The collage mode
This mode mixes up your favorite albums and pastes them on the canvas at random locations. Edges are smoothed out and some transparency gives an overall rather pleasing effect:
The collage has 5 parameters but you'll probably only need to know about the first two: album size and passes.
For my own desktop wallpaper, I use ./wallpaperfm.py -m collage --CanvasSize 1400x1200 --AlbumNumber 100 --GradientSize 10 --AlbumOpacity 90
The album size is 250 pixels by default, this is good for a 1280x1024 image but you might want to use something smaller if your final image is small. Use '-a' or '--AlbumSize' to change that. Ex.: ./wallpaperfm.py -a 200
Your profile contains a maximum of 50 albums and since the covers are placed randomly on the screen, it's quite likely that there'll be some empty spots every now and again. To get round that, the script runs a few times over, which reduces the probability of empty spots. The default number of passes is 4, and you change it with '-p' or '--Passes'.
You can change the default number of albums used in the collage (50) to something else with '-n' or '--AlbumSize'. It has a maximum value of 200.
Album opacity and gradient size
A mask is applied to each picture before pasting it onto the canvas. The mask is black on the edges gradually reaches a maximum value towards the centre. This maximum value is set by the album opacity. It's a number between 0 and 100, with 100 meaning that the centre of the cover is completely opaque (i.e. we can't see through.). You can control it with '-o' or '--AlbumOpacity'. The default is 90.
The portion of the image that's in the gradient is set by the gradient size. It's a percentage of the picture, between 0 and 100. The default is 15 and you control it with '-g' or '--GradientSize'.
For your information, here is what the mask looks like for a 200x200 picture, with a GradientSize of 20 and an AlbumOpacity of 70 and its effect on a picture: