Re: [Gimp-developer] Gimp from git Gegl Gaussian Blur and Unsharp Mask useability issues

On 12/03/2013 02:10 PM, Teo Mazars wrote:

The way GEGL currently exposes each numerical parameters is as follow:

1) A nominal range, say [a, b], which represents the range where the operation is expected to work
2) An UI range, [a', b'] included in [a, b], representing the area of interest of the parameter.
3) An exponent, (like a gamma correction), to make the slider not behave linearly on the [a', b'] range.

Currently, GIMP's sliders "show" only [a', b'], but allows values in [a, b]. The exponent is the way GEGL handles the 
"mutli-scale" problem and it allows to have more precision on small value. Those values are all in GEGL, look for eg 
gegl_chant_double_ui in /operations/common/*.c

I will let others comment on what is the optimal UI range for those two operations. But changing [a', b'] would be really easy, 
and it should change the "unit" as well. I am not sure about making that range "user configurable", it makes 
sense imho.

That sounds like maybe I can change the slider scale in the source code pretty easily, even if it never gets changed in git. Thanks! I'll give that a try. The slider scales have been a constant issue. I thought I would get used to them, but that never happened.

In the GEGL Gaussian blur, parameters are the std_dev along x and y, describing mathematically the Gaussian curve used 
as kernel. Though, I have to read the code to know where the infinite curve is clipped to have a 
"only-one-pixel" actual radius. Which is not obvious...

I'll have to look up what that means. Is there a simple approximate conversion to pixel radius?

Other than that, I don't really understand the "Masks" comment. You can see the actual mask by checking "Show the 
layer mask", but perhaps you want to see both the mask and the resulting image at the same time?

User error! "Show the layer mask works perfectly", exactly what I wanted right under my nose and I never noticed it. Gimp never ceases to amaze me. Thank you so much!

Hah, and the "computational explosion" with bad parameters is a known bug in a lot of GEGL operations, it may even make 
GIMP crash. It probably needs to be fixed in each operation individually, but this is not obvious... Perhaps we will need to make 
the "process" step of GeglOperations cancellable at some point? Unclear...

Good to know it's a known issue.

Also keep in mind that this is all "work in progress", Mitch once said that the ui infrastructure for GEGL 
Operations in GIMP is not done. And most of GEGL Operations still need some love.

It did seem like it might be a good time for feedback on various ui issues, yes? no?

On 12/03/2013 02:45 PM, Joao S. O. Bueno wrote:
Certainly it would be a lot better if while trying to click on the
number to type in a new valuein the Gaussian Blur filter dialog in
GIMP, you could not "accidentally" click on the bar bringnig the
radius to 850, and having to wait several seconds until GIMP becomes
responsive again.

"accidentally" is quoted, because it is actually very hard not to make
that happen. I know the widgets are pretty - no one can deny that -
but maybe, just letting the typeable values lie outside the range of
the slider would be a nice-enough fix already.

You are right to quote "accidentally"! It's really easy to have that accident happen. I have plenty of RAM, but my processors are slow and my graphics card isn't up-to-date. So those little accidents are painful and it can take considerably longer than several seconds to recover.

When I'm experimenting to find just the right value, I find it easier to make small experimental changes with a slider than with a box for typing, if the slider is set up with an appropriate range. Not to say everyone would feel that way, of course.

The flip side is that just as soon as the slider range is made smaller, one wants a larger range. I remember using some application that allowed to change the scale of a slider easily and instantly. It was very convenient.


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