roamingstudio Posted January 7, 2006 Share Posted January 7, 2006 Ok im sure this is addressed elsewhere - but a search for '16 bit cs2' did not help. In martin evening's book on photoshop he regularly states it is actually only using 15 bits per channel - but so far I have not seen why this is the case. Does anyone know the technical reason behind this? Does CS2 use a structure like struct{ signed short Red, signed short Blue, signed short Green} Pixel;? Having programmed 16 bit image processing algorithms for machine vision I find the short coming a little strange. Thanks in advance, Marc Link to comment Share on other sites More sharing options...
basscheffers Posted January 7, 2006 Share Posted January 7, 2006 Considering that most source material is 8 or 12 bit at the most, I wouldn't fret over wether it is true 16 bit or really just 15 bit and letting one go to waste. Link to comment Share on other sites More sharing options...
jakob_norstedt_moberg Posted January 7, 2006 Share Posted January 7, 2006 CS2 supports HDR (32bit float) so the question is relevant. Jakob Link to comment Share on other sites More sharing options...
andrew_rodney1 Posted January 7, 2006 Share Posted January 7, 2006 The high-bit representation in Photoshop has always been "15 1" bits (32767 (which is the total number of values that can be represented by 15 bits of precision) 1). This requires 16 bits of data to represent is called "16 bit". It is not an arbitrary decision on how to display this data, it is displaying an exact representation of the exact data Photoshop is using, just as 0-255 is displayed for 8 bit files. Andrew Rodneyhttp://www.digitaldog.net/ Link to comment Share on other sites More sharing options...
roamingstudio Posted January 8, 2006 Author Share Posted January 8, 2006 So in other words when you take the raw format and convert it into a picture the maximum number which can be generated for any one colour channel is <32768? (ie 15 bit). That would imply therefore that most of the CCD sensors are not reporting true 16 bit per colour (12 bit?). Does anyone know the exact sampling range of the new CCD's / colour (e.g. for EOS 20D, EOS 5D). I suspect it is written on a website somewhere.... Im not too worried (or bothered) - it was more an anomoly which did not seem to be well documented. Link to comment Share on other sites More sharing options...
kelly_flanigan1 Posted January 8, 2006 Share Posted January 8, 2006 Once 1 bit was the cost of a gallon of gasoline, the old Eclipse Rocket was a mightly 1.8HP, with oak rollers. We worried about the bomb. Link to comment Share on other sites More sharing options...
roamingstudio Posted January 9, 2006 Author Share Posted January 9, 2006 And I worried about programming my ZX81 each day. Sigh. ;-) Link to comment Share on other sites More sharing options...
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