Re: [Gimp-user] Applying large blur only to selection

2009-06-02 Thread Sven Neumann
Hi,

On Mon, 2009-06-01 at 14:12 -0500, Leonard Evens wrote:

> 
> Of course you are right.  My problem was that I copied the selection
> into a new layer with transparency as the fill type.   I don't really
> understand what happened, but it appears the transparency was being
> averaged, so after the gaussian blur, the selection in the new layer
> appeared to fade out at the edges, thus looking "lighter".

This is the expected behavior. You can lock the alpha channel in the
Layers dialog if you don't want that to happen.


Sven


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Re: [Gimp-user] Applying large blur only to selection

2009-06-01 Thread Leonard Evens
On Mon, 2009-06-01 at 19:25 +0200, Sven Neumann wrote:
> Hi,
> 
> On Sun, 2009-05-31 at 08:12 -0500, Leonard Evens wrote:
>  
> > > Copy your selection, paste it to a new layer and blur that layer. Does
> > > that give the desired result?
> > 
> > I don't believe so.   I tried it.   It still used pixels outside the
> > selection in computing the new pixel values in the desired region.  In
> > this case, those values were zero, so that lightened the region at the
> > edges.
> 
> Zeros would not lighten the edges, but darken them. What Blur did you
> use at all?

Of course you are right.  My problem was that I copied the selection
into a new layer with transparency as the fill type.   I don't really
understand what happened, but it appears the transparency was being
averaged, so after the gaussian blur, the selection in the new layer
appeared to fade out at the edges, thus looking "lighter".  I don't use
transparency controls much, so I will have to reeducate myself in the
subject to understand what happened.   

I've tried it again, using white as the fill type.  This time the
selection got whiter near the edges.  That is not what I want.

Maybe there is some way to do this to get it right, but as of yet I
don't know what  it might be.
> 
> 
> Sven
> 
-- 
Leonard Evens 
Mathematics Department, Northwestern University

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Re: [Gimp-user] Applying large blur only to selection

2009-06-01 Thread Sven Neumann
Hi,

On Sun, 2009-05-31 at 08:12 -0500, Leonard Evens wrote:
 
> > Copy your selection, paste it to a new layer and blur that layer. Does
> > that give the desired result?
> 
> I don't believe so.   I tried it.   It still used pixels outside the
> selection in computing the new pixel values in the desired region.  In
> this case, those values were zero, so that lightened the region at the
> edges.

Zeros would not lighten the edges, but darken them. What Blur did you
use at all?


Sven


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Re: [Gimp-user] Applying large blur only to selection

2009-05-31 Thread Olivier Lecarme
Leonard Evens  wrote:

> On Sun, 2009-05-31 at 08:39 +0200, Sven Neumann wrote:
> > Hi,
> > 
> > On Sat, 2009-05-30 at 21:24 -0500, Leonard Evens wrote:
> > > I want to blur the sky so that only pixels in the selection are used in
> > > computing the new values.  Also, I need to use a large blur radius.
> > > I've done this in the past by starting off with a small blur raidus and
> > > progressively reducing the selection, increasing the (gaussian) blur
> > > radius as I did so.  What is the simplest way to do  this?   If I just
> > > apply a gaussin blur with a large radius  to my selection is uses values
> > > outside the selection in calculationg the new values near the boundary
> > > of the selection.
> > 
> > Copy your selection, paste it to a new layer and blur that layer. Does
> > that give the desired result?
> 
> I don't believe so.   I tried it.   It still used pixels outside the
> selection in computing the new pixel values in the desired region.  In
> this case, those values were zero, so that lightened the region at the
> edges.

Did you check the "Lock alpha channel" button in the Layers dialog?

-- 


Olivier Lecarme
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Re: [Gimp-user] Applying large blur only to selection

2009-05-31 Thread Leonard Evens
On Sun, 2009-05-31 at 08:39 +0200, Sven Neumann wrote:
> Hi,
> 
> On Sat, 2009-05-30 at 21:24 -0500, Leonard Evens wrote:
> > I want to blur the sky so that only pixels in the selection are used in
> > computing the new values.  Also, I need to use a large blur radius.
> > I've done this in the past by starting off with a small blur raidus and
> > progressively reducing the selection, increasing the (gaussian) blur
> > radius as I did so.  What is the simplest way to do  this?   If I just
> > apply a gaussin blur with a large radius  to my selection is uses values
> > outside the selection in calculationg the new values near the boundary
> > of the selection.
> 
> Copy your selection, paste it to a new layer and blur that layer. Does
> that give the desired result?

I don't believe so.   I tried it.   It still used pixels outside the
selection in computing the new pixel values in the desired region.  In
this case, those values were zero, so that lightened the region at the
edges.

I think there may still be some way to do it using layers, but I haven't
figured out how.   
> 
> 
> Sven
> 

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Re: [Gimp-user] Applying large blur only to selection

2009-05-30 Thread Sven Neumann
Hi,

On Sat, 2009-05-30 at 21:24 -0500, Leonard Evens wrote:
> I want to blur the sky so that only pixels in the selection are used in
> computing the new values.  Also, I need to use a large blur radius.
> I've done this in the past by starting off with a small blur raidus and
> progressively reducing the selection, increasing the (gaussian) blur
> radius as I did so.  What is the simplest way to do  this?   If I just
> apply a gaussin blur with a large radius  to my selection is uses values
> outside the selection in calculationg the new values near the boundary
> of the selection.

Copy your selection, paste it to a new layer and blur that layer. Does
that give the desired result?


Sven


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[Gimp-user] Applying large blur only to selection

2009-05-30 Thread Leonard Evens
I want to blur the sky so that only pixels in the selection are used in
computing the new values.  Also, I need to use a large blur radius.
I've done this in the past by starting off with a small blur raidus and
progressively reducing the selection, increasing the (gaussian) blur
radius as I did so.  What is the simplest way to do  this?   If I just
apply a gaussin blur with a large radius  to my selection is uses values
outside the selection in calculationg the new values near the boundary
of the selection.
-- 
Leonard Evens 
Mathematics Department, Northwestern University

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