Unfortunately this issue persists on the Google Docs end and there isn’t an immediate solution. You could try reducing the color depth of your documents – using a lower setting (or simpler images) the images may appear more grainy but less outright incorrect.
Due to Google’s negligence on this issue (and some others) you might expect this issue not to be fixed anytime soon. But then I did wake up one morning and find the long-standing issue of nonworking hyperlinks fixed, so one never knows. It would seem at the moment though this issue isn’t of great importance to them…
