Strange behaviour of brightness/contrast settings

[Jochen Reichel]

Hello,

I want to report a strange behaviour of the brightness/contrast (B/C)
settings when dealing with different image types (16-bit vs. RGB).
I am currently working with imageJ 1.50c4 (daily build from just now).

1) If I work on a 16-bit image, everything works fine: I can adjust the
B/C by moving the sliders in the dedicated B/C window (without pressing
"Apply"!), click into the image, move around in the zoomed image, and
adjust the B/C level differently again just for viewing purposes. The
underlying intensity data of the pixels are never altered (only the
representation on the monitor is) unless I click the "Apply" button.
This is the behaviour I would expect.

2) If I work on a RGB image this is different. When I adjust the
B/C-level (without pressing "Apply") and then just click into the image,
the B/C settings are automatically applied! This is not what I want,
because sometimes I need to move around in the zoomed image and adjust
the B/C level differently for different areas of the sample (only for
viewing purposes). This does not work because more and more information
gets lost by this automatic application of the B/C level.

Is this a bug or a feature? ;)

Regards,
Jochen Reichel

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[Rasband, Wayne (NIH/NIMH) [E]]

> On Sep 8, 2015, at 4:36 AM, Jochen Reichel <[hidden email]> wrote:
>
> Hello,
>
> I want to report a strange behaviour of the brightness/contrast (B/C) settings when dealing with different image types (16-bit vs. RGB).
> I am currently working with imageJ 1.50c4 (daily build from just now).
>
> 1) If I work on a 16-bit image, everything works fine: I can adjust the B/C by moving the sliders in the dedicated B/C window (without pressing "Apply"!), click into the image, move around in the zoomed image, and adjust the B/C level differently again just for viewing purposes. The underlying intensity data of the pixels are never altered (only the representation on the monitor is) unless I click the "Apply" button. This is the behaviour I would expect.
>
> 2) If I work on a RGB image this is different. When I adjust the B/C-level (without pressing "Apply") and then just click into the image, the B/C settings are automatically applied! This is not what I want, because sometimes I need to move around in the zoomed image and adjust the B/C level differently for different areas of the sample (only for viewing purposes). This does not work because more and more information gets lost by this automatic application of the B/C level.

The latest ImageJ daily build (1.50c6) fixes several bugs in the B&C dialog related to the way it works with RGB images.

-wayne

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