The following steps will show you how to create a seamless pattern tile without using filters in Photoshop version 4.0.
1. Start with a new file, 100x100 pixels, in RGB Color. Select pale yellow as a foreground color and dark red as a background color. The filter we'll be using uses foreground and background colors to create its effect. Apply Filter/Sketch/Halftone Pattern, with the Pattern Type set to Circle.
2. There are probably seams in the image you've just created. To check, use Filter/Other/Offset, with the Wrap Around radio button checked. The horizontal and vertical offset amounts are 50 and 50 (see Figure 4.8). This way, the seam will appear through the middle of the image, where it will be easier to see and to clean up.
3. There are now a number of ways to clean up that ugly seam. Many people use the Rubber Stamp tool, but I prefer to use the Smudge tool. It's a lot like finger painting. Just drag the Smudge tool, set to a small or medium brush size, across the center seam a couple of times. You can constrain the tool (as you can many other Photoshop tools) to a straight line by holding down the Shift key while you click the Smudge tool at either end of the straight line you're creating.
Another way to clean up those seams is to grab a piece of the image and copy it and paste it over the seam. Use the Lasso selection tool to make a small, irregular selection. Apply Select/Feather at 2 pixels. Apply Edit/Copy, (or Control+C on Windows, Command+C on the Mac), Edit/Paste (or Control+V on Windows, Command+V on the Mac), and drag or nudge (using the arrow keys) the patch over a seam. Continue patching until all the seams are covered. You'll need to apply Layers/Merge Down before you can save the finished file.
A third method to clean up pattern tile edges is to use a paint tool. Since this pattern tile is made up of a very soft texture, you can clean up the seams using the Airbrush tool set to a small brush size and low opacity setting.
Now, fill a larger selection to check how your image will look when it is tiled and used as a background. Open a new file (or Control+N on Windows, Command+N on the Mac), set to 300x300 pixels. This is large enough to show the pattern tiled. Return to the seamless tile you've created. Apply Select/All (or Control+A on Windows, Command+A on the Mac), Edit/Define Pattern.
4.Next, select the new file, and apply Edit/ Fill. Within the Fill dialog box, select Use, Pattern; Opacity, 100%; and Mode, Normal. The results will appear as shown in the example above. If you see any obvious seams when the tile is repeated, you can clean them up in the original file, using the smudge tool or the patch method. Save this file as a .tif file, because we'll be using it in Chapter 5 to demonstrate how to lower contrast in backgrounds for web pages.