CompositeImage color range behavior

Posted by ctrueden on Oct 29, 2008; 5:30pm
URL: http://imagej.273.s1.nabble.com/CompositeImage-color-range-behavior-tp3694614.html

Hi,

I have noticed that CompositeImages behave rather non-intuitively in some
ways, and was wondering if the behavior I'm seeing is a bug or a feature.

1. File > Open Samples > HeLa Cells
2. Image > Adjust > Color Balance

At this point, just changing between "Red", "Green", "Blue" and "All" in the
dropdown box causes some additional autoscaling to take place, changing the
visual. It seems odd to me that just changing which color table I'm looking
at should alter the image's color scaling.

3. Select "All" from the dropdown.
4. Set button, Min -> 0, Max -> 1000, OK.

The image gets more washed out at this point, as I would expect, but
changing channels between Red, Green and Blue resets the color scale channel
by channel -- as does moving the channel slider in the image window, which
seems linked to the dropdown and I'm guessing is intended to be equivalent.

Alternately, selecting the Red channel, clicking Set, entering min -> 0, max
-> 1000, and checking "Propagate to all 3 channels", I would expect it to do
the same thing as above (choosing "All" without checking that box), but the
final visual looks different. It appears that ImageJ visibly steps across
each channel applying the settings, which get instantly overwritten because
moving between the channels invokes the autoscaling procedure.

Personally, what makes sense to me would be for toggling between channels of
the CompositeImage to never affect the visual appearance or alter the color
scaling. As things stand, it is very easy to hose up your color ranges, and
the "Propagate to all X channels" checkbox seems largely ineffective.

Thanks,
Curtis