thanks - I tried your solution already - good results - but if you have a portrait to convert - how can you determine only that part of the picture where the tiles should be used? If you have a portrait to convert you ONLY want the face itself to be converted, the background should remain unchanged. Is this possible too?
What should remain unchanged? The background of the final mosaic or the background of each face tile?
A) If you want the background of the mosaic to be equal to the original image or whatever else then use a free Paint program to cut out the face / background and merge the final mosaic with another image you want. I suggest Paint.NET or GIMP software.
You can do that also with AndreaMosaic, but you must specify a MaskFile that defines each tile of your mosaic, and so you can create even irregular tiles and leave some background unchanged. See the user manual for more details.
B) If you want that the backgound of each tile is unchanged (only face of each tile should change colors) then it's more complicated. Much more complicated. A solution is to do modify the face tiles manually before adding them to AndreaMosaic Tile Collection. Create some different copies of your face tile, and modify only the face. Then say to AndreaMosaic to not change the tiles at all.
Since you are using the same face tile, another solution is to create two different mosaics. One where you allow to change the face tile. Another one where you give as input a new face tile made with only two colors, a white background and a black face (and set ColorChange to 0%). So the final mosaic will be a black/white image that you can use as a selection to cut out the background like in solution A).
Hope this helps....