Posted by
Joachim Wesner on
URL: http://imagej.273.s1.nabble.com/Brightness-contrast-selection-in-grayscale-images-tp3689259p3689261.html
Hi Michael,
>With a greyscale image, the brightness/contrast adjustment provides
>the live feedback by adjusting the LUT associated the image. The LUT
>applies to the whole image and not just the ROI. However, you need
>only press the "Apply" button on the "Brightness & Contrast" palette
>for the changes to be applied to the ROI (changing the pixel values
>within the ROI). The LUT then gets reset and the pixels outside the
>ROI are thus unaltered.
Did you actually try this? This does only work for 8-bit grayscale data,
not for the probably more
interesting 16 and 32 bit cases. As fas as I can see, this is because in
the former case the
effect of the modified LUT (which itself is based on only 8 bits) can be
exactly duplicated by
rewriting the data within the ROI, having to stick with any "rounding
errors" caused by it.
However, for 16 and higher bit cases it probably should be possible to
duplicate the effect
by a more complicated calculation without loosing too much of the extra
resolution... Hmmmm!
Mit freundlichen Grüßen / Best regards
Joachim Wesner
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