSync utility. Hope someone can help Regards, Lee Badham www.bodoni.co.uk | www.presssign.com |