Knitting-Guy is correct. You have also stated the design inspired you which the original designer could (I say 'could') jump on.
*A colour change does not change a design copyright.
*If the original design can be basically 'seen' albeit a few stitch changes exist, the original copyright still exists on the item.
*You could only write out an 'inspired by' pattern IF the original designer agrees.
*You could only make and give to friends if the original copyright allows that OR, as I suggested in the other thread, each friend buys a pattern (original) also.