Zoom Blur

[siuying]

The very center isn't blured. but that is only a single pixel.

If you want to make the area near the center less blurred you will need to create a blur map of some kind.

Thank you for your input!

I tried to modified the gradient brightness:

Code: Select all

	MagickWand* tWand = NewMagickWand();
	MagickSetOption(tWand, "compose:args", "5");
	MagickSetSize(tWand, w, h);
	MagickReadImage(tWand, "radial-gradient:black-white");
	MagickBrightnessContrastImage(tWand, -50.0, 0.0);
	MagickCompositeImage(self.wand, tWand, BlurCompositeOp, 0, 0);
	DestroyMagickWand(tWand);

The created map:


The applied result:


The center area should be #000000 already, but for some reason some blur is still applied?

[fmw42]

radial-gradient has a straight line profile, so it is only zero at the very center and goes linearly out from there to full white. in stead of using brightness-contrast (or perhaps in addition) you probably want to use -black-threshold so that all values below some percent (or value) go exactly to black. That will make a center circle that will be exactly black

[anthony]

Their is currently a minimum of a 0.5 pixel sized blur in the way the blur map is applied.
This is caused by minimum support limits in Elliptical filter that is applied.

I have made some modifications to the filter handling that will let me fix this problem, but have not gotten around to it.
And with all the Christmas activities going on I am not certain when I will get around to fixing it.
It is however on my ToDo list.

[siuying]

Their is currently a minimum of a 0.5 pixel sized blur in the way the blur map is applied.
This is caused by minimum support limits in Elliptical filter that is applied.

I have made some modifications to the filter handling that will let me fix this problem, but have not gotten around to it.
And with all the Christmas activities going on I am not certain when I will get around to fixing it.
It is however on my ToDo list.

Thank you very much! Good to know this could be fixed. Merry Christmas!!

[anthony]

Except the fix I finally did apply proved to cause IM to be far too slow, so was removed again.

I really need to try something else.