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<p>[QUOTE=&quot;messydesk, post: 2425340, member: 1765&quot;]Huh?</p><p><br /></p><p>Yesterday, someone pointed out a technology on the PCGS forum that was used to image cultural artifacts, including coins, called Reflectance Transformation Imaging.&nbsp; The organization that does this has a demo video that shows using it to view a coin, changing the lighting characteristics <i>after</i> the picture has been taken.</p><p><br /></p><p><a href="http://culturalheritageimaging.org/What_We_Do/Fields/numismatics/" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://culturalheritageimaging.org/What_We_Do/Fields/numismatics/" rel="nofollow">Here&#039;s a short video demo.</a></p><p><br /></p><p>The issue with showing someone a picture taken using this technique is that they need special viewing software to view it, but there is viewing software available as a free download (with non-numismatic sample images). The &quot;image&quot; that is being viewed has been stripped of all shadows and highlights. Each pixel represents the actual color of the coin as seen when the light is ideally placed to see that color. The viewing software is what provides a &quot;virtual light&quot; to view the coin. In order for the light to work, the coin now has to be a 3D surface, rather than a 2D image. In addition to the color, the elevation, surface normal, and reflectivity of that point of the coin must be known. All of these are derived from the initial set of photographs that are taken of the coin. A spot that varies from really bright to really dark is highly reflective, while a spot that doesn&#039;t vary no matter how it&#039;s lit could be fine corrosion. The surface color, reflectivity, normal, along with the size, shape, color, and position of the light (not demonstrated was how to diffuse or harden the light) determines how the coin is rendered for the viewer. Pretty cool. </p><p><br /></p><p>The amount of data to transmit to someone for viewing, assuming they have the viewing software either installed on their device or available as a WebGL (or other similar technology) browser plugin would be more than for a normal image, but not by orders of magnitude. Each pixel needs, in addition to the RGB value, a z-coordinate, a 3D surface normal (x,y,z), and reflectiveness, which comes out to under 3x as much data as a plain old 2D image. It probably wouldn&#039;t be very tolerant of lossy compression, but it is still far less data than a video and gives the viewer much more flexibility. </p><p><br /></p><p>So would taking the 24 pictures (the example in the article) slow the process down so much that it would make a TrueView cost $100 per coin? Nope. Much of the time spent taking the perfect coin shot is adjusting the lighting manually and interactively until it looks best. This is no longer necessary, as the privilege (burden?) of lighting is shifted to the viewer. The photographing step, including the RTI surface generation could be fully automated. The artistic work of the photographer would be limited to setting up an ideal representative traditional image by moving the virtual light(s) around and taking a virtual photo. </p><p><br /></p><p>Will I be offering this service soon? Nope. Way too complicated for a low-volume one-man shop to set up at this point. Would I if I could? Damn straight!&nbsp; The viewer and the software that generates the special image format are free downloads.&nbsp; A rig to take the pictures would ideally have a robotic arm holding a light, with both the camera and robot controlled by the same software, tagging each photo with the lighting position.&nbsp; The series of lighting angles used would then be repeatable every time.[/QUOTE]</p><p><br /></p>

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