Ravelry project page: Holiday Sanity Scrapghan
When the point is to use up what I've already got, not to buy more yarn, realizing that I'm going to run out of the two shades of pink being used for the final rounds of each square means figuring out what color I've got on hand that will work instead.
I'm working with a fairly small color palette, and I'm not too worried about the final results, but I'd like there to be some consistent elements to tie it together visually. The squares are all the same size and worked at the same gauge, so that's a start, and all of the squares have at least one of the two shades of pink that are being used, and again, in the final round it's one of the two. I'm now at a point where if I keep using them for the final round, I won't have enough. If I use a yarn of the same color value (or very close to the same value), that could help keep the overall blanket looking consistent. It could even be an improvement, breaking up the lines in an interesting way without looking chaotic.
There are a number of ways to determine value; what I've done here is taken photos and then compared them to copies in gray scale (PicMonkey is a simple, free program for photo editing - used it for converting photos to gray scale and then collaging them together for easy side-by-side comparison). If you want to be really accurate about sorting and matching color values, there are tools you can use, like The Ruby Beholder or the Gray Scale and Value Finder, and for planning out color schemes, the Color Scheme Designer is a fun, free online tool. None of this is cheating: these are useful tools to help you make choices, and are used by industry professionals. I have an art degree and no shame about using them; I hear people saying "oh but I'm no good at picking out colors" and want to sit them down with the Color Scheme Designer immediately. We're not all color geniuses, and we don't have to be.
I may be able to work up another color for the border rounds, using leftover white yarn and experimenting with dyes I have on hand or can make using plant material.
For more details about color theory, there are a lot of great resources out there. Here's just a few:
Suzyn's Color Theory for Knitters (Knitty, Fall 2004)
Color Theory Basics for Knitting and Crocheting (Lion Brand Yarn Blog)
Exploring Colors for Your Knitting (Craftsy blog)
Color Journey: a mini-course on creating color you love (Dyeing to Knit blog)