How to highlight text using The GIMP

This is ridiculously awful.

Think of buying a yellow highlighter and then using it. That’s all I wanted to do, but digitally. There are features in other programs where you can highlight text or an area; my freaking email client has this feature, with drag-and-paint, too.

But in The GIMP, it is a simple six step task with at least one “gotcha”.

Google offers gobs of YouTube videos about The GIMP, but trying to find this simple “how do I put a yellow highlight on an image using gimp” shows me pretty much anything but. There is one result new the top, but it is about using the text tool, typing text in, and “selecting” the text within it. I have an image I need to highlight some text on; but the image and text are pixels within the graphic image.

Enough blather!

  1. Open the original image and convert to RGB mode.
    1. Image –> Mode –> RGB
    2. This was the “gotcha”: What I had done was converted a PDF to PNG, and the PDF was generated in grayscale. When I was trying to do color fills (yellow is a color) with the Bucket Fill tool, the color picker had these weird corners in pink or magenta. Nothing on screen gave me any indication why those weird corners were there. Whenever I did actually do a fill, it was filling with white (apparently grayscale yellow is white) which was what the background was – so it looked like every click was useless. FML
  2. Create a new blank layer
    1. Ctrl-Shift-N is the keystroke for doing this, although I use Ctrl-L to open the Layer dialog box and click the button at the bottom to add a new layer.
  3. Use the selection tool of your choice to create the area you are going to fill with the highlight color.
    1. I do like the fact that the rectangle select tool lets me specify rounded corners.
  4. Change the foreground color to what you want. BTW, HTML yellow is ffff00#
  5. Use the Bucket Fill tool to click inside the area selection.
    1. Note that at this point, your highlight has obliterated the image underneath. Proceed to the next step.
  6. Change the layer to show the image underneath.
    1. For me, the best was to change the layer from mode “Normal” to mode “Darken only”.
      1. I suppose if your background was black instead of white, the mode would be “Lighten only”.
    1. I’ve seen a suggestion to change opacity on the layer to 30%, but that put the black text in yellow too.

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