Hi Simon,
in ImageJ the minimum and maximum displayed brightness do not
necessarily correspond to the minimum and maximum value that you can
have with a given data type (0-255 for 8 bit, 0-65535 for 16 bit).
You can modify the values that are mapped onto white and black by
ImageProcessor.setMinAndMax (in a plugin) or simply by
Image>Adjust>Brightness and Contrast (interactively).
You can get the min&max values by ImageProcessor.getMin(),
ImageProcessor.getMax().
In Edit>Options>Conversions there is a checkbox for whether
conversion of the image data from 16 bit to 8 bit uses the displayed
grayscale range or all of 0-65535 for the final 0-255. If you do this
in a plugin there is a boolean in the type conversion that does the
same.
Michael
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On 2 Feb 2010, at 09:53, Simon Andrews wrote:
> I'm writing a plugin which creates a derived RGB image from a 16
> bit greyscale image input. However I'm having trouble getting the
> scaling of the image intensity the same as is shown when ImageJ
> initially renders the 16 bit image.
>
> It seems that for display purposes ImageJ alters the brightness
> scaling of 16 bit images. I see pixel values of ~200 which are
> clearly visible, but if I scale these down to the equivalent 8-bit
> values then they would be so close to zero as to be effectively black.
>
> How can I convert the values returned by getIntensity() to
> something from which I can infer the actual brightness shown on
> screen when the 16 bit image is displayed?
>
> Thanks for any help
>
> Simon.
Locked
