Hi,

On Tue, 2006-12-12 at 18:43 +0000, David Marrs wrote:

Unfortunately,
selecting the mask, hitting copy and then selecting a new layer and hitting paste doesn't work; the mask gets added as a floating selection with its position changed and when I anchor it, it is merged directly into the selected layer instead of being applied as a mask.

You need to create a layer mask first, then paste into the layer mask.

The other problem comes when I try to reposition the layer being masked.

If you do what I suggested above, you will get a floating mask that you can position before anchoring it.

Sven

I am uncertain about what you are attempting so you will forgive me if my response is completely off-base. Firstly, layermasks "choose" (or blend) between two images, the layer to which it is attached AND "everything underneath". Your description is confusing because you don't really specify what is to be blended with the current layer. By having only one layer visible at a time, the "everything underneath" will be transparent; which may be precisely what you intend (or perhaps you will put something there after your positioning is complete?).

Assuming that you are only concerned with the positioning of the mask relative to a single image (a single layer), I would propose that a channel mask might be a more appropriate solution. Taking, for example, several different layers over which you wish to place a text label: create your text and perform an Alpha to Selection, Invert your selection, perform "Select->Save To Channel", and make the newly created channel visible. (You can change the color and opacity of the channel mask if you wish, or leave it at 50% opacity.) Once you have done this, you can individually select your layers and move/transform them to see how the end result would appear.

When you have the layer positioned as you like, you should hide your channel mask, perform a Channel To Selection (using the button at the bottom of the Channels dialog), and add a layermask to the appropriate layer (initializing it to the Selection). At this point, I am unclear how you should proceed because I don't know if you wish the mask (the text label in the example) to be a transparency or something else. If a transparency, you are basically finished; if an image (or a solid color, gradient, pattern, etc) then put that image on a visible layer beneath the one with your layermask.

--------------------------------------------- David Marrs wrote:

I've been trying to accomplish some things with layer masks that I don't believe are currently possible. Please correct me if they are. I've been thinking about how to solve the problem and thought I'd ask the

opinion of the

community before posting a feature request to bugzilla.

I want to apply the same layer mask to a number of stock photos. In

this case

the mask is text but it could be anything. I want to get the best

image for the

mask and this means not only trying different photos but also aligning

those

photos for best composition.

As far as choosing from a selection of images goes, the easiest thing

in my

mind would be to create one layer mask and then paste it to other

layers. Then

I'd switch visibility between them to see which I prefer. Unfortunately, selecting the mask, hitting copy and then selecting a new layer and

hitting

paste doesn't work; the mask gets added as a floating selection with its position changed and when I anchor it, it is merged directly into the

selected

layer instead of being applied as a mask.

The other problem comes when I try to reposition the layer being

masked. The

idea is to apply the mask and then establish the best position for the

image

beneath it by using the move tool. Unfortunately, moving the layer

also moves

the mask and I don't seem to be able to move one independently of the

other.

In summary, masks seem to be dependant on their layers and can't easily be moved either within or between layers. I'd like it if layer masks were independent of one another to make such flexibility possible. Is this a desirable change? Are there side effects of this that cause problems?

Is it

already possible?

--------
"It is amazing what you can accomplish if you do not care who gets the credit." -- Harry S. Truman

On Tue, 12 Dec 2006 18:43:47 +0000, David Marrs wrote:

I want to apply the same layer mask to a number of stock photos. In this case the mask is text but it could be anything. I want to get the best image for the mask and this means not only trying different photos but also aligning those photos for best composition.

Although this is not implemented yet in the current GIMP, what you are trying to do for your composition could be done easily once "masking groups" or "clipping groups" are implemented. This feature, which exists in some other popular image manipulation program, allows you to group several layers and apply a single mask to the whole group.

There is an old GIMP enhancement proposal about this feature: http://bugzilla.gnome.org/show_bug.cgi?id=51112

With this feature, you could have all your stock photos as layers in the same masking group and toggle their visibility or reposition them individually while the same mask is always used. I only use GIMP myself but I have seen some designers using that feature in other programs with great efficiency. It is very useful when you are working on a composition and you want to change some masked layers without changing the mask itself. Or vice-versa, when you want to change the mask without having to change several layers using that mask.

It is too late to add that feature to GIMP 2.4 and it is probably not appropriate for 2.6 (unless the scope of 2.6 changes significantly) but it would be nice if someone could work on this for GIMP 3.0.

-Raphaël