The retouching tools have the following similarities and differences:
Clone stamp tool: As you paint, the tool duplicates the pixels from another area of the image. You set the sample area by holding down Alt (Windows) or Option (Mac OS) and clicking the clone stamp tool.
Pattern stamp tool (Photoshop only): As you paint, the tool lays down pixels based on a pattern that you designate. You can create this pattern from an area of the current image, from another image file, or from the default set provided with Adobe Photoshop 7.0.
Healing brush tool (Photoshop only): This tool works like the clone stamp tool except that Photoshop calculates a blending of the sample pixels and the painting area, so that the restoration is especially subtle yet effective.
Patch tool (Photoshop only): This tool works like the healing brush tool except that instead of using brush strokes to paint from a designated area, you drag a marquee around the area and then drag the marquee over another area to mend the flawed area.
History brush tool: This tool works like the clone stamp tool except that it paints pixels from a designated previous state or snapshot that you select in the History palette.
A snapshot is a temporary record of a specific stage in your work session. The History palette saves only a limited number of steps. After that, each new step you perform removes the earliest step from the History palette. However, if you take a snapshot of your work at any available step and then continue working, you can revert to that phase later by selecting the snapshot in the History palette, regardless of how many steps you’ve done in the meantime. You can save multiple snapshots, as needed.
The Aligned option governs the relationship between the sample site and the brush. The difference between selecting or not selecting the Aligned option is significant only if you use multiple strokes as you retouch—that is, if you change the position of the pointer between brush strokes.
If Aligned is selected, then the sampling crosshairs go back to the original sample site each time you start a new brush stroke.
If Aligned is not selected, then the sampling crosshairs maintain the same relative position to the brush as when you started the first brush stroke, so that an imaginary line between the brush and the crosshairs would always have the same length and direction.
The patterns you create and save in the Photoshop Pattern Maker dialog box are saved with the application. Even if you close the current file, switch to another project, quit Photoshop, or reset your Photoshop preferences, that pattern will still be available in the pattern picker. (However, you can actively remove patterns, which deletes the pattern permanently.) Snapshots are deleted when you close the image file and cannot be recovered in later work sessions on that file. Snapshots are available only in the image file in which you created them.
