Ubuntu :: Cp Not Dealing With Variable Properly?

I am having trouble with a script that is supposed to : a)take all the jpg pictures in a given directory/parameter and create thumbnails of it in a directory on the desktop.

e.g
from /here/are/the/files.jpg to ~/Desktop/parser-the/files.png. this is my script: all the individual parts work but it falls apart when i put them together.

Code:
for picturesource in $(ls ${1}/*.[jJ][pP][gG])
do
echo this is the picturesource $picturesource;
destination=~/Desktop/parser-"${picturesource}";
echo this is the destination $destination;

[Code]...