Accurate colour iamges: from expensive luxury to essential resource

摘要

Over ten years ago the National Gallery in London began a programme to make digital images of paintings in the collection using a colorimetric imaging system. This was to provide a permanent record of the state of paintings against which future iamges could be compared to determine if any changes had occurred. It quickly became apparent that such iamges could be used not only for scientific purposes, but also in applications where transparencies were then being used, for example as source materials for printed books and catalogues or for computer-based information systems. During the 1990s we were involved in the development of a series of digital cameras that have combined the high colour accuracy of the roiginal 'scientific' imaging system with the familiarity and portability of a medium format camera. This has culminated in the programme of digitization now in progress at the National Gallery. By the middle of 2001 we will have digitized all the major paintings in the collection at a resolution of 10,000 pixels along their longest dimension and with calibrated colour; we are on target to digitize the whole collection by the end of 2002. The images are available on-line within the museum for consultation and so that Gallery departments can used the images in printed publications and on the Gallery's web-site. We describe the development of the imaging sysems used at National Gallery and how the research we have conducted into high-resolution accurate colour imaging has developed from being a peripheral, if harmless, research activity to becoming a central part of the Gallery's information and publication strategy. Finally, we discuss some outstanding issues, such as interfacing our colour management procedures with the systems used by external organisations.