You can knit any pattern or picture into a background. The method you use is intarsia. You'll also need a chart of the picture you want to copy. Each box on a graph-paper chart would be a stitch. There are instructions here in the videos and in many books.
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo!! --Hedgehog
IngridKH on Ravelry