How to make a projection screen that's also a painting

Step 5 Bring in the Gimp

Before putting on the outer frame you should paint the edges so the part where the outer frame meets the painting looks as good as possible. But in order to do that you have to know what you're going to paint. So you start out by finding a nice motive. Things to keep in mind at this stage is to pick an image that will look good in only two colors. This means avoiding images with lots of clutter and small details. I knew I wanted to make the painting film themed and looked at a lot of Bogart pictures, sadly almost all of them were too cluttered to work and since Steve McQueen is the coolest thing ever to walk around in a pair of pants I finally settled for scenes from Bullitt.

So with that we turn to Gimp (I'm sure a number of other applications will do just as well, but the examples will be in Gimp). First off we convert the image into greyscale (Image->Mode->Greyscale), then we erase the details we aren't interested in, this makes the following step somewhat easier. The next step is the Threshold tool (Tools->Color tools->Threshold) where you can fiddle with the detail level until you're satisfied.

Before moving to the next step we need to make sure that the white parts of the image are transparent rather than white (they probably aren't). Easiest is to go back to RGB, add a background layer and flood fill it with some other color and make sure that there is an alpha channel present (Layer->Transparency->Add Alpha Channel). Then use the wand (actually, "Fuzzy Select" is the proper name) tool and start selecting all the white parts and delete them (zoom in to get the smallest parts).

If the image is small, now is a good time to make it the intended size before applying the Oilify filter (Filters->Artistic->Oilify). Before oilifying the image will be rather "prickly" but the oilifying takes care of that and the end result looks really professional.