NOTICE: I have posted a new tutorial explaining the basics of layer masks. Check it out here.
Here is a way to use layer masks and the paths tool to merge parts of two photos into one composite image. We’ll start by taking two photos of a television, using a tripod to keep the position of the camera exactly the same. We won’t use a flash, so the first photo will have a slower shutter speed to get the correct exposure on everything around the TV. However, this makes the image showing on the TV way overexposed and blown out. So we’ll take a second photo with a much faster shutter speed to get the correct exposure on the screen.
Today’s lesson is about using the paths tool. There are a couple of different uses for the paths tool, but today we’re going to use it to make a selection. What’s great about this tool is that you can make very precise adjustments to select just the parts of an image that you need. The process does take a little time, but the end result is worth it.
Download the files used in the video tutorial if you want to follow along:
You can choose the paths tool by pressing “B” in Gimp. Zoom in to an area of the image that you want to select. Start by clicking once on the edge of the area you want to select. Move around whatever it is you want to select, making a “connect the dots” kind of pattern. You don’t have to get really detailed at this time. Just place dots at points where the shape changes direction significantly. Once you get back around to the first dot you made to start the path, hold down the Control key and click on that first dot. This will connect the last dot to the first, giving you a closed shape.
Now you can make adjustments to the selection to get in those little nooks and crannies. Each dot (often called an “anchor point”) around the selection has handlebars on it, and those handlebars are used to adjust the lines between the dots. But the handlebars don’t show up automatically. To make the handlebars show up, click on one of the dots. Then hold down the Control key and click-and-drag on the dot. A handlebar should follow your mouse. Now you can move the handlebar to make the lines go where you want them. There are two handlebars on each dot. Hold down the Control key and click-and-drag on the dot again to get the other handlebar.
If you have drawn a selection and wish you had an extra dot between two others, you can add one by holding down the Control key and clicking on a line between two dots. When you add the new dot, handlebars should automatically show up on the new anchor point.
Once you have made all the adjustments and you’re happy with the shape, you still need to convert the “path” to a selection. Do this by clicking on the Select menu, and choose “From Path.” The quick key to do this is Shift+V. Or you can click “Selection from path” in the toolbox.
Now if you use a filter or adjust colors or brightness or contrast, those adjustments will affect only the area inside your selection. You can also cut, copy and paste with this selection. The power is in your hands!
I love getting comments, so please leave some for me. If you have any ideas for a tutorial you’d like to see, leave a comment and I’ll do my best to make one for you.
