Semi-precise Gaussian?

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Robert Schleif
Posts: 235
Joined: May 1st, 2009, 8:28 pm

Semi-precise Gaussian?

Post by Robert Schleif »

Sometimes I want to blur a background without bleeding and with a blur radius quite a lot larger than 64 pixels (Being faster than Precise Gaussian wouldn't hurt either.). Might a transformation be developed that uses the box filter blurring method as in Gaussian Blur with a mask that functions like the Blur Mask in the Precise Gaussian?

jsachs
Posts: 3289
Joined: January 22nd, 2009, 11:03 pm

Re: Semi-precise Gaussian?

Post by jsachs »

Unfortunately you cannot use the box filter with a mask. Once you start using a mask, it is actually faster to do use a real gaussian than to make two passes with a box filter. I could increase the maximum radius, but the running time is proportional to the square of the radius.
Jonathan Sachs
Digital Light & Color

Robert Schleif
Posts: 235
Joined: May 1st, 2009, 8:28 pm

Re: Semi-precise Gaussian?

Post by Robert Schleif »

If the mask had hard edges, I've wondered about reducing the area of the image and mask a factor of 25 ( x 1/5 in each direction), performing a precise Gaussian on the resized image with the resized mask, then resizing the blurred image back to the original size, and finally using Composite with the original mask to generate the original image that is precise Gaussian blurred as specified by the mask. If this produces decently blurring results, perhaps this procedure could be an option within Precise Gaussian.

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