Computer fonts can look unattractive at larger sizes; as the letters are expanded, the edges may appear jagged. This is called "aliasing." If you are using GIMP (GNU Image Manipulation Program) to add a large caption to a photo, smooth the edges of the letters by using the "antialiasing" function. This function adds extra colouring to the corners of letters, making them appear smooth in large font sizes.
Launch GIMP from the Start menu or desktop shortcut and open the image to which you would like to add a caption. If you have already added a caption to the image and have not merged the layers of the image yet, GIMP displays the caption in the "Layers" window. If you do not see the "Layers" window, open the "Windows" menu at the top of the screen, and then click "Dockable Dialogs" and "Layers."
Click the entry in the "Layers" window for the caption that you have added to the image. If you have not added a caption yet, click the "Text Tool" button in the "Toolbox" window or press the "A" key on the keyboard.
Click the "Antialiasing" check box in the bottom half of the "Toolbox" window to smooth the edges of the caption. If you have already added the caption to the image, GIMP smooths the edges of the letters automatically. If you have not added the caption yet, click the image, type the caption that you want to add and click "Close."
If you have added a caption to an image and saved it as a merged image with only one layer, you cannot enable antialiasing for the caption as it is no longer possible to modify the caption as an independent layer.