source: http://www.thegoldenmean.com

Displace Filter, Page 4 - Tiling Maps

target image for tiling tutorial

Armed with the information provided thus far, it’s time to venture into actually applying the Displace filter to an image. As part of the standard install, Adobe provides a number of pre–made Displacement Maps. These are located in a folder with that name inside the PlugIns folder on your hard drive.

Adobe chose to save these DMaps as RGB files. There’s nothing magical about the files themselves — they are just PSD files, which means that we can open and examine them in Photoshop. They appear as little, somewhat oddly colored images. Remembering that only the first two channels of any DMap have a bearing on the effect of the filter, you will notice that the third channel (blue) is just blank white. But the other two channels (red and green) are really quite intricate and sophisticated in some of their maps. You will note that Schnable has identical channels, but look at how different the channels are in one like Random Strokes. If you keep in mind what we now know about brightness values and channels with regard to displacement, it’s a stimulating mental challenge to look a the maps and imagine their impact on a picture.

We remember from the previous page that a DMap which is smaller than the Image file can be applied either as a tiled pattern or stretched to fit the larger image. I have to assume that it was Adobe’s intention to have these small DMaps tile when applied to an image, so that’s how I will use them for this part of the demonstration. Below you will see four of the DMaps applied to an image. I have shown the two channels of the DMap “deconstructed” (red followed by green) followed by its effect. Instead of using a simple grid target I’ve opted to use a photograph for a test file, the landscape displayed at the top of this page. In order to maintain consistency, in every case the settings were vertical: 5%; horizontal: 5%; tile; repeat edge pixels. These percentages are not very high, but they have a strong effect on a relatively low resolution file. Please realize that for a stronger effect or for a higher resolution file you can go much higher with these numbers - up to 200% I think. A setting of 5% would be almost undetectable at 300 DPI.

Schnable map
result of schnable
mezzo map
effect of mezzo map
random stroke map
effect of random stroke
twirl map
effect of twirl map

Making your own

Pretty neat, aren’t they? Spend some time examining the DMaps Adobe provides. In addition to their tiling properties, the sophistication of the shapes and density values are a good lesson for when you start to make your own. Which is of course the next step in this process. My impression of these supplied files is that they provide a descriptive surface effect to an image — a painted, brush–stroke sort of feel. That’s amazingly useful if that’s the feel you are going for. (Sidebar: one reason I chose this test image was because of the rippled reflection in the water. I swear this was a photograph, and it looked just like this in real life. But… what if you wanted to make a watery reflection where there was none? This is the next level of sophistication. There are numerous tutorials out there that tell you how to make a reflection - you copy the sky into a new layer, rotate it 180°, maybe set its blending mode to multiply, fiddle with color and brightness… but it’s still a smooth surface. So maybe you apply the Zig Zag filter set to pond ripples or something. Does it look real? Displace is the tool you need to create a truly believable reflection on a surface of water.)

Now that you know what this filter does you are free to apply it to your own needs. Here’s an example. I was wandering around town a while ago and saw a health club on the first floor of a building. There was a big plate glass window, but I guess the step aerobics class felt conspicuous sweating in front of anyone passing by, so they replaced the window with a specialty glass that lets in light but obscures the view. I’m sure you’re seen similar windows. This one was made with narrow parallel vertical lenses so it stretched and distorted the view of the room into a pattern of vertical lines. It was gorgeous! With that image in mind, I set out to make a DMap that would do the same thing. With a series of narrow white to gray and black to gray linear gradients I was able to do just that. Note that, since I wanted the majority of the effect to be vertical displacement, in this case I did not set horizontal and vertical to the same percentages: instead I used 3% for horizontal and 25% for vertical, and of course set to tile and repeat edge pixels. Note that channel A and B differ significantly. Also note that, because of the extreme displacement vertically the top and bottom edges got very raggedy, so I did a little handwork to mask that and to make it look like a window!

privacy glass map
effect of privacy glass map

The next topic for exploration deals with using Displace to subtly or radically manipulate the shape of an image. For this we will put small, tiling DMaps aside and work with maps the same size as the graphic itself. Adobe doesn't offer any pre-made DMaps for this - how could they? These need to be custom made, and that's just what we're going to do next.

On to page five: Warping a graphic

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