Quoting Zhang Weiwu :

I wish to achieve the effect to add a deep pucker on the skin, as of the bone is broken underneath the sking or there is a joint underneath. Or should I use the word "wrinkle" or "crinkle", I am not sure. I am a new gimp user who just managed to learn conceptual things like layers, path, selection, mask and channel, and now I don't know where to start to read if I wish to get it done.

You might try using the "Grow" and "Shrink" options of the IWarp filter ("Filters->Distorts->IWarp...").

On 2008-01-29 saulgoode@flashingtwelve.brickfilms.com Wrote

Quoting Zhang Weiwu :

I wish to achieve the effect to add a deep pucker on the skin, as of the bone is broken underneath the sking or there is a joint underneath. Or should I use the word "wrinkle" or "crinkle", I am not sure. I am a new gimp user who just managed to learn conceptual things like layers, path, selection, mask and channel, and now I don't know where to start to read if I wish to get it done.

You might try using the "Grow" and "Shrink" options of the IWarp filter ("Filters->Distorts->IWarp...").

Thanks. Actually I tried these things first, this is the first plugin I managed to use, it can hardly achieve the effect having "pucker" on the skin. I knew it's difficult to express what I wish to have, thus here is attached a picture of sking with no pucker and a picture sking with a "pucker". Have a look at the screen you can also correct my expression (actually, I am not sure at all of pucker is the right word).

??? wrote:

On 2008-01-29 saulgoode@flashingtwelve.brickfilms.com Wrote

Quoting Zhang Weiwu :

I wish to achieve the effect to add a deep pucker on the skin, as of the bone is broken underneath the sking or there is a joint underneath. Or should I use the word "wrinkle" or "crinkle", I am not sure. I am a new gimp user who just managed to learn conceptual things like layers, path, selection, mask and channel, and now I don't know where to start to read if I wish to get it done.

You might try using the "Grow" and "Shrink" options of the IWarp filter ("Filters->Distorts->IWarp...").

Thanks. Actually I tried these things first, this is the first plugin I managed to use, it can hardly achieve the effect having "pucker" on the skin. I knew it's difficult to express what I wish to have, thus here is attached a picture of sking with no pucker and a picture sking with a "pucker". Have a look at the screen you can also correct my expression (actually, I am not sure at all of pucker is the right word).

I think you would call it a 'crease' or a 'fold'.

Andrew

??????

I wish to achieve the effect to add a deep pucker on the skin,

...

I knew it's difficult to express what I wish to have, thus here is attached a picture of sking with no pucker and a picture sking with a "pucker". Have a look at the screen you can also correct my expression (actually, I am not sure at all of pucker is the right word).

At first glance it looks like a simple issue, just to use some plug-ins. Look deeper into it it's isn't simple.. Seems to me there are two options there:

1. Copy half of the sking, paste into a new layer with trasnparency, use IWrap on both layers (the "move" method), move both layers towards the 'pucker', make smart use of alpha channel and drop-shadow effect. This is too difficult to create something that really looks like 'pucker'. 2. Use the displacement map filter, as I was suggested through a private email from the list. The problem is lack of good methodology to create approciate X/Y Displacement Coefficient layer. Whatever I create, it just doesn't look like.

On Tue, 29 Jan 2008 11:11:00 +0800, Zhang Weiwu wrote:

I wish to achieve the effect to add a deep pucker on the skin, as of the bone is broken underneath the sking or there is a joint underneath. Or should I use the word "wrinkle" or "crinkle", I am not sure. I am a new gimp user who just managed to learn conceptual things like layers, path, selection, mask and channel, and now I don't know where to start to read if I wish to get it done.

This is accomplished by adding wrinkles to the skin. To do this, you create your skin layer first. Then add a layer on top of that and fill it with the shading for the wrinkles. Shading (also known as shadow maps) is always done with a layer that is desaturated. The shading layer is then blended with the layer below using one of the layer blend modes, often Grain Merge, Multiply or Overlay though others may work better depending on the skin texture. This gives the skin layer the appearance of having a shape that is light unevenly - ie it looks like wrinkles.

A smooth version of wrinkles was originally included in my book "The Artist's Guide to GIMP Effects" but then we decided to add it to the web site instead:
http://www.graphics-muse.org/artistsguide/?page_id=65

This example is not exactly like what you're looking for though the idea is the same. This example uses a desaturated "wave" over witch a shadow from some text is applied. In your case, the wave layer from this example would be the wrinkle layer for your project. Adjust it accordingly to increase contrast to give the wrinkles more distinct edges.

On Jan 30, 2008 3:47 AM, Michael J. Hammel wrote:

On Tue, 29 Jan 2008 11:11:00 +0800, Zhang Weiwu wrote:

I wish to achieve the effect to add a deep pucker on the skin, as of the bone is broken underneath the sking or there is a joint underneath. Or should I use the word "wrinkle" or "crinkle", I am not sure. I am a new gimp user who just managed to learn conceptual things like layers, path, selection, mask and channel, and now I don't know where to start to read if I wish to get it done.

This is accomplished by adding wrinkles to the skin. To do this, you create your skin layer first. Then add a layer on top of that and fill it with the shading for the wrinkles. Shading (also known as shadow maps) is always done with a layer that is desaturated. The shading layer is then blended with the layer below using one of the layer blend modes, often Grain Merge, Multiply or Overlay though others may work better depending on the skin texture.

I must disagree -- for something with multiple color layers, like skin, it generally looks better to use some coloration in order to make the shadows (for example, with Grain merge and the sample picture provided, I might use a mild reddish-pink tint. Though I admit this is mainly effective when you draw the shadows cumulatively (eg. as a repeated application of this reddish-pink with Grain Merge drawing mode to a layer originally filled with RGB 128,128,128).

This gives the skin layer the
appearance of having a shape that is light unevenly - ie it looks like wrinkles.

A smooth version of wrinkles was originally included in my book "The Artist's Guide to GIMP Effects" but then we decided to add it to the web site instead:
http://www.graphics-muse.org/artistsguide/?page_id=65

This example is not exactly like what you're looking for though the idea is the same. This example uses a desaturated "wave" over witch a shadow from some text is applied. In your case, the wave layer from this example would be the wrinkle layer for your project. Adjust it accordingly to increase contrast to give the wrinkles more distinct edges.
--
Michael J. Hammel Principal Software Engineer mjhammel@graphics-muse.org http://graphics-muse.org ------------------------------------------------------------------------------ The aim of every artists is to arrest motion, that is life, with artificial means. -- William Faulkner

On Wed, 2008-01-30 at 08:02 +1030, David Gowers wrote:

On Jan 30, 2008 3:47 AM, Michael J. Hammel wrote:

This is accomplished by adding wrinkles to the skin. To do this, you create your skin layer first. Then add a layer on top of that and fill it with the shading for the wrinkles. Shading (also known as shadow maps) is always done with a layer that is desaturated. The shading layer is then blended with the layer below using one of the layer blend modes, often Grain Merge, Multiply or Overlay though others may work better depending on the skin texture.

I must disagree -- for something with multiple color layers, like skin, it generally looks better to use some coloration in order to make the shadows (for example, with Grain merge and the sample picture provided, I might use a mild reddish-pink tint. Though I admit this is mainly effective when you draw the shadows cumulatively (eg. as a repeated application of this reddish-pink with Grain Merge drawing mode to a layer originally filled with RGB 128,128,128).

True, but that's something you learn to do after you've learned what shadow maps do and I don't think the original poster was familiar with those yet. My feeling is that it's a little easier to understand what the shadow map is doing if you can see it's nothing but levels of light and dark (re: a desaturated layer). Adding color is an extension to that.

I actually learned to do exactly what you suggest by first learning shadow maps and then tinkering with the process.

So I guess you can modify my answer to change "always" to "often, especially when you're first learning shadow maps". :-)