also convert/pngcrush png pictures with 16bit/channel (resulting in 8bit/channel) and repage their layers (as I found out that some of the pics had their layer offset the actual visual area, which makes the picture look blank in gimp)

Art
Bamboo
Bath
Brick
Castle
Cheese
Christmas
City
Compost
Desert
EarthRise
Freeway
Halloween
Hell
Island
Jungle
Nature
Olympics
Sheep
Snow
Stage
Underwater