Dear TIG
I'm e new with Sketchup and i have typical problems which are similar as pngwhite2transparent. I was update the SKM tools loader and extracted it in my installation of program. I was done everything like in the post, but i don't know how it works. In the post:
http://forums.sketchucation.com/viewtopic.php?t=34383 is instruction how to install his plugin:

Loaded by SKMtools.rb in the ../Plugins/ folder.
Adds a new tool:
pngwhite2transparent(folder_of_pngs)
It needs PNGwhite2transparent.jar in the same folder.
To use it type in the Ruby Console
pngwhite2transparent 'C:/Temp/MyPNGsFolder'
It makes a new folder
C:/Temp/MyPNGsFolder/PNGwhite2transparent
which will receive copies of all pf the PNG files in the folder.
These PNG file copies are processed so 'pure white' pixels [255,255,255]
are all made 'fully transparent'.
If opens this new folder on completion.
It also returns the path to this new folder [or 'nil'].
For example: ensure your scenes have a pure white background, then export
them as an animation as multiple individual PNG files, this tool then
allows you to remove the backgrounds - then in any 'animation' you
assemble [e.g. GIF] you have a 'see-through' background...

But in my program it doesn’t work, I thought that in sketchup it adds new plugin SKMTool, but not. So I will be very grateful if you can explain how to make my pictures.png without shadows and edges:
http://www.imagic.pl/files//18736/./zdjecie2.jpg

Best withes
rusalkas