>I'm sorry for bombarding you with half a dozen questions ;-) No... I am who should be sorry for not being able to answer all lcms related questions, so apologizes to anybody who got no response. But lcms is a non-commercial project, and despite the kind sponsoring I'm getting from HP, I must earn some money too :-) So, most times I'm short of time and leave questions already discussed without response. Oh, well.
>An extended profile is a scanner profile created with a Level >adjustment in the target scan. The target scan can be extended in the >highlights or in the shadows or in both. >The target scan is lighten/darken up a little bit prior to feeding it to >the Profiling software. The reference file IS NOT CHANGED though. >If extending the shadows, for instance RGB=10 is mapped to 0. As a >result, the profiling software will be fooled into believing that the >scanner is inherently dark and generate a profile which tends to lighten >the image substantially." This is exactly what "push endpoints" option is doing. But one must be carefull in doing that, any displacement greater than 5% would probably introduce artifacts. Regarding the gamma 1.0 question, first make sure to use 16 bits TIFF when doing so. Gamma 1.0 + 8 bits = posterization. Also, since Lab exhibits a gamma of 3.0, so the "impedance mismatch" is less when using gamma encoded images. My advice would be to use gamma 2.2 or even more where possible, and leave gamma 1.0 for very special cases, like camera RAW, for example. Marti. ----- Original Message ----- From: "T E Schmitz" <[EMAIL PROTECTED]> To: "lms mailing list" <[EMAIL PROTECTED]>; "Marti Maria" <[EMAIL PROTECTED]> Sent: Wednesday, February 18, 2004 2:53 PM Subject: "extended" profiles Hello Marti, I'm sorry for bombarding you with half a dozen questions ;-) Here's another one and I'd be interested in your opinion on the topic: I have seen the following technique for so-called extended profiles described: "An extended profile is a scanner profile created with a Level adjustment in the target scan. The target scan can be extended in the highlights or in the shadows or in both. The target scan is lighten/darken up a little bit prior to feeding it to the Profiling software. The reference file IS NOT CHANGED though. If extending the shadows, for instance RGB=10 is mapped to 0. As a result, the profiling software will be fooled into believing that the scanner is inherently dark and generate a profile which tends to lighten the image substantially." I have played with a shadow extended profile but while it indeed lightens a dark image it also very often introduces posterization. -- Regards, Tarlika Elisabeth Schmitz ------------------------------------------------------- SF.Net is sponsored by: Speed Start Your Linux Apps Now. Build and deploy apps & Web services for Linux with a free DVD software kit from IBM. Click Now! http://ads.osdn.com/?ad_id=1356&alloc_id=3438&op=click _______________________________________________ Lcms-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/lcms-user
