A system is being developed to allow WWW browsing of very high resolution (up to 20,000 by 20,000 pixels), colorimetric images. These come from the new generation of image acquisition systems in art galleries — the images are equivalent in resolution to a large-format transparency, but have accurate and consistent colour. Because colour is consistent, images from different sites may be compared on screen: differences in appearance between the images are guaranteed to be due to real differences between the objects, a very valuable property for art and conservation applications. The images are held as tiled pyramidal JPEG TIFF file at a server, and are transmitted via standard HTTP requests to a Java client. Only the portions of the image needed are requested and transmitted. The research is part of the Euro-Canadian Viseum project on making secure image archive access to museums. It has set up an ATM network from Vancouver to Berlin, Paris (the Louvre) and London (The National Gallery).