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On Fri, 2010-01-29 at 15:16 +0000, Gordon Henderson wrote: > On Fri, 29 Jan 2010, Keith Abraham wrote: > > > > > I have a directory containing approx 100 colour images (.PNG) which I need to > > convert to grayscale. > > > > I could convert each one individually using GIMP but I'm sure there must be a > > tool to do a bulk conversion. > > Anyone know of such a tool (imagemagick?) and how to do the conversion? > > You said it yourself: imagemagick - specifally the mogrify tool. > > So start with > > man mogrify > > and take it from there. > > Take a copy first, as mogrify changes file in-place! > > > However, converting from colour to greyscale is a bit of a black art, > depending on how "nice" you want it to be. There is a nice way to do it in > GIMP, but it requires a few stages (rather than just pushing the greyscale > button), but it all depends on how you want to capture contrasts, etc. > > I use csh, so for me, I'd do: (on the copy!) > > foreach f (*.png) > echo doing $f > mogrify -type Grayscale $f > end > > I'm sure someone who knows bash can give the equivalent. > > Gordon > I realise this isn't a neat and tidy command line solution, but digikam the photo management app has a grey scale bulk conversion option - under tools/colours. It doesn't seem to give you many options as to changing the grey scale, but it will rename all the images and save originals etc. It also has many other useful batch conversion tools. It is a kde application, but will happily run on gnome, although a distro with a repo manager that picks up all dependencies is helpful. kipi plugins should be installed at the same time. IMHO digikam is by far and away the best photo management/album tool around. Better than commercial counterparts for other OS's and better than f-spot its OSS counterpart for gnome. f-spot doesn't have the range of basic photo editing options, or the batch processing options. f-spot also has a confusing directory storage structure which makes finding a pic difficult if you're not using f-spot. Picassa is OK, but doesn't have the editing/batch options and also seems to pick up every image on your hard drive and networked machines rather than those in a designated ../Photos/etc.... directory structure. Simon -- The Mailing List for the Devon & Cornwall LUG http://mailman.dclug.org.uk/listinfo/list FAQ: http://www.dcglug.org.uk/linux_adm/list-faq.html