Quoting Ellie Kennard: > Correct me if I am confused, here, but I fail to see how data that > has not been present on image capture (scan or digital photo) can be > created by Photoshop on opening. If I scan at 8 bits, the file is > half the size of a file scanned at 16 bits. The information is just > not there to convert into 16 bit. Perhaps there is something I don't > know about here?
Ellie/Jonathan: While working in 16 bit will provide "smoother" transitions between tonal areas, the real difference you are seeing is due to a wee bit of dithering that is added when you make the trip from 16 bit to 8 bit. Try this experiment. Open an 8-bit jpeg duplicate the image. Take the duplicated image and convert to 16 bit. Perform the global adjustments (curves, levels, hue/saturation, etc), using the "command/control" key to make sure the same edits are done on both (if using CS, you may be able to perform each as adjustment layers and drag them to the other image). Take the 16 bit image and convert back to 8 bit. Now take the 8 bit version, and convert to 16 bit. Then do a second conversion (not an UNDO) from 16 bit to 8 bit. Compare both visually on screen, as well as the histogram. I'll be surprised if you see much if any difference at all on screen or in the histogram, and if you print both, I'll bet you see no difference whatsoever. Hope that helps. David -- Creating an image database? visit (http://ControlledVocabulary.com/) and join the discussion list, or read areview of the Image Info Toolkit utility at: (http://ControlledVocabulary.com/imagedatabases/imageinfotoolkit.html) David Riecks http://www.riecks.com - http://zillionbucks.com =============================================================== GO TO http://www.prodig.org for ~ GUIDELINES ~ un/SUBSCRIBING ~ ITEMS for SALE
