Blending overlapping images WITHOUT blending the background in too

[Alan Hewat]

I want to blend together two overlapping (monochrome) images so that
the overlapping parts are their average intensities.

But if I paste these images with paste control "blend" into a new
image with a black (or white) background, the background is blended in
too.

Is their a paste mode that will not also blend in the black background
? Or can I set the background to something that won't be blended in
when I paste onto it ?

Alan.
______________________________________________
Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
<[hidden email]> +33.476.98.41.68
        http://www.NeutronOptics.com/hewat
______________________________________________

[Christophe CHAMOT-2]

Hello Alan,

The simpliest way I suppose is to choose  "Transparent-zero" as paste
mode in Edit > Paste Control ...
Then copy and paste, the black bacground will not be averaged.

Hope it helps.

Alan Hewat a écrit :

> I want to blend together two overlapping (monochrome) images so that
> the overlapping parts are their average intensities.
>
> But if I paste these images with paste control "blend" into a new
> image with a black (or white) background, the background is blended in
> too.
>
> Is their a paste mode that will not also blend in the black background
> ? Or can I set the background to something that won't be blended in
> when I paste onto it ?
>
> Alan.
> ______________________________________________
> Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
> <[hidden email]> +33.476.98.41.68
>         http://www.NeutronOptics.com/hewat
> ______________________________________________
>  

--
Christophe CHAMOT
Responsable Technique PLATIM
IFR128 BioSciences Lyon-Gerland
04.72.72.87.62
www.ifr128.prd.fr/PLATIM

[Christophe CHAMOT-2]

Mmmmh,

I was a bit too fast for responding. If you want to average objects
without average the background, not only paste non-zero pixels, the
simpliest way is to extract the objects.

If img1 is the destination image and img2 the image to be blended, I
will threshold my objects (Image>Adjust>Threshold) in img2, then create
a selection (Edit>Selection>create selection) then copy/paste these img2
objects on img1 in blend mode.

Other ways to proceed are welcome ...


Alan Hewat a écrit :

> I want to blend together two overlapping (monochrome) images so that
> the overlapping parts are their average intensities.
>
> But if I paste these images with paste control "blend" into a new
> image with a black (or white) background, the background is blended in
> too.
>
> Is their a paste mode that will not also blend in the black background
> ? Or can I set the background to something that won't be blended in
> when I paste onto it ?
>
> Alan.
> ______________________________________________
> Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
> <[hidden email]> +33.476.98.41.68
>         http://www.NeutronOptics.com/hewat
> ______________________________________________
>  

--
Christophe CHAMOT
Responsable Technique PLATIM
IFR128 BioSciences Lyon-Gerland
04.72.72.87.62
www.ifr128.prd.fr/PLATIM

[Alan Hewat]

Thanks again Christophe. But my images do not contain distinct objects
but are 8-bit; it it is difficult to define a specific threshold. The
best result I got was to use paste control MAX, which is not an
average of course, but at least it ensures that no bright features in
either image are missed.

Frankly, I can't see the point of the paste control BLEND if it also
blends in a black (or white) background, and indeed none of the macro
examples use it AFAICS.

Alan.

2009/8/13 Christophe CHAMOT <[hidden email]>:

> Mmmmh,
>
> I was a bit too fast for responding. If you want to average objects without
> average the background, not only paste non-zero pixels, the simpliest way is
> to extract the objects.
>
> If img1 is the destination image and img2 the image to be blended, I will
> threshold my objects (Image>Adjust>Threshold) in img2, then create a
> selection (Edit>Selection>create selection) then copy/paste these img2
> objects on img1 in blend mode.
>
> Other ways to proceed are welcome ...
>
>
> Alan Hewat a écrit :
>>
>> I want to blend together two overlapping (monochrome) images so that the
>> overlapping parts are their average intensities.
>>
>> But if I paste these images with paste control "blend" into a new
>> image with a black (or white) background, the background is blended in
>> too.
>>
>> Is their a paste mode that will not also blend in the black background
>> ? Or can I set the background to something that won't be blended in
>> when I paste onto it ?
>>
>> Alan.
>> ______________________________________________
>> Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
>> <[hidden email]> +33.476.98.41.68
>>        http://www.NeutronOptics.com/hewat
>> ______________________________________________
>>
>
> --
> Christophe CHAMOT
> Responsable Technique PLATIM
> IFR128 BioSciences Lyon-Gerland
> 04.72.72.87.62
> www.ifr128.prd.fr/PLATIM
>

--
______________________________________________
Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
<[hidden email]> +33.476.98.41.68
        http://www.NeutronOptics.com/hewat
______________________________________________