darktable-org/darktable — pull request #707 by mgehre (2014-10-20 20:33:26+00:00)
Title: Generate MIPMAP from larger MIPMAP if available

Whenever a MIPMAP must be generated, we first check if there is a bigger MIPMAP available which we can use by scaling down. This saves the work to load the raw file and apply the pixel pipeline.