2012-01-05 23:05:09 UTC
maketx 256.tif --mipimage 128.tif --mipimage 64.tif -o out.tx
This makes the first there mip levels 256.tif, 128.tif, and 64.tif. Levels thereafter will continue to downsample the last one specified (64.tif, in this case).
I did this a while back in order to make a special debugging MIPmap. Sat in my tree for a long time, I just remembered I should have it reviewed and merged.
lg at larrygritz.com