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Re: changing contrast and brightness on the fly

When you see how the end-users operate, having the slider-less control makes
good sense.  The images are not being displayed for quantitation but for
"expert review" by a radiologist who does all the feature recognition, often
rather rapidly.  They want to be able to stare at the image and change the
contrast and brightness without looking away from the image, which is when
slider controls get to be irritating.  So, the existing software is, for its
purpose, very satisfactory indeed.

The only other approach I'd thought of was going back to the (good old?) days
of Evans and Sutherland-type terminal with actual physical dials you could
turn while looking at the screen - very nice for independent x/y/z rotation
of 3D stuff.  But we don't want to turn this into a hardware problem ...



Mark Hadfield wrote:

> From: "Simon Williams" <williams.simon@gene.com>
> > The job is to display one or more grayscale MRI images (mostly small,
> > 256 pixels squared is common) and then to be able to adjust the image
> > brightness and contrast interactively, without going to any special
> > widgets like sliders. The functionality I have in mind is to
> > middle-click the image and then have drag right/left control contrast
> > and drag up/down control brightness.
> >
> > The plan is to replicate functionality that the end users (radiology
> > folks) are already familiar with from other image viewers.
> Well, if that's what the users demand, then I guess you have to give it to
> them. Me, I think sliders would be preferable, because they provide a
> readout of the current setting. Don't duplicate the unsatisfactory aspects
> of the existing software unless it's really necessary!
> Have you noticed what TV remote controls do when you adjust the volume etc
> these days? They pop up an on-screen slider! Mind you, I'm not suggesting
> you try to code up an on-screen slider in IDL (though I'm sure David would
> love to give it ago). Sliders at the bottom of each image would work just
> fine.
> ---
> Mark Hadfield
> m.hadfield@niwa.cri.nz  http://katipo.niwa.cri.nz/~hadfield
> National Institute for Water and Atmospheric Research
> --
> Posted from clam.niwa.cri.nz []
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