[filmscanners] Re: 8bits vs. 16bits/channel: cantheeyeseethedifference

["Anthony O'Halloran" <anthony@ohalloran.co.uk>]

>> This sounds like in going from 48 bit color to 24 bit color, you're
>> losing spatial resolution. I never realized that before.
>
>Why do you believe you are losing spatial resolution?  If you have an image
>that is 2k x 3k 16 bits/channel and convert it to a 2k x 3k 8 bits/channel
>image, you still have the same spatial resolution, 2k x 3k.  You've reduced
>the TONAL resolution, but not the spatial resolution



Spaital information and tonal information are basically equivalent to each
other. If you change a  16bit image to 8bit, you can just use two pixels to
represent the old one and you do not lose any information. Is my statement
true, yes or no?

Well yes and no. All information will be preserved we CAN NOT SEE IT!!!.



Take the example of changing a 2bit to a 1bit image.



In the 2bit image there are 4 shades of grey covering 4 pixels: 0,1,2,3



We can exactly represent this By using 1bit color and 8 pixels:0,0, 0,1,
1,0, 1,1 (This is basically halftoning). The pixels would need to be
rectangular shape in this case to keep the proportions of the image the
same.



We perceive 0,1 and 1,0 to look the same though, even though the pixel set
0,1 represents colour level 1 in the 2bit image and 1,0 represents  color
level 2 in the 2bit image. This is where loss of information occurs.



It's is like throwing 2 dice and giving your friend the total. He can't say
exactly what the 2 original numbers were but he can have a fair guess.



Anthony



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