On Fri, 10 Jan 2003 09:42:47 +0100 Thomas Holm / Pixl wrote - Subject: Re: [PRODIG] Testing the GretagMacbeth Color Card (LONG!) Jorge Parra wrote: > Hence my plan to look for a systematic approach to color control, which , > IMHO, should be easy to standardise if the set conditions don't change.
But they do. Reproducing art is a VERY large subject and I bet one of the best people to help in this particular area is Tony Riley, who took a real scientific approach to the subject. Speak up Tony (the kendal one), you'r the resident expert here. Hi Thomas Thank you for the compliment, but I don't feel expert compared to a lot of listees. The more I look into it, the less I feel I know. I don't have Jorge's original query, since I only save occasional list postings, and skim through a lot when I'm busy. It's true my (undergraduate, not PhD) topic is the digital reproduction of paintings, but I'm having problems with it. No one at the university understands colour science or colour management, and my supervisor turned down my idea (altering the col temp to avoid camera gain in blue). Frustrating because the topic fascinates me. Rather than write a long posting, let me refer anyone interested to the best reference I found - http://www.cis.rit.edu/research/mcsl/research/PDFs/Berns_art_digitize_lowres .pdf This is a report by a major Munsell Color Science Laboratory scientist, Dr Roy Berns, who spent a year at the National Gallery of Art in Washington as Senior Fellow in Conservation Science. It includes a scientific comparison of colour accuracy between a line scan camera back, a 2D CCD area array camera, scanned 10x8 film copy and a specialised IBM camera with the CCD response built to match the human visual system's response. Another scientist there has also produced the standard work on colour appearance models (Mark Fairchild). And their MSc course plods through Hunt's classic Reproduction of Colour chapter by chapter (new edition just out, cheap for a colour science book at �75!). I wish! I ask myself, if colour accuracy is quantifiable, why don't camera manufacturer's ever say how colour accurate their cameras are? Photograph a standard target in standard lighting and do the numbers. This is tongue in cheek a bit, I actually have a lot of respect for the designers of this amazing technology. I'll look in the archive for Jorge's posting. I'm actually finding that 'the set conditions not changing' is quite difficult to achieve. Considering the lighting - how much does the colour temperature change during the CCD acquisition phase (how much does the voltage vary?). How repeatable is it? Tony =============================================================== GO TO http://www.prodig.org for ~ GUIDELINES ~ un/SUBSCRIBING ~ ITEMS for SALE
