You can open existing images (any file format supported by Maya) onto the canvas, then paint on them. For information on the file formats supported by Maya, see Supported file formats.
You can also use Paint Effects to modify existing textures.
To paint on an existing image
Click Open (Windows and Mac OS X) or Open Image (Linux).
Click Yes to save the existing image.
The Save Image (Linux) or Save (Windows and Mac OS X) window opens. Type a name for the image, including the file extension (for example, forest.iff) and click Save Image (Linux) or Save (Windows and Mac OS X).
Click No to clear the canvas without saving, then open the imported image.
To paint on an existing texture
Click Yes to save the existing image. The Save Image (Linux) or Save (Windows and Mac OS X) window opens. Type a name for the image, including the file extension (for example, forest.iff) and click Save Image (Linux) or Save (Windows and Mac OS X).
Click No to clear the canvas without saving, then open the imported image.