By Bill Graham, Graphics Editor, mailto:email@example.com
I've always enjoyed stereo pictures. I had a Viewmaster when I was a kid, and would always check out the latest 3D movie as soon as it would come to the local theater.
In 1989, when Impulse released Turbo Silver 3.0 for the Amiga, they offered it as an upgrade to previous users along with the stereo LCD glasses from Haitex, which I still have. They work on a slow scan rate monitor like the 1084 only. There is quite a lot of software that supports the creation of stereo imagery, like Imagine, Vista Pro, and others. If you are fortunate enough to have a stereo still camera and a scanner, you can convert those images into Amiga stereo pictures.
I was never happy with the necessity of owning expensive special hardware to view stereo pictures and animations, and I worked to find a way so that any Amiga owner could make and view stereo stills and animations. I came up with a method that works on both ECS and AGA machines, and it allows the user who wants to create stereo imagery the ability to tailor the resolution to fit his machine.
What I did was come up with a way of making anaglyphic stereo imagery viewable on any Amiga monitor. The anaglyphs in this case are monochromatic, or shades of one color. But the only hardware you need to view them are the red/blue glasses found in comic book stores and in variety shops. This article will guide you through the process of making these pictures.
This how-to assumes several things. Firstly, that you have a source of stereo pictures, or the software to create your own. Secondly, you must have ADPro, a.k.a. The Art Department Professional. No other image processor will do, for reasons discussed later. And thirdly, you must be familiar with the first two and have a basic knowledge of Amiga graphics.
I will use as an example Imagine-generated stereo images, and you can adapt as necessary. Amiga graphics include a plethora of various aspect ratios, or the ratio of the vertical and horizontal aspect of individual pixels. Hi Res interlace is 6x7, the same as NTSC video, as is Lo Res non-interlaced. Imagine generates a Hi Res stereo image of 640x400 pixels with the left image taking up the odd numbered scanlines, and the right image taking the even scanlines. When this image is loaded into ADPro, it automatically stacks the left image on top of the right image. Other image processors must use the Deinterlace operator to separate the two images, and they discard one of the two images. This is why ADPro must be used.
Once this image is loaded, you crop away the bottom 200 lines, saving the top 640x200 image as the Left pic. You then reload the original, this time cropping away the top 200 lines, saving the remainder as the Right pic. You then Scale these two images back to 640x400 size, and save them again. You can overwrite the 640x200 images; you won't need them again. Then you load the Left pic, and bring up ADPro's palette control window. Using the RGB colorspace model, select the first color well, and set it to 15, 0, 0. If the final stereo pic will be for an ECS machine, the final stereo pic will have a maximum of 32 colors, 16 red, and 16 blue. If it's for an AGA machine, then you can use 128 red, and 128 blue. So select either the 16th or 128th color pot and make it 255,0,0. You'll need to use Spread to get the intermediate shades. Render this image with the palette Locked. Save the rendered image, load the Right pic, and do the same thing, only this time with shades of blue, i.e., 0,0,15 and 0,0,255 respectively. Remember, for an ECS image, you must render a 16-color pic all shades of red or blue, and for an AGA image it must be no more than 128 color pic all shades of red or blue. It's a good idea when rendering these monochromatic low color pix to use a fairly heavy non-ordered dithering, also. It is very, very important that no green or blue color is used when rendering the red pix, and that no green or red color is used when rendering the blue pix.
Once again, you can overwrite the 24-bit images if you are short on disk space, but until you get this method down pat you may want to keep them in case you screw up. Now Load the Left pic. Select the Interlace operator. ADPro will prompt you for a second image, which of course is the Right pic. Now bring up the palette Control window again, and for an ECS 32-color pic, create a 32-color palette with shades of red and blue as explained above. In other words, color pots 1 through 16 get 15,0,0 Spread through 255, 0,0. Color pots 17 through 32 get 0,0,15 Spread through 0,0,255. For an AGA image, color pots 1 through 128 get 1,0,0 Spread through 255, 0,0 and color pots 129 through 256 get 0,0,1 through 0,0,255.
For an ECS image, there is one more step prior to Rendering the 32-color pic. You'll need to scale the image horizontally by 50% to 320x400, or a Lo Res Interlaced image. AGA machines can display 256 colors in Hi Res, so no scaling is necessary. When Rendering these final images, it is very important that dithering is turned off completely. Render with the palette locked to your defined colors, and voila, save your Anaglyphic Stereo image!
These images work best on a high scan rate monitor like a 1950, though they will work on a 1084. And any Amiga program that supports the IFF standard will display them in full stereo. At a user group meeting a couple of years ago, we used Scala hooked to an NEC projection system to display the stereo images on a 20-foot screen, and the effect was awesome! The images are naturally dark, so for best viewing turn the room lights down low or off completely. It is easy to use FRED, the batch processing program that comes with ADPro, to make stereo animations using the same parameters as making still images.
You can see some examples of stereo stills and animations created in this manner by going to http://is.eunet.ch:80/~aminet/dir s/pix_bill.html