Resizing images in Gimp and Darktable

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    • #11609
      Adrian Midgley

        Gimp is the GNU Image Manipulation Program. It has been around for quite a while, and is now quite good, if a little sprawling.

        Darktable is a more recent, perhaps more modern, approach to photograph editing.


        Usually one wishes to reduce the size, as in the number of pixels, of an image, as a last stage  of editing, or opens an edited file to produce a smaller one for display by projection or on screen.



        With the image open select the image menu, scale image, choose pixels as the option and give it the limiting number for height or width. By default the other number will be reduced to match.

        Probably reduce your number, now, by 2 or 4 pixels for a single or double edge.

        Click the button, and it is done.

        File: Export to export your scaled file, give it, usually, a name varied from the original – I append sRGB-1600 for a file for the screen which will be (is) 1600px in its longest, limiting, dimension.  The type of file, which will be JPEG, is set by adding the right file extension, .JPG to the name.


        You want a border.

        To be continued



      • #11610
        Adrian Midgley

          Gimp is provided wwith various filters, including sharpening and adding a border.

          Filters: Enhance: Add border.

          The default is blue and wide, I don’t know why.

          Set the options to, if you are me, 1 pixel wide, and click the colour to select from the usual colour diagram. White in this case. These settings persist for the session if not altered. I leave it on 25% opacity.

          Click the button and it is made so.

          Go back to Filters: and show the border ond again. Choose black, or use the dropper in that dialogue to pick a dark colour from the image. Probably nobody would notice.

          You now have 3 layers, the top two are the borders, the one below is your image.

          Having shrunk the image, you may wish to sharpen all or some of it for the final size. Do so in the usual ways.

          Then merge or flatten the whole lot, and export it.



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