Hello everyone I have two questions that I am sure the list will be able to answer with out breaking a sweat.
Firstly I'm currently doing a little bit work on digital camera characterisation and I need to capture an image of a IT-8 chart. I have had trouble getting PERFECTLY even illumination across the entire chart with out any hint of specular reflections. The most common arrangement is to have two lights angled at 45� over the chart with the camera in between (a basic copy stand arrangement). Any suggestions or improvements. Secondly I have a very technical question (Neil this might be right down your ally). It is about camera white balancing and white point conversion. Say for example I capture an image of the IT-8 chart using flash (please ignore that I mentioned tungsten lights earlier) that has a colour temperature of 4400 K , hence I set the cameras white balance to flash. Is it correct to think that the white point of the image corresponds to 4400K or X-0.979, Y-1.0 and Z-0.97??? I assume it does, am I wrong?? The reason why I ask is because after calculating the colour patches XYZ values (using just a little bit of maths) I use the chromatic adaptation transform to convert the white point of the image colour patches from 4400k to 6500k(D65) using the above mentioned XYZ (0.97, 1, 0.69) values as starting data ( this is so I can calculate the colour difference of each patch in the image to that of the original). Does the cameras white balancing change the white point of the image away from 4400k hence making my white point conversion wrong?
