Archived posting to the Leica Users Group, 2009/06/04
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Digital use sharpening in the following three cases - two of them "required", one discretionary. 1 - Capture Sharpening: At the time of capture, each pixel is a discrete distance from its neighbors. Anti-aliasing techniques, whether physical or using software, are required to avoid the generation of artifacts like moire patterns. The interpolation required by the capture process causes the dark side of each edge to get lighter, and the light side to get darker. Sharpening compensates for for this effect. 2- Creative sharpening: Never required, but occasionally useful. Analogous to rubbing on the print or breathing heavily on a local area to increase local contrast 3- Output sharpening: To compensate for the blurring of edges induced both by another round of digitization and the randomness of the of the blobs of ink as they leave the print head and spray onto the paper. The process darkens the dark side and brightens the bright side of each edge to offset the opposite direction lightening and darkening effect of the printing process. Future generations will marvel at the "requirement" that analog techniques have that one has to remove the sensor from the camera and run it through several processing stages involving smelly liquids before seeing an image. "Why not simply lift the image off the sensor in the camera" they will say. In the long run, I suspect that digital deconvolving techniques will improve to allowing increasing depth of field to compensate for serious focusing errors - and probably be built into the camera or raw converter. -- Clive Blog: http://clive.moss.net/blog Photographs: http://clive.smugmug.com On Thu, Jun 4, 2009 at 7:59 AM, Frank Filippone <red735i at earthlink.net>wrote: > ... > What I do not understand is why digital "requires" sharpening, when for the > past 150 or so years, film did not. > > Or was it that film did not have this facility ( other than some pretty > obscure and relatively rarely used masking techniques) and digitally, the > facility is only a mouse click away? > ...