Hi Julie,
ImageJ uses the Java convention for HSB. As far as I remember, the 'Brightness' is simply the max of the RGB values, so it's a 'HSV' model according to the Wikipedia article.
https://en.wikipedia.org/wiki/HSL_and_HSVAll values are scaled 0...255 to fit 8-bit numbers, so the Hue is not 0...360 degrees as it is often defined.
Michael
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On Jan 21, 2016, at 22:09, Julie Colpitts wrote:
> Hi there,
> I am looking to measure the hue, saturation and brightness of manually
> selected areas on RGB images. I have been playing with images of known
> colour in order to verify that any output from ImageJ matches my
> expectations. After converting the image to an RBG stack, the 'mean gray
> value' of each slice corresponds to my expected red, green and blue values.
> However, when I follow the same procedure after converting to an HSB stack,
> the values do not correspond with my expected hue, saturation and brightness
> values.
> What I am wondering is if there is an unusual scale that any or all of the
> hue, saturation and brightness values are measured on in ImageJ (or if the
> mean gray value of each of these stacks is actually a viable way to measure
> HSB), and if there is a simple, straightforward way to measure the mean of
> each of those values for a selected area on an image.
> Any insight is greatly appreciated.
> Thank you very much,
> JC
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