You will need:
1. Two adjacent 600-pixels/inch anaglyphs (i.e. anaglyphs that have an overlapping region; either top-to-bottom or left-to-right)
2. A full copy of Adobe Photoshop v3.0, or above
3. A computer capable of manipulating large images (at least 300 MHz, with 500 MB of available RAM)
Procedure (we will assume that anaglyphs go left-to-right):
1. In Photoshop, open up the left-hand anaglyph.
2. Select Image Size from the Image menu and record the print size dimensions (height and width).
3. Under the File menu, select New to create a new file. The dimensions should be able to accomodate two images side by side, so for image width enter twice the width of the left-hand anaglyph. For image height, enter the exact same height of the left-hand anaglyph (note: when working with top-to-bottom anaglyphs, the opposite should be true: double the height and keep the same width). For resolution, enter 600-pixels/inch, and for mode select RGB. Click OK.
4. Click on the left-hand anaglyph. Click on All in the Select menu. Under the Edit menu, select Copy.
5. Close the left-hand anaglyph (this will reduce memory waste) by selecting Close under the File menu.
6. Click on the new blank image.
7. Select Paste from the Edit menu. You will see the left-hand anaglyph appear. Hit the V key to select the move tool. Click on the newly pasted anaglyph and drag it so that it fills up the left half of the image space (the right half should be white).
8. Under the Window menu, select Show Layers (If the Layers pallette is already open, you will only see an option for Hide ayers. If this is the case, just proceed to the next step).
9. Click on black arrow in the upper-right hand corner of the layers pallette, and select Flatten Image from the menu options (this reduces memory waste by combining all layers into one).
10. Open up the right-hand anaglyph. Click on All in the Select menu. Under the Edit menu, select Copy.
11. Close the right-hand anaglyph by selecting Close under the File menu.
12. Click on the remaining image, and paste (Select Paste from the Edit menu). Now, both the left and right anaglyphs are in the same file.
13. In the Layers pallette (window with layers, channels, etc...), change the opacity of the new layer (Layer 1, which is the right-hand anaglyph) to 50%. This will allow you to see the overlapping portions of the two anaglyphs.
14. Hit the v key to select the move tool, and then click-and-drag the right-hand anaglyph until it overlaps the corresponding segment of the left-hand anaglyph. Fine adjustments can be made using the arrow keys. Rotation can be performed by selecting Rotate under the Transform submenu, which is in the Edit menu.
15. Once the right-hand anaglyph is properly alligned with the left-hand anaglyph, go back to the Layers pallette and change the opacity back to 100%.
16. If there is a noticeable boundary that disrupts the continuity of the full anaglyph, select the erase tool by hitting the e key.
17. Open up the brushes pallette by choosing Show Brushes under the Window menu.
18. Select a brush with soft edges. Larger brushes typically work better. To get a better idea of the brush size, you might need to change the cursor preferences. Do this by selecting Displays & Cursors from the Preferences submenu under the File menu. In the Painting Cursors box, click on Brush Size, and then OK.
19. Click on Show Options under the Window menu, and change the eraser opacity to 75%.
20. Center the eraser at the top of the boundary, and erase all the way down the image (you might find it helpful to hold down the Shift key while doing this to ensure that you draw a straight line). The eraser tool erases the upper image and reveals the lower image, and the soft edges allow a smooth transition .
21. If you are satisfied with your results, go to the Layers pallette, click on the black arrow at the upper-right hand corner, and select Flatten Image.
22. There should be quite a bit of white area in the right portion of the image. In order to save disk space, you should get rid of this by cropping the image. Click on the C key to select the crop tool, and use it to select the area of the anaglyph that you want to keep. Double-click inside the selection box when finished.
23. Save your image by selecting Save under the File menu.