Thus, this function creates a selection of the border around the previous selection's edge. This command is a combination of the two functions Shrink and Grow . The width of the border is specified by the border dialog. Note that the dialog contains a menu that allows the border width to be specified in a variety of different units. The default unit is pixels.
Border is particularly useful for refining selection edges.
The Save to Channel Function Channels were introduced in Section 2.2 . This channel shows a thumbnail of the mask representing the selection. Much more on the subject of masks and selections is discussed in Chapter 4 . The difference, however, is that the selected pixels are not obtained by growing a contiguous region around the seed. The By Color selection tool selects all the pixels in the layer that are within a specified threshold of the seed pixel's color.