[Award Winner] Explanation of Layer Masks in GIMP(and PS)

[jfrazierjr]

The final image result now looks like the first attached image(which looks like the first image in the original post).


Not that sexy eh? Rather boring right? True dat.

Now, let's begin to play with our existing layer mask to see what we can do with it. The good thing about layer masks is that you can edit them by "painting" either white or black to edit how the underlying layer shows up. Remember white shows through and black does not with anything in between being partially shown. So... let's get some variable color to show through and get rid of the hard line transition between the two colors.




In order to do this, Select the layer mask on the layer in question:



Note than when selected the thumbnail, either the layer OR the layer mask will have a slight white outline. In this case, we have the layer mask selected, so any operation we do will affect the mask, NOT the layer. What we now want to do here is apply some Gaussian Blur to get the two colors to blend. I used around 300 px blur to get to the final image.

Now, remember since we are not affecting the layer itself, this is a totally non destructive technique. Had we used the same technique as in the original post's second example, and blurred the color/alpha layer, then that layer would be permanently altered, and thus we would loose a lot of flexibility. However, since we just modified the layer mask and not the original layer, we have the blur but with no changes to the underlying layer.

You could do all sorts of other things such as directly painting white onto the layer mask, which would allow the layer to show though.

ONE THING THAT IS VERY IMPORTANT: When you want to modify actual layer the make SURE you have clicked on the layer thumbnail icon, or your will be modifying the mask. Likewise when you want to modify the layer mask itself.

You could also use a layer mask to create a gradient, again, without using any destructive techniques. In order to do this, I am going to delete the existing layer mask and add a new one. However, this time, I will select the "Black" radio button. Now, select the layer mask and change the foreground/background colors back to black/white. Click on the layer mask in the Layers dialog and select the Gradient tool. Now, apply the gradient to the layer mask. Note how the layer mask



is not a gradient and how the base image follows that gradient to merge the two color layers? This is the effect we are after. Now, again, we can change either color layer directly and the gradient effect would remain exactly as it is now, just with different colors, and that is the power of layer masks.

[jfrazierjr]

Now, what if you want to get some more control over the actual layer mask? How can I see the actual layer mask? WE CAN DO THAT.


On the layer, right click and select show layer mask. This shows the actual layer mask as seen in image two. Now, any changes you make here will show up in the layers, just like before.


What if you want to see the image without the layer mask? You can temporarily disable a layer mask if you like.


Likewise, if for whatever reason, you no longer need the layer mask, you can delete it also from the right click menu. There is also a menu option called "Apply Layer Mask".


What this does is merges the layer mask directly into the layer.

See how the layer mask is gone, BUT the effect is blended into the underlying image on that layer?

I tend to NOT like this since it is a permanent change to the underlying layer and thus we loose our flexibility which is the reason for using the layer masks in the first place.

[jfrazierjr]

There will be a bit more to come over the next day or so, but I hope this is more than enough to get anyone started with using layer masks. What I have presented the real "meat" of using layer masks and why they are so darn useful.

If anyone wants to ask any questions or if there is anything you don't understand(or want to add) please feel free.

[bryguy]

Whoah dude, this is awesome. Ive always wondered how to use layer masks, and so hopefully Ill be able to now (well, after I actually read it. Right now I just skimmed cause Im tired and off to bed)


5 stars!

[jfrazierjr]

Whoah dude, this is awesome. Ive always wondered how to use layer masks, and so hopefully Ill be able to now (well, after I actually read it. Right now I just skimmed cause Im tired and off to bed)

Thanks, that's exactly why I wrote it, for people who have so far been intimidated or just have not taken the time to learn how layer masks work. I hope this really helps you, and remember, ask questions if you need to. One thing I have found that this technique is really good for is blending various types of photo realistic texture fills. Check out my Some Creek thing for a very simple example. http://www.cartographersguild.com/sh...ighlight=creek

[xv43]

This is good, thank you.

[jfrazierjr]

Hmmm... I am kind of surprised with the lack of response on this. Is this because people already know this information, no one is looking at this(in which case, I can understand the lack of answering!), it's non understandable yet or you don't see any application in your mapping technique, or is everyone just using PS and don't think this applies to you? (it does, but in a slightly different way).

[ransw]

jfrazierjr,

I am new to mapping, but I have got to complete drawing maps for work. Finding your tutotials on layers, I believe, will help me get through some rough learning curves putting density on these maps. There are a few things that I have to learn, e.g. controlling the blending of shapes/colour onto the background, blending of shapes/colour of the next top layer, etc. This piece on layer is quite helpful. Thanks.

[jfrazierjr]

jfrazierjr,

I am new to mapping, but I have got to complete drawing maps for work. Finding your tutotials on layers, I believe, will help me get through some rough learning curves putting density on these maps. There are a few things that I have to learn, e.g. controlling the blending of shapes/colour onto the background, blending of shapes/colour of the next top layer, etc. This piece on layer is quite helpful. Thanks.

Thanks for posting Ransw and welcome to the guild. Be sure to pop over to the Member Introduction forum and post a note saying hi. Also, once you start on your map(s) start one or more threads in the appropriate Work in Progress forum(s) and we will be more than happy to help.


Finally, please be sure to rate any tutorial threads use use. I would also highly suggest going through the Regional Map tutorial by RobA as there a TONS of useful techniques for GIMP and you can really learn a lot.

[Chris]

You've got me there. I had a slight idea how they work because I used layer masks as a beginner in tutorials but without realizing what exactly can be done with them. So even over 3 years after you made this tutorial I is still very helpful for beginners like myself!

Thanks a lot for that!!