Hi, first of all thank you both for the quick and informative answers. It is clear, that I get the best results with individual profiles for every illuminant, but I fear, I have to deal with the common behavior of the people working with microscopes and CCD-cameras doing this "white balance" on the illuminant. I got to find the best realizable solution and accept the lower precission. It will still be a great enhancement of the color quality! I think, we will try Marti's "quick and dirty"-solution, but how do I estimate the value for the TempSrc in �K? What I have are RGB-values, which are normally not equal. They should be my input white point, which I want to be mapped to R=G=B at the end. Additionally I can't be sure, that they lie exactly on the line of temperature dependent white points (I do not know, how this line is called). And what are my TempDest-values, how can I calculate them?
Regards Dirk Str�ker > Hi, > > I fully agree the good solution is to have a different profile for each > illuminant, > as that would be the *only* way to get decent results. > > However, there is a quick hack to do if you really don't care about > precission. > Again, Hal has suggested what is the "good" way, and what I am here stating > is > just quick and dirty, but anyway here we go: > > There is a specialized, virtual device link profile for doing some specific > tweaks. > One of those tweaks is white point translation. > > cmsCreateBCHSWabstractProfile(int nLUTPoints, > double Bright, > double Contrast, > double Hue, > double Saturation, > int TempSrc, > int TempDest); > > Keep Bright, Hue and Saturation to zero. Keep Contrast to 1, and set > TempSrc and TempDest > as the temperatures in �K of input and output white points. That function > would give you > a abstract devicelink handle. Do a multiprofile transform joining input > (microscope) profile, that one > and finally sRGB (or whatever output). > > Regards, > Marti Maria. > > ----- Original Message ----- > From: "Hal V Engel" <[EMAIL PROTECTED]> > To: <[email protected]> > Sent: Tuesday, March 01, 2005 2:23 AM > Subject: Re: [Lcms-user] White balance > > Dirk, > > As you have found out when doing color profiles for a device everything in > the color processing chain matters and has an impact on the resulting > profile. A different light source or a light source adjusted differently > will change the profile. As a photographer I do not expect my day light > camera profiles to work with photos that were shot using tungsten light. > So I have profiles for my camera for each type of light that I might shot > with as well as for each film type. On some occasions I may shot a custom > color target for a specific shoot because I am not sure of the lighting. > So there is no easy answer as you can not reasonably expect a profile that > is created using one device to work perfectly for another similar device. > Let alone for > a similar device with the light adjusted differently. > > This all boils down to having a consistant workflow so that you can > reproduce > the same results consistently. Since my situation is such that I only > have to deal with my personal workflow this is not a big issue. I > understand how important this is and I always follow a consistant routine > so that my results > are reproducible. It sounds like you are dealing with others that may need > training to understand how this works and how their workflow influences the > results they get. In addition it may require that you have a number of > profiles that are correct for different devices and conditions. > > Hal > > On Monday 28 February 2005 01:22 pm, Dirk Str�ker wrote: > > Am Montag, 28. Februar 2005 22:18 schrieb Dirk Str�ker: > > > Hi everybody, > > > > > > I have a problem, which might is simple to solve, but in the moment > > > I'm a bit confused and can't find a simple answer. > > > Before I explain my problem I will give a short description of my > > > setup. I'm working with a CCD-camera on a microscope. The color quality > > > of the system was very bad, so I did some research, found ICC-profiles, > > > color management...and so on (I learned a lot in the past weeks ;-) > > > ). We bought software from Gretag MacBeth to create profiles for the > > > cameras > > > and we were pretty impressed over the results. After that we found > > > "littleCMS" and tried to use it to achieve the improved color quality > > > directly, which worked fine. > > > The problem is, that it is a common technique, to make a so called > > > "white > > > balance" on the "illumination", the yellowish ligth of the tungsten > > > halogen lamp should be white or gray (R=G=B). I understood the ICC > > > color-management-technique in that way, that this is normally done by > > > the > > > chromatic adaption tag (often the "Bradford matrix"). This is matrix is > > > calculated while creating the profile. > > > But not every individual microscope lamp is the same. Some people dim > > > the > > > lamp, or the lamp is older... but everyone wants to make the pure lamp > > > light gray. > > > How can I do this > > > > Oops, I wasn't ready. > > > > Should I use "cmsCreateRGBProfile" and make a "transform" with the > > "normal" > > camera profile + the new RGBProfile? > > > > Maybe there is a simple solution and I'm just to blind to see... > > > > I hope my explanations weren't to confusing ;-) > > > > > > > > Dirk Str�ker > > > > > > ------------------------------------------------------- > > SF email is sponsored by - The IT Product Guide > > Read honest & candid reviews on hundreds of IT Products from real users. > > Discover which products truly live up to the hype. Start reading now. > > http://ads.osdn.com/?ad_ide95&alloc_id396&op�k > > _______________________________________________ > > Lcms-user mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/lcms-user ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_ide95&alloc_id396&op=click _______________________________________________ Lcms-user mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/lcms-user
