|My patterns, enlarged and altered|
So here's the method that I use, though not the only one. I find this is pretty fast and painless. I enlarge in Photoshop or Gimp (I actually prefer Gimp for this even though I have both). There's a couple of tricks I've developed that help with this. Here's my process:
I scan the image into my computer and open it up with the pattern editing software. If I am dealing with many pieces, I isolate one pattern piece by cropping the rest out. Then I set the canvas size to 8 1/2" by 11" which is the size of my paper I am going to print on. Then I enlarge the image 800% (when the scale is 1/8" = 1"). The pattern piece is then larger than the canvas. I move the pattern around saving each 8 1/5" by 11" piece to my computer. Now when I have a large piece that has a basic shape or has a long straight line, it can get confusing when taping everything together to determine where exactly they match up. So I, with my pencil tool, draw little squiggly lines on the seam between two pieces. That way, it is possible to match the squiggly lines up when taping. The more squiggly line you draw the more accurately you can line everything up. Finally print everything out, match up the squiggly lines, tape everything together, and alter the pattern as needed.