Picture Medley provides a few tricks to help tiles match the target image a little more closely. All of these tweaks are done to the tiles without any prior knowledge of how they might be used in the final Medley. Each of these techniques creates additional virtual copies of tiles, but every effort is still made to avoid tiles appearing more than once in the final Medley.
By default, the software will only use the largest possible square region from the center of the source image. If you select the "Tile Portions" option in "Tile Tweaks", additional smaller squares will be taken from the same source image, and enlarged so that all tiles are the same size. This is illustrated below.
Let's say that the image shown in Figure 2 is among the Source Images selected for this medley.
Figure 3 shows the regions that are available for medley tiles.
Figure 4 shows the primary crop, used by default. Figure 5 shows the secondary crops, used if "Re-use Tile Portions" is selected.
The Medley technique works best with a large assortment of images. If you don't have enough images to populate each tile location uniquely, the software will give you the opportunity to repeat tiles as needed to fill the medley. Re-using tile portions is a useful way to help the repeated tiles be slightly different from each other, which will improve the perceptual quality of the final output.