Re: [Lcms-user] vgct tags
Hi, I looked at the LCMS docs and it has nothing about vgct tags lcms does currently NOT implement it because it is not on ICC spec. Alas, I'm a bit critical on such practices. Using this kind of stuff will make profiles active in the sense they are no longer a characterization of the hardware but a way to set specific configurations. I have seen many times desktops completely ruined by different software, each one trying to load its own vgct profile. Also, this is hardly non-portable and very hardware specific. The whole point of this tag is specify a set of curves for loading the hardware gamma ramp. But this puts hardware in half way since primaries are not modified at all, so the CMM has still some work to do. At that point I think this is useless, since non-color managed apps will continue displaying wrong colors and color-managed ones will continue processing the raster data. Exactly the same amount of work that doing all conversion, including gamma ramp. Some people would argue its is better half color management that nothing at all, but at that point the topic is no longer on color management, so let's forgot the whole stuff. I have added the tag signature in lcms.h, but quite probably this is all the support 1.15 will include. Regards -- Marti Maria The littlecms project. www.littlecms.com - Original Message - From: Hal V. Engel [EMAIL PROTECTED] To: lcms-user@lists.sourceforge.net Sent: Sunday, October 09, 2005 10:09 PM Subject: [Lcms-user] vgct tags I would like to setup LPROF so that it will create vgct tabs in monitor profiles. I looked at the LCMS docs and it has nothing about vgct tags there so I am not sure where to begin. Does anyone here know anything about this? If so could you point me to sources of information about this to help me get started? Thanks, Hal --- This SF.Net email is sponsored by: Power Architecture Resource Center: Free content, downloads, discussions, and more. http://solutions.newsforge.com/ibmarch.tmpl ___ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user -- No virus found in this incoming message. Checked by AVG Anti-Virus. Version: 7.0.344 / Virus Database: 267.11.13/126 - Release Date: 09/10/2005 -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.344 / Virus Database: 267.12.0/134 - Release Date: 14/10/2005 --- This SF.Net email is sponsored by: Power Architecture Resource Center: Free content, downloads, discussions, and more. http://solutions.newsforge.com/ibmarch.tmpl ___ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
Re: [Lcms-user] vgct tags
Marti wrote: lcms does currently NOT implement it because it is not on ICC spec. Alas, I'm a bit critical on such practices. Using this kind of stuff will make profiles active in the sense they are no longer a characterization of the hardware but a way to set specific configurations. You're quite right about this. vgct is not the correct approach to calibration. What should happen is that the profile should contain the desired device response in the outputResponseTag, and some separate system should calibrate the hardware to make sure it meets the expected response for a given display profile. This provides a mechanism to track device drift. Unfortunately we're stuck with software systems that expect the vgct tag to be present (Apple systems won't load the profile if the tag is missing), even though it no longer captures all the settings of a modern display system, such as the monitor controls etc., and is the wrong information to store in a profile Graeme Gill. --- This SF.Net email is sponsored by: Power Architecture Resource Center: Free content, downloads, discussions, and more. http://solutions.newsforge.com/ibmarch.tmpl ___ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
Re: [Lcms-user] vgct tags
I notice that lcms 1.15 has defined the vcgt tag (version 1.14 does not) but the documentation does not list vcgt as one of the implemented tags. So I am wondering if the documentation is correct or if version 1.15 has support for adding a vcgt tag to a profile. On Monday 10 October 2005 09:29 am, Hal V. Engel wrote: On Sunday 09 October 2005 05:46 pm, Graeme Gill wrote: Hal V. Engel wrote: I would like to setup LPROF so that it will create vgct tabs in monitor profiles. I looked at the LCMS docs and it has nothing about vgct tags there so I am not sure where to begin. Does anyone here know anything about this? If so could you point me to sources of information about this to help me get started? icclib supports vgct tags - see http://www.argyllcms.com/icclibsrc.html and look for VideoCardGamma in icc.c and *.h. Graeme Gill. Graeme, Great that helps allot. I don't really want to use two libraries to get this all working but at the present time lcms has no direct support for vcgt tags. Perhaps Marti would consider adding this support? The XCalib has a patch for lcms that allows reading the vcgt data. But does not have anything related to creating them. In anycase I think I have enough to start looking at this. Thanks, Hal --- This SF.Net email is sponsored by: Power Architecture Resource Center: Free content, downloads, discussions, and more. http://solutions.newsforge.com/ibmarch.tmpl ___ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user --- This SF.Net email is sponsored by: Power Architecture Resource Center: Free content, downloads, discussions, and more. http://solutions.newsforge.com/ibmarch.tmpl ___ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
