Monday, February 8, 2010

Drawing hollow circles on pictures using GIMP

I rarely use the image editing tool automatically available in most flavors of Linux but I wanted to draw a circle on a photograph. Trying to figure out how to do this was tricky; GIMP is very powerful but it takes some real know-how and not just fiddling around to achieve specific results. It is a fun way to waste time and to see what crazy things you can do with a photo. Yet I figured, "How hard can it be to just draw a circle?"

Very hard, it turns out. I don't have a steady enough hand to draw a perfect circle using a mouse. So I tried the ellipse selection tool but was completely stumped on how to make the shimmering ellipse into a real circle with color. So it's off to Google to find instructions.
I tried all kinds of search terms - "circle" just told me how to make filled in circles; "bubble" told me how to make speech bubbles but were still filled in circles; "hollow" anything didn't help. I finally got help with "circle outline" from http://hubpages.com/hub/Creating-a-Rectangle-or-Rounded-Rectangle-Using-The-Gimp. And after I successfully created my circle thingy on my fail blog submission, I decided these instructions needed to be easier to find for anyone else who uses GIMP infrequently. Here is a quick guide for making a simple hollow circle.

*Note: Many mistakes can be undone by pressing ctrl + x. Deleting the layer will erase all the editing. If you're really stuck, try exiting Gimp without saving.*

1. Create a layer (Layer -> New Layer). For this task there's no need to adjust the layer settings but it would help to name the layer to something easy to recognize, such as "Circle." Having a layer will make it easy to delete any bad circles by just deleting the layer. Think of it like putting a sheet of glass over your image.
2. Click on the ellipse select tool in the toolbox (second from left in the top row).
3. Inside the image, drag the mouse to have the shimmering ellipse tool covering the desired area on the image - you can adjust the boundaries by hovering over any corner until the cursor becomes L-shaped and then dragging to resize.
4. Before you actually draw a line, click on the foreground color box in the toolbox to change it to whatever color you want the circle line to be.
5. Go to (Edit -> Stroke selection).
6. Here's where my instructions really differ from the link's. Leave it selected to "Stroke Line"; this allows you to decide how thick the line is (I find 15 to 20 pixels to be a good width).
7. Your hollow circle/ring/bubble should be visible on the photo!
8. If you try to leave it at that and save, you'll get error messages and it will ask to export. To avoid this, go to (Image -> Flatten Image). Carrying the glass sheet overlay metaphor further, flattening will seal or put anything that's on the layer right onto the image. You will now be able to save the image without the error messages or having to export anything.

I hope these instructions helped. Feel free to let me know if you have any questions or comments.

2 comments:

Aidan said...

Thanks, this is exactly what I was looking for.

I was trying to outline specific parts of a screenshot for some documentation and got stuck - who'd thought it would take this many steps to draw a circle?

Aidan said...

Thanks, this is exactly what I was looking for.

I was trying to outline specific parts of a screenshot for some documentation and got stuck - who'd thought it would take this many steps to draw a circle?