Owning It

While working on a new project for my son I started thinking about patterns and modifications. If you start with a pattern and then make a lot of modifications, is there a point where you can own it and say it is your own pattern? Now don't get me wrong, I feel that credit should be given when you use a pattern or even if the pattern you created is loosely based on another. Sometimes I will see a pattern on a blog and then later see a very similar pattern somewhere else but with a different designer. I just wonder where do you draw the line? (click for bigger)

The Spin-Off pattern seen here (scroll down a bit) uses a lighter weight wool than I had spun, so I had to change the stitch count and needle size. After changing the colorwork pattern also I basically ended up using only the cast on method and the 3-needle bind off but even did that with a twist as I ended up adding fringe while I cast off. But I still think that credit should be given to the original designer because I doubt that I would have come up with this litle bag on my own.

Project Specs:
Pattern: Based on Deborah Pullman's Gunnister Man's Pouch pattern in the Summer 2006 issue of Spin-Off
Yarn: My own handspun. Light grey Romney (gifted to me by my friend Madame Purl), dark gray Shetland and then some blue Wensleydale, all around sport weight. Approx. 100 yards romney, 35 yards shetland, small amount of wensleydale.
Needles: Knitpicks Options, size 4
Started: 1/16/07 Finished: 1/20/07