Re: [LUG] Bulk image conversion

[Gordon Henderson <gordon+dcglug@xxxxxxxxxx>]

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

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