On 10/19/07, Greg Troxel <[EMAIL PROTECTED]> wrote: > [EMAIL PROTECTED] writes: > > > But that's all you need for a digital camera. They are very simple > > devices -- three colour filters and a linear CCD. Your profile > > accuracy is limited by the physics of the filters: how close are they > > to XYZ? They are the exact (almost) complement to a CRT. If you're > > calibrating your CRT all you need is a 3x3 matrix and three LUTs. > > So you're saying that the linearity of the camera (once you take out > black point) is so good that it's reasonable to just computate a matrix, > rather than also having a linearity correction curve. I looked at a > profile of my old notebook's LCD that was created with an Eye-One > spectrophotomer, and it was definitely non-linear. But it does seems > that everyone assumes the cameras are linear.
An LCD will be rather non-linear, and a CRT certainly is (it follows a power law). But the CCD in a camera is absolutely linear. If you do see non-linearities, in my experience they come from either internal camera firmware processing (hopefully you can turn this off, or look up exactly what the firmware is doing in the docs) or from scatter in the optics. IMO you don't want to include either of these in your profile. John ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
