Posted by
Michael Ellis on
URL: http://imagej.273.s1.nabble.com/Brightness-contrast-selection-in-grayscale-images-tp3689259p3689260.html
Neil,
I *think* this is the reason:
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.
Since RGB images have no LUT, the interactive adjustment of brightness
and contrast for RGB images is done by direct manipulation of the
pixel data and this is done only to those pixels that lie within the
ROI.
In short, adjust the brightness and contrast to taste, then click on
"Apply" and only the portion of the image in the ROI will be changed.
Michael Ellis
On 21 Feb 2010, at 14:11, ph73nt wrote:
> Hi list
>
> I am struggling to set the brightness and contrast within a
> selection of an
> image. This works fine for 24-bit RGB images, but when attempting
> this on
> grey-scale images the whole image is windowed, rather than my
> selection. It
> is possible to work around this by switching types, but it is
> inelegant and
> not much good when working with floats.
>
> Is there a particular reason for this? Does anyone know of a trivial
> solution?
>
> Many thanks, Neil
> --
> View this message in context:
http://n2.nabble.com/Brightness-contrast-selection-in-grayscale-images-tp4606825p4606825.html> Sent from the ImageJ mailing list archive at Nabble.com.
Michael Ellis
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