Aperture pixel value Q

[LondonM]

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When I inspect RAW images with the loupe or pointer, the RBG values are 0-255 per channel. Shouldn't they be the bit depth of the M9 that I am using ? Or is this some bizzare colour space thing I'm not getting ?

[adan]

The readouts in most image processing programs still use the number scale for 8-bit images. Partly because people are used to them (off the top of your head, how "bright" or "dark" is 22,475? How "red" is 59678/21347/9015? Most people already know how "bright" 102 or 214 are on the 0-255 scale.)

 

Additionally, the histograms do have to fit on a computer monitor. A histogram graphing all the discrete values (a one-pixel-wide column for each value) from 0 to 63,999 in a 16-bit image would be 640 inches wide (53 feet/16.4 meters) at 100 ppi screen resolution - or cover about 33 HDTV (1080p) monitors side by side.

 

The program will actually use all 63,999 values (or whatever corresponds to the bit depth of a given camera) when processing the image - displaying them in the user interface amounts to information overload.

[LondonM]

Thanks. It's 14 bit, so the range should be 0-16,383.

 

I do like the full scale as a learning tool. It helps me see what happens to dynamic range when I play with different processing options. I realize all monitors and printers don't have this kind of dynamic range, so it's just a learning tool for me. I deal with MRI images for a living and all the processing is done as 16 or 32 bit. So I'm used to interpreting those numbers. If I was a traditional RGB guy, yes I can see 0-255 being more easy to interpret.