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Part IV: Exploring Filters and Effects FIGURE 14-32 Using the Grid effect on your image and viewing it within the image window of GIMP. Notice how the Grid filter effect applies a mathematical grid directly over your original image. Jigsaw The Jigsaw filter (Filters  Render  Pattern  Jigsaw) can be used to turn your image into a jigsaw puzzle. Figure 14-33 shows the Jigsaw filter dialog box where you can make adjustments to your image. You can make adjustments to the horizontal and vertical placement of the puzzle pieces, adjust the beveled edges, or pick between square and curved jigsaw puzzle styles. Maze The Maze filter (Filters  Render  Pattern  Maze) applies a maze-like look to your image by completely overwriting the previous contents of the active layer and replacing the information with a random black-and-white m aze pattern. Figure 14-34 shows the Maze filter dialog box where you can make adjustments to your image. 418 Chapter 14: Using Image Creation Filters FIGURE 14-33 Creating a jigsaw-like pattern on your original image with the Jigsaw filter plug-in FIGURE 14-34 Using the Maze render effect to create a maze on your image 419 Part IV: Exploring Filters and Effects By selecting between multiple algorithms, you can choose among different types of maze overlays. Qbist The Qbist filter (Filters  Render  Pattern  Qbist) generates random texture information that is used to create interesting color gradients on preexisting images or new ones. Figure 14-35 shows the Qbist filter dialog box where you can make adjustments to your image. FIGURE 14-35 Using the Qbist filter effect to generate random patterns and textures for new image creation The Qbist filter generates random textures that you can use to create backgrounds, for example. You can use the presets found within the dialog box to select ones you like, or use the Open and Save buttons to load and create new ones. Sinus The last effect in the Pattern section of the Render filter menu is Sinus (Filters  Render  Pat- tern  Sinus). The Sinus effect lets you create striped textures for new images, or to replace old ones. Circuit Once you have finished looking at the Render menu’s patterns, move down to the Circuit option. Here, you can apply and/or create a new pattern that looks like a digital circuit. This filter is located in the image window menu under the Render menu. Run it by going to Filters  Ren- der  Circuit. 420 Chapter 14: Using Image Creation Filters Fractal Explorer With this filter, you can create fractals and multicolored pictures verging on chaos. Unlike the IFS Compose filter, with which you can fix the fractal structure precisely, this filter lets you per- form fractals simply. This filter is located in the image window m enu under the Render menu. Run it by going to Filters  Render  Circuit. Figure 14-36 shows the Fractal Explorer dialog box where you can make adjustments to your image. FIGURE 14-36 Using the Fractal Explorer to create new images with GIMP Gfig The Gfig filter (Filters  Render  Gfig) allows you to edit an image directly and gives you drawing tools for editing. The filter is more of a toolbox filled with things you can use with your composition. Figure 14-37 shows the Gfig filter dialog box where you can make adjustments to your image. 421 Part IV: Exploring Filters and Effects FIGURE 14-37 Using Gfig to create lines and other shapes on your drawing You can make lines, circles, and other geometric shapes. You will find using Gfig a more conve- nient process than trying to draw vectors and shapes with GIMP’s Paths tool. Lava This filter is located in the image window m enu under the Render menu. Run it by going to Filters  Render  Lava. In the Lava Filter dialog box you can make adjustments to your image and apply a flow-like blur, much like the effect of lava dripping down the side of a mountain. Line Nova This filter is located in the image window m enu under the Render menu. Run it by going to Filters  Render  Line Nova. Figure 14-38 shows the Line Nova dialog box where you can make adjustments to your image. You will also notice the image window with a preview of the image being rendered. 422 Chapter 14: Using Image Creation Filters FIGURE 14-38 Applying the Line Nova filter to an image and watching the application of it while rendering Sphere Designer The Sphere Designer filter (Filters  Render  Sphere Designer) allows you to design and create images with 3D spherical designs and textures. Figure 14-39 shows the Sphere Designer filter dialog where you can make adjustments to your image. You can use the Preview section to view your setting changes before you make them. You have many options to select from within the Sphere Designer, such as texture and light settings, as well as X and Y placement on the screen. 423 Part IV: Exploring Filters and Effects FIGURE 14-39 Using the Sphere Designer filter effect to create 3D images Spyrogimp This filter is located in the image window m enu under the Render menu. Run it by going to Filters  Render  Spyrogimp. You can select between many options such as Type and Shape of effect, as well as where the effect can be placed on the image. This is useful if you are trying to create a fence or grating effect in front of an image. You can also adjust the coloring if needed by clicking the color bar and clicking OK to apply the effect. In Figure 14-40 you can see the Spyrogimp filter creating a chain-link fence look in front of the current image. 424 Chapter 14: Using Image Creation Filters FIGURE 14-40 Create a chain-link fence in front of your image. Summary This chapter covered many of GIMP’s filters available for enhancing your digital images. Most of them, whether for lighting, noise, or rendering images from scratch, showed you how power- ful GIMP can be under the hood. The next chapter covers more of GIMP’s filter menu options, plug-ins, and filters for compositing effects. 425 Using Compositing Filters IN THIS CHAPTER Using edge detection for advanced compositing Taking advantage of GIMP’s sadly misnamed ‘‘Generic’’ filters Using one image to create another B ecause it is an image editor with an advanced layers system, one of GIMP’s primary uses is that of a compositing tool. In computer graphics, compositing is the art of mixing multiple graphic elements together to attain a specific visual look. A simple example of compositing would be if you take a picture of your friend and overlay text that says ‘‘Friend for Sale.’’ You might not be friends for long after doing such a stunt, but you’d have a good example of compositing in your hands. In advanced compositing examples, you can mix an image with itself to give it an ethereal glow or you can change a daytime scene to look like it was taken at night. Compositing consists of using a series of small steps and processes to influ- ence the final look of your image. The filters described in this chapter play into that process because they’re small, generally simple tools that can be used at each step to achieve the final composited result. Being as simple as they are, these tools are also often used for tasks that aren’t directly related to compositing. I’ll try to point out where a filter can be used as more than just a tool to help mix graphical elements together. That said, the filters in this chapter offer some of GIMP’s greatest abilities to dramatically influence the look of your final image, often completely chang- ing it from the original. Filters are easy to use and really quite fun. And when you use them effectively, you get some very powerful results. Working with Edge-Detect Filters Edge detection is a means of automatically generating a contour line to dif- ferentiate the various features of an image. At its simplest, you can use edge detection to generate an image that looks like a line drawing of your original, as shown in Figure 15-1. The results of these filters can look pretty odd and may seem useless, and as such these are some of the most overlooked 427 [...]... most 3D applications give you the ability to render a depth map A depth map is basically a grayscale image that defines how far away from the camera an object in the scene is Depending on the program, the generated depth map may define white pixels as farthest from the camera or black pixels as the farthest ones, but in GIMP, the whiter the pixel, the farther it is from the camera Figure 15-18 shows... names The left column lists the images you currently have open in GIMP The Filmstrip filter only has access to those images The panel on the right lists the images you want to use in this effect in the order you want them to appear By default, the only image in the right-side list is the one that you used to call the Filmstrip filter 4 47 Part IV: Exploring Filters and Effects To add images to the list... Offset, these values also control how the depth maps position the content relative to the camera The difference, though, is that because each Scale value adjusts one depth map independently of the other, you have more control Lowering the Scale value for one of the depth maps makes that map darker, thereby giving its content priority and effectively saying it’s closer to the camera than the other one... images, they are added to the right panel in the order that they appear in the left one This means that if you want these images to appear in a specific order that’s different than the one they use in the Available Images list, you need to manually add them one at a time in the desired order And if you have an item out of order, you need to select it as well as all of the images below it and click the Remove... put, this is just taking the pixels that you have at the border and copying them beyond the border so you can complete the matrix Wrap — Rather than just copying the same pixel over and over, you could try to use the pixels that are on the opposite border to complete your matrix Disregard the pixel and crop it — Your last option is to simply disregard these border pixels and crop them off after you finish... run it, the brightest parts of your image get brighter and larger In contrast, the Erode filter cuts away at these bright sections by increasing the size of the darker portions of your image as well as making them darker Figure 15- 17 shows what happens when you run the Dilate and Erode filters a couple times in a row on a single image Notice the stripes on the band around the hat When dilated, the stripes... below the right-side panel to get them out of the list Then you can add images back where they belong It’s a bit inconvenient this way, but until GIMP developers (or you!) modify this filter to provide controls for rearranging the order of items on these lists, we’ll have to deal with doing it this way Note The Filmstrip filter cannot load all of the images from a directory and use them for you The only... attribute the exact same size as the strip’s height FIGURE 15-23 The parameters available in the Advanced tab of the Filmstrip filter 449 Part IV: Exploring Filters and Effects The following list is a short description of each of the values in this tab: Image Height — This is the height of your source images relative to the overall height of the final result The default value of 0.695 sets the image... to be 69.5% of the overall height Image Spacing — This value controls how wide the space is between the images in the strip Set this value to zero if you want each image to butt right up to the next one Hole Offset — Increase this value to push the holes inward from the top and bottom borders of the final image Hole Width/Height — These sliders control the dimensions of the holes in the final strip If... looking at each pixel and using the pixels around it to define the matrix Figure 15-12 illustrates this for a 3x3 matrix and a 5x5 matrix Now, these matrices get a little tricky when you get to the border of your image If you’re evaluating the pixel that’s the farthest to the left, there are no more pixels to the left of that one that you can use to generate your matrix In these cases, you have three possible . as the basis for a fine mask, you can then quickly define the rest of your mask by painting on the outline image or using it as the starting point for selection and moving forward from there. The. Gaussian blur to each of them. Then one image is subtracted from the other. That dif- ference reveals the edges in the image. This method is really attractive because the Gaussian blur algorithm. Edge-Detect  Neon and GIMP gives you a window like the one that appears in Figure 15-8. FIGURE 15-8 The parameters window for the Neon edge detection filter Like the windows for all of the other edge detection