Hi Bob / Hal. Thanks for your replies - they are appreciated.
The output devices I listed were just examples of what could be used but in reality our customers could be using any digital press. As Bob suggested I think our best approach might be to select the colour space that best represents the original images and convert them to that. The tricky thing is that we will also not have any control over the source images so in theory they could have any profile attached. I've been doing some tests with pictures from different cameras that I have access to and using the wide gamut rgb profile (obviously) seems to result in the least number of lost colours. Do you think that converting to this sort of profile and embedding it within the output file will be the best solution? Regards, Kevin. ________________________________________ From: Bob Friesenhahn [EMAIL PROTECTED] Sent: 07 June 2008 18:31 To: Kevin Gale Cc: lcms-user@lists.sourceforge.net Subject: Re: [Lcms-user] Compositing Camera Pictures Query - Help Required On Sat, 7 Jun 2008, Kevin Gale wrote: > > I need to composite several JPEG / TIFF digital camera pictures that > use different profiles (Adobe RGB, Camera RGB Profile etc..) into a > single bitmap. I would appreciate it if someone could help answer > the following questions: > 1. Should I just convert the images to a single profile such as sRGB? Does sRGB support all the colors you are interested in? > 2. The composited picture will eventually be printed to a digital > press such as a Canon ImagePress C1 or an HP Indigo. Should I > include the sRGB profile in my output JPEG or should I just save the > image without a profile? In order to preserve as much of the original as possible in the final output, perhaps it makes sense to convert your images to a colorspace which is as close to what these devices support as possible prior to composition. This approach prioritizes the quality of the printed output and may reduce artifacts such as banding. Another alternative is to chose a larger colorspace which best represents the colors in your images so that there is minimum original color loss and then your composited image is in that colorspace (with attached profile). This second approach prioritizes the quality of the composited master image over the quality of the device-specific image. Best quality composition may have completely different requirements depending on the type of composition used. There are those (particularly those in the compositing business) who will express the opinion that composition should only be done in a linear-light space (gamma "correction" removed). Camera RAW images are usually in linear-light space since that is what the sensors detect whereas camera JPEG images are usually white-point adjusted and gamma encoded to minimize loss with 8 bit storage, and to be more similar to sRGB. Bob ====================================== Bob Friesenhahn [EMAIL PROTECTED], http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://sourceforge.net/services/buy/index.php _______________________________________________ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
