CIFilter blur issues

[Paul Sargent]

On 18 Dec 2007, at 08:18, mikevann wrote:

> I'm doing a gaussian blur using Core Image (CIGaussianBlur).  The  
> problem I'm having is the edges are not being extended during the  
> blur so all four edges fade into transparency.  Is there a way to  
> control how the CIGaussianBlur treats edges, such as  
> kvImageEdgeExtend does for vImage convolves, or at least set the  
> background color used for the blur?

I don't think so, as the edge behaviour is a property of the sampler.  
The code to create the sampler is inside the CIFilter, hence it is  
only modifiable if you write a custom filter. (That doesn't stop  
Quartz Composer doing it, so there's a method somewhere, but I don't  
think it's public)

The only solution I've come up with (in theory) is to have another  
filter add a clamped edge to the image prior to blurring.