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

[jfrazierjr]

Ok.. up next, we get to the real meat of the tutorial show you how to actually use a layer mask. Now, remember from the previous posts that when painting on a layer mask, that black is opaque and white is transparent.

• We start by creating a new layer for the bank of our stream.
• Fill this new layer with an appropriate texture, in this case, I used Gravel_blu-aT.png from the CSUAC (which is where the rest of the textures come from).
• Next, we Add a layer mask to the gravel layer, in this case, I have chosen white so that nothing shows through.
• Select a largish brush, perhaps cranking up the multiplier some and select your foreground color to white.
• Now, making sure you have the Layer mask selected in the Layers dialog(it has to have a slight white halo around it, though it may be hard to tell since the mask is white!) Begin carving out the rock texture using your brush to reveal the water underneath.
• Just to show the technique, once I finish my main shape, I switch to a smaller brush and back to white and draw in a small island shape.

You should have something like this image


Not to very exiting is it eh? The banks are "hard" the water appear the same depth every where, and the rocky texture is just way overpowering over that much space right? Don't worry, we will fix those issues very shortly.

[jfrazierjr]

Here is the next video.


Now, we will clean this up a bit and make it a bit prettier.

• Start by selecting a med/small brush
• Set the foreground color to 50% gray (808080)
• Now, trace over the edges of the creak walls on the layer mask for the Rocky Bank layer. You don't have to be perfectly symmetrical (and should not!), nor do you have to trace every single square inch. Notice in the video that I left some gaps and did NOT put down some grey in a few places.
• Finally, Apply a Gaussian Blur of perhaps 50 px. You can use less or more as your taste suites you.

Also, note that you could just as easily used multiple shades of grey on the mask layer. Perhaps Black, 80% gray, 50% grey, 30% grey, and white. This is all up to you as to how much you want the blending. The blur will do some of the blending for you, but with multiple greyscale passes in various places, this gives you much finer control over the final product. I did not feel like spending a ton of time on it, which is why I only did one single extra shade of gray in addition to the base black and white.

Here is what I have now, and yours should look something like this:


Hmm.. now this is looking much better. The water appears to get "shallower" in near the banks and in a few places, there are even some small pools of the stream. But UGH. the repeating rocky texture is killing my eyes you say! Fear not... we shall tone that down in just a few minutes. Stay tuned for the next exciting episode of "Playing with Layer Masks".

[jfrazierjr]

Ok. Yet another small update.

Ok, so in this episode, we will use the exact same technique to add some ground cover.

• Create a new layer
• Add a texture to the layer, in this case, I am using Grass_mud_jhd.bmp, again from the CSUAC.
• Add a layer mask set to White
• Change the layer opacity down to around 50% so you can see the lower layer
• Select the new layer mask you just created in the layers dialog
• Using a med/large brush Pencil set to black, draw out the river and parts of the bank in whatever pattern you wish to show
• Turn the opacity back to 100%
• With the layer mask still selected, Filters->Gaussian Blur around 50px, more or less to taste.

This produces something like the below image:

Now, we are starting to see something that looks like a creek bed in the wilderness. Next, we will add a tree texture with something like palm fronds.

[jfrazierjr]

Ok.... Yet another video update!


Ok... so after doing this a few times, I am going to skip go through this quickly. I used Succulent_green_jhd.bmp from the CSUAC for the reeds/trees/whatever you call them.

• Add new layer
• Will with Texture(above)
• Set Opacity to 50% or so
• Add layer mask(white again) and select it
• Med Large Black Pencil brush, brush out the water, rocks and undergrowth you want showing through
• Set opacity back to 100%

Here is the output:


This is coming along really nicely. At this point, we could call it quits and be done, but there seems to be just a bit missing... Specifically there needs to be a few shadows to kind of give it a bit more illusion of depth.

Next time, we will NOT be using any layer masks, but will be using a non descriptive technique to add a bit of shadows to the creek/stream and make it look a bit more like its 3 dimensional.

[jfrazierjr]

Ok.. Here is one more video update. This shows the real power of masks, so pay careful attention. Watch it several times if you want. Of course.... In this case, I just picked some textures semi randomly, so they are not what I would use in a final image.

What this means is that once you have have your layers set up, you can make pretty much any changes needed, color, etc and only the part the mask says to show will be visible in the image. Compare this to directly painting your image using the Clone tool and "painting" the pattern onto the image. This could take quite a lot of time, depending on how much of the image you need to cover with the texture, then changing the opacity, and painting a bit more, wash-rinse-repeat. Quite a bit more work eh???

Next time, I will be going back to the original image for the final touch ups which will include adding a 50% gray layer set to overlay and using the burn tool to add some shadows to the creek and a bit to the underside of the "trees" to give them a bit more depth.

[jfrazierjr]

Ok, here is the final Video in this part of the tutorial. In this one, we use some techniques to add some extra detail to the image to give it a bit more 3D look. THANKS A TON to Torstan for giving me a few pointers of which I will go back to the original water texture layer and make a few changes.

• On the Water Texture layer, do Colors->Invert. This changes the black ripples to white ripples
• Change the mode to Hard Light
• Set the Opacity down to about 30% or so
• Next, create a new layer below the Trees, but above the undergrowth, bank and water and fill with 50% gray
• Change the mode to overlay
• With a med-large fuzzy brush, and the dodge tool selected, paint in your shadows. Pick a direction for the light to come from and imagine the places where the light would be blocked and this is where the shadows would be.
• Paint in places in the creek where you want an illusion of more depth.
• Run a Gaussian blur. I picked 100px, but you could go higher or lower to taste.

Note that this part of the tutorial is totally subjective. Just play with it until you get something you like. Another possible technique to use here would be to use the Pencil tool to add in some solid black. Perhaps switching to various gray colors or dropping the opacity as you radiate outward from the darkest parts. Likewise, you could create multiple gray layers to be able to apply different amounts of blur..... It's all up to you.


Here is the final image:

Note that I am far from a master at getting shadows right. If I really wanted to get this right, I would have spent far more then a few seconds or so as limited by the Video format. You, playing at home can spend as much time as you need to get this as nice as you can. Also, I would probably go back and add second grey layer and add a lot more darkness around the treeline for shadows. The blur step really toned that down quite a bit.

[Absinth]

Great tutorial! Very helpful! Thanks for giving advice to the newless cluebies!

[jfrazierjr]

Great tutorial! Very helpful! Thanks for giving advice to the newless cluebies!

Well, thanks! You won't be a newbie for long. I started playing around in GIMP less than 5 months ago and most of what I know is due to many of the great people here and a bit of playing.

[torstan]

Glad to be of help. Good work on the tute!

[The Cartographist]

Nice Tut! I look forward to trying the stuff out (no time right now)...