In the comments to my Stripes! post, several of you asked about how I used the barcode to calculate the stripes for my warp. It's possible to just visually guesstimate the relative width of the stripes, but for those of you who, like me, want to be a bit more accurate, I'll show you how I did it.
The easiest way is to apply a grid to the barcode. I did this by opening the barcode image in my photo editor (GIMP), and adding a grid (View > Show Grid). I had to try several different grid sizes to get the bars to fit.
Any grid can give you an approximate idea of the relative width of the stripes, even if they don't fit the grid exactly. To get an accurate measurement, I found that the best grid size was one pixel.
This meant that I had to zoom the image 800% to see the grid. As you can see however, that's a lot of pixels to count! Being the lazy/impatient sort, I decided to try resizing the image. In the photo above, the narrowest stripe is three grid units wide. To simplify counting, I resized the entire image to about 1/3 the original size.
My narrowest stripes were now one grid unit wide, and the widest were six. Much easier to count. I ran the barcode off on my printer, and wrote the down the number of units on the printout as I counted them.
The next step was deciding how many warp ends to make each unit. To get the required 18 inch width for the towel, I needed 702 ends for waffle weave in 10/2 cotton, sett at 30 epi. I had a total of 112 units in the barcode, not counting borders. By dividing 702 by 112, I discovered that I could make each unit six warp ends wide and have some leftover for borders. That means that my narrowest stripes are six ends, and the widest stripes are 24 ends.
In reality, as I've written this out, I have realized that I made some mistakes when I counted the units. But! When visually comparing my warp to the barcode, no one will know. Which goes back to visually guesstimating, which would work well too. After all, if we don't point out our errors, very few folks will see them on their own.
Obviously this would be a whole lot easier for knitted stripes. For weaving it just took a little more counting and calculating.
Does this make sense? If you have any more questions, just let me know. And let me know when you post photos of your barcode projects!
Posted 7 Aug 2008 at http://leighsfiberjournal.blogspot.com