I edited this question to make it more general and to be more clear about what the OP was asking. I also edited it so that I can provide a brief overview of what rate distortion theory is and to answer the question in detail. My edit was approved, but the question wasn't re-opened. I've already prepared a detailed answer, but I can't post it since the question wasn't re-opened. I also don't want to post a similar question with my own answer to avoid a duplicate.