Re: [Gimp-user] why no difference of gaussians on layer masks? gimp 2.7.5

[Alexandre Prokoudine <alexandre prokoudine gmail com>]

On Fri, Jan 20, 2012 at 11:02 PM, Gary Aitken wrote:
> Hello all,
>
> gimp 2.7.5 on winXP, unfortunately.  New hardware problems on my freebsd
> system.  grr.  Anyway...
>
> Why won't the gimp allow me to use a difference of gaussians on a layer
> mask?  This seems like a perfectly fine thing to do for edge detection, and
> indeed, other edge-detect algorithms work:
>
> For example:
>  New layer mask, from grayscale copy of layer
>  Filters / edge-detect / difference of gaussians says:
>    Execution error for 'Difference of Gaussians':
>    Can operate on layers only (but was called on channel or mask).
> but
>  Filters / edge-detect / Edge...
>    works fine
>
> Is this a bug, or am I missing something?
> Any insights would be appreciated,

Hi Gary,

Not sure about the technical side of this, but you should be able to
perfectly work around that.

1. Enable display of the mask via right-click menu so that the mask is
displayed instead of the layers's contents.
2. Layers > New from Visible.
3. Apply your filter to that layer.
4. Copy all of the layer's contents and paste it into the mask.
5. Remove or disable the extra layer you created.

Alexandre Prokoudine
http://libregraphicsworld.org