![]() ![]() That is, an additional pixel between black-and-white original pixels will get a gray color. This means that when you add new pixels to an image, as you must when you make it larger, a process called interpolation will calculate the color and value of the new pixels based on the properties of the neighbor pixels. When you enlarge your image with Scale, Gimp interpolates the new image. If you uncheck Constrain Ratio and then change the proportions, Scale will stretch or compress the image to fit the new size, thus distorting the image. If you check the Constrain Ratio checkbox, the proportions of the old image will be kept. Scale makes everything in your image larger or smaller, including layers. Right-click|Image| Scale changes the size and aspect ratio of your image. If you uncheck Constrain Ratio and then change the proportions, Resize will either crop or add a transparent area to the image to fit the new size. If you check the Constrain Ratio checkbox, the proportions of the old canvas will be kept. Set where on the canvas you want to place the image by dragging at the gray "image rectangle" in the dialog window, or by specifying a value in the X Offset and Y Offset fields. The dialog box displays a preview of what the proposed changes in size, aspect ratio or offset will look like. To resize an old layer, use the Resize Layer option in the Layers menu you get from right-clicking in the Layers tab ( right-click|Layers| Layers and Channels|| Resize Layer). You find that your layers are too small to contain things you want to add to them, or perhaps you wish to change the shape (aspect ratio) of your image without distorting the information within it. The old layers, however, will remain as before.ī. When you resize the canvas, all new layers that you create will have this size and aspect ratio, unless you specify another width and height in the New Layer dialog box. You're happy with the layers you have, but you need a new canvas size to make space for new and larger layers. There are basically two reasons for changing the canvas size:Ī. The scale and aspect ratio of the actual image and the layers within it are not affected. The right-click|Image| Resize command is used to change the size and aspect ratio of the "canvas" where your image is placed. If you are doing web design, you should use the The Enable Floyd-Steinberg dithering option helps to make indexed images look "good" even if they only include a few colors. To set the number of colors, press the Generate optimal palette radio button and type the number of colors you want into the # of colors box. In general, however, you are free to specify any number of colors for an indexed image. When you think of indexed images, you probably think about GIF images with a maximum of 256 colors. This will open the Indexed Color Conversion dialog box. Select the right-click|Image| Indexed command to convert an RGB or grayscale image to indexed. If you are using an indexed image, convert it to RGB immediately, and don't convert it back to indexed until you're finished with it! For more information on RGB, grayscale and indexed images, review "Color Models" starting on page 189. Most commands, filters and Script-Fus give poor results or no result at all when used on indexed images. Tip: All color information is irreversibly lost as soon as you convert to Grayscale, and a lot of color information is lost when converting to indexed. Some commands, filters and Script-Fus require grayscales, whereas others require RGB images. If you know that you want a grayscale or indexed image, you can easily convert your image later. Normally, you'll work on an image in RGB color. Right-click|Image| RGB, right-click|Image| Grayscale and right-click|Image| Indexed are the three conversion options you have for your image. The Colors, Channel Ops and Alpha submenus will be covered in separate chapters. ![]() In this chapter, we're going to discuss what you can do within the image menu. The Image menu offers some of the most useful image manipulating functions in Gimp. ![]()
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