GIMP has 6 different ways to select parts of an image, and they all have their own niche and utility. Here’s a quick guide to using each one effectively.
After you’ve made your selection, you can add to it with any of the select tools by holding the Shift key, and take away from it by holding the CTRL key while you use the tool.
You can invert, de-select, or select all by Right-Clicking>Select>One of those functions.
Press the Enter Key after you have drawn your selections unless otherwise stated.
Switching tools BEFORE pressing Enter will CLEAR your drawing, and it cannot be recovered. You can, however, switch tools AFTER you have confirmed the selection (the outline is animating).
Recangle and Ellipse Select Tool
The Rectangle Select Tool allows you to make a selection in a square or rectangular shape, and the Ellipse tool does the same but in a circle.
Lasso Select Tool
This tool allows you to click and drag around the image to select freely using the mouse. You can also select by points around the image, connect by straight lines.
Fuzzy Select and Select By Color Tools
The Fuzzy Select (Magic Wand) tool selects an area of an image based on color similarity. You can adjust the threshold to increase how much of a difference in RGB values a pixel can have and be recognized as “similar” to the selected pixel, with the max value of 255 selecting the entire image.
The Select By Colors tool does the same thing but for the entire image, instead of just an area. Every pixel on the image that is within the threshold becomes selected. These tools are good for adding Backgrounds to images or adjusting color values across the board.
Intelligent Scissors Tool
This tool connects points by a line that snaps to pixels of similar RGB values, attempting to create an outline. It snaps points to certain parts of the image as well, making this tool a little frustrating to use. selections can be jagged and should be smoothed out with other tools, but it can do most of the work of selecting for you. This tool is good for separating objects from images, creating cardboard cutouts.