|The source file - from which we will get our placeholder tiles.|
|The slice tool is hidden under the crop tool, what you want is the "Slice Select Tool"|
|The divide slice dialog blocks lets you choose how to break up the source image|
The "Divide Slice" dialog box lets you choose how many slices on the vertical and how many on the horizontal, since we know there are 3 x 3 tiles here, we can just choose 3 for both axis. Once that's done the source image will update in realtime and show the slices we've just asked for. Crisp perfectly deliminated tiles of 32 by 32 pixels.
The final step is saving out the tiles as separate images, I do this by choosing Save for Web and Devices.
|Save for Web and Devices Dialog|
|Save dialog with option for saving out all slices.|
|All 9 tiles ... only the first is PNG because I didn't select *all* the slices in the Save for Web and Devices dialog - doh!|