This instructable assumes a working knowledge of weaving.
TC-1/Jacquard looms are special because each warp thread is controlled individually. That is, unlike most looms that use heddles to control patterns, with a TC-1 loom there never has to be a repeat in a pattern. Any of the 1760 warps can be up or down at any given time depending on the instructions given to the loom. Images for the loom need to be strictly black and white. When the TC-1 sees a black pixel, it knows to raise that warp, and when it sees a white pixel, it lowers the warp.
Step 1: Designing Your Image & Making a Repeat Pattern
The first step in designing a textile to be woven is to just draw something in Photoshop. In this case, I wanted to make something that resembled a toile. I like toile patterns because they show historical scenes in beautiful monotone repeats. Normally toile textiles are printed, but I wanted to weave my pattern directly into the cloth. Rather than using imagery from centuries past, I decided instead to make an internet culture toile using primarily images of Doge and Bob Ross. One scene depicts Bob Ross and doge as the heads of eagles with America in the background, another is of Bob Ross painting a lost doge sign, in another a humanoid doge is painting a portrait of Bob Ross, and finally an image of Lia Cook (who pioneered the use of the Jacquard Loom in art) has been altered so that Bob Ross is in her studio weaving an image of doge.
In this case, I wanted a repeat pattern. My image was pretty big, significantly bigger than it needed to be since the TC-1 only has 1760 warps, so a pattern larger than 1760 pixels wide would be silly. However, I kept it at a fairly high resolution just in case I wanted to do something different with the pattern later. To make the repeat, I increased the canvas size, doubling the height, but keeping the width the same. Then, duplicate your layer (command+J/ctrl+J). On your second layer go to filter>other>offset change each to half your canvas size (or more in the horizontal direction for greater offset. To define as a pattern, select all (command+A/ctrl+A) then go to edit>define pattern. Make a new image (File>new or command+N or ctrl+N) that's super huge, in this case 9999x9999 px because I wanted to see how it would look as a repeat. You would probably be better off just making your pattern the correct size to begin with.
Step 2: Making It Work With a TC-1
We have 1760 warps, but in this case, each warp thread alternates between white and blue. Because I wanted a white background, I decided to make a double weave that was the same on both sides of the cloth. Essentially this means that I was weaving two cloths at once by weaving first the white warps, then weaving the blue warps underneath. It's difficult to explain without trying it.
Since I was making a double weave that means there's a width of 880 on the top (half of 1760), and 880 on the bottom. I made a new image, 880px wide, and however long you want your cloth to be, in my case 1000px. Fill your new canvas with a pattern. I ended up taking part of the pattern that I filled my giant 999x image with, scaling it to fit, and placing a reasonable portion of it onto my new canvas.
There's a limited amount of variation in color that can be made. I wanted to stick with three colors, the white background, the darkest color, and something in between. Start by converting from RGB to grayscale. (Image>mode>grayscale), then convert back to RGB (image>mode>rgb), then convert to indexed color (image>mode>indexed color). By converting to grayscale first, I find I have better control of mid range colors since I'm more interested in tone than hue. After choosing the number of colors you wish to preserve, click ok and convert back to rgb (so that you can work with layers again).
With your three color image, separate each layer by color. The easiest way to do this is by using the magic wand tool with tolerance set to 1, antialias off, contiguous off, and sample all layers off. Select the white part of your image, then press command/ctrl+J to make a layer with just that selection. Go back to your original layer, select gray, and again press command/ctrl+J, select black on original layer and press command/ctrl+J. At this point, I usually hide the original layer and check to make sure each new layer is just one color.
Now it's time to give it weave structures. My three colors are going to be dependent on what weave structures I choose. In this case I'm using a warp-face satin, a weft-face sateen, and something in between. I've attached the patterns I used. To load patterns, click the paint bucket tool, then select pattern, rather than foreground at the top. Click the gear icon, then click load patterns. Alternatively, you can make and define weave structures yourself.
I want my white warp on top, so I'll fill that part with the darkest pattern (black means warp up), gray with the medium pattern, and black with the lightest pattern. See images.
Step 3: Turning It Into a Double Weave
Expand your image complete with weave structures back to 1760 px wide. Keep the setting on nearest neighbor (hard edges). We don't want any antialiasing in there. Make a copy of your image filled with weave structures.
The cloth on the back will be a mirror image of the front and we wouldn't be able to read the text if we don't flip it, so take your copy and flip it. (Image>Image rotation>flip canvas horizontal.) Paste that back onto your original image. Use the lime green pattern (2 px wide with transparency on the top right corner, and the other three filled with green) and fill a new layer. Select the lime green portion, select inverse (command+shift+I) and delete those pixels from your reversed image. Hide or delete your lime green layer. It's done it's job. Now make a new layer, fill with the white dot pattern, make a new layer fill with the black dot pattern. Refer to annotated images.
If you wanted, you could have an entirely different image on the top than the bottom. That would be pretty cool. You should do that.
Step 4: Start Weaving! (and Trouble Shoot)
You might need to do some troubleshooting. The first time around, I was packing pretty tight. I needed to go back and adjust my image (skew it) so that it wouldn't look so tightly packed. The first time I also forgot that the back would be a mirror image. Oops. So I tried again and made a mirror image, but also reversed my colors and gave the back a weft-face. It seemed like a good idea, but I wasn't thinking about how the back was actually the back of the cloth and the face of the back cloth was in the middle of the cloth-tube I was weaving.
Ultimately, I have a few broken warps anyway, so it seems unlikely that I'll use the back, even if it does look more or less the way I want it to.
Such is life. Trial and error.