Or faster, smaller and better at keeping metadata together than ImageMagick: IJG's jpegtran. This has the advantage of preserving the luminance channel exactly, whereas IM is likely to decompress, greyscale, then recompress the image.

--
bowling trophy thieves, die!

In reply to Re: Re: converting Jpeg to grayscale by Willard B. Trophy
in thread converting Jpeg to grayscale by Anonymous Monk

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