[QUOTE="Dave Martindale"]\n[email][/email] writes: [/QUOTE]\n[QUOTE]\nHuh? If you select 6 MP output, there was nothing lost in the rotation.\nIf you select 3 MP output, you *did* lose information in the rotation,\nbecause the output format doesn't have the pixel density to retain the\ninformation. You can't "add it back" while remaining at 3 MP.[/QUOTE]\n\nConsider the 3M diagonal image, rotated and resampled to 3M\nrectangular co-ordinates. If you take the FFT of the resampled image,\nthere is no high-frequency information -\- as you say above, it's been\nlost in the resampling. So, there is an opportunity to encode some\ndata there. And the data you could put there is the difference\nbetween the original filtered at FS/(sqrt 2) and the original. By\ndefinition, that result contains no low frequency information.\n\nAndrew.