Quote:
Originally Posted by nldunne
I made a Capital "E" and gave it a color level of 127 mid grey (half way between 000 and 255 in the color scale in red, blue and green). Then I went all over my Negative Work Copy Image to find a 127 Grey point in it. Then I Tweaked my image to that Value in Hue Saturation and Sharpness Tools.
My Subject is a test case using the 127 mid grey values on a real life image.
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This may seem a bit picky but 127 isn't exactly mid grey. In fact you cannot
obtain exact mid grey in an 8 bit image. For many purposes 127 or 128 is near enough for practical purposes, but there are situations where it is necessary for it to be exact. This is why a16 bit image does not use all of the available levels; in fact, it just uses the full 15 bits plus one single level from the 16th bit. Instead of covering 65536 levels it only covers 32769 (32768 + 1). This enormous loss is acceptable because 32769 is still way beyond what can be distinguished visually. You couldn't really do the same with a 8 bit because the full 256 levels are only just enough to see a full range of visible colours;129 would be hopelessly short.
GHK