On Sat, 14 Apr 2007 11:35:38 -0400 Joshua Simons wrote:

On Mon, Dec 05, 2005 at 08:08:13PM -0800, patman at aracnet.com

wrote:
>>
>> I also tried Carol's "removing background" tutorial: >>
>> http://carol.gimp.org/gimp2/basics/backgroundremoval/ >>
>> But it does not describe the "Add the decomposed image as a mask" portion.
>>
>> Can some explain it or point to a tutorial on the subject? >>
>Dialogs-->Layers
>
>in that dockable dialog, right click on the layer you would like to mask
>and select "Add Layer Mask" (i am typing this from memory so no >guarrentee on the exact wording).
>
>there will be a dialog with a choice of mask color/opacity. just stick
>with the default since the next step is to copy another image to it. >
>Decompose gives several layers. i would convert the decompose image to
>rgb (some of the gimps had problems copying grayscale and i cannot >remember which ones). Edit-->Copy on the layer you want as a mask >Edit-->Paste to the mask area on the target image. >
>black on masks is transparent, white is opague. gray is a little of >both.
>
>is that what you asked?
>
>carol
>

When I try the above Edit->Paste to create a layer mask containing an image,
I get a Floating Selection layer rather than anything in the layer mask. Can
anyone help?

I think you need to anchor the image first. Make a layer, paste and then anchor to the layer.

Owen

On Saturday, April 14, 2007 8:35 am, Joshua Simons wrote:

I am trying to blend two exposures using the 2nd technique ("Layer   Mask")
described at this URL:

http://www.luminous-landscape.com/tutorials/digital-blending.shtml

To use this given two exposures, E1 and E2, I need to find a way to   use E1
as a layer mask for E2. Is that possible using GIMP?

What you need to do is create the layer mask on the target layer where you want to paste E2 . Then copy E2. Be sure no layers above your target layer are visible. Make sure the mask is active by clicking on it in the layers dialog. Then paste the copied image. It will become a floating selection. Then anchor the floating selection. That will merge it into the layer mask.

Quoting Joshua Simons :

I am trying to blend two exposures using the 2nd technique ("Layer Mask")
described at this URL:

http://www.luminous-landscape.com/tutorials/digital-blending.shtml

To use this given two exposures, E1 and E2, I need to find a way to use E1
as a layer mask for E2. Is that possible using GIMP?

The quickest way that I know of is to drag the thumbnail of E1 from the Layers window to the Channels window. Then you click on the square, red button ("Replace the selection with this channel"), go back and activate layer E2, and perform an "Add Layermask" initializing the layermask to "Selection".

I have written a Script-fu which will create a selection from the current drawable which simplifies the above process a little:

* Perform Select->None. (because the script honors the selection) * Perform "Select->From Drawable" on E1. (this command is added to the Select Menu when you install the script) * Perform an "Add Layermask" on E2; initializing the layermask to the "Selection".

The script is available at http://www.flashingtwelve.brickfilms.com/GIMP/Scripts/layer-select.scm if you choose to use it. There are two other commands added: "Select->Layer Bounds" (which just makes a rectangular selection the same dimensions as the layer) and "Select->To Layer" (which creates a new layer from the selection using the FG and BG colors).