Hi, I like to buy Sudoku magazines (the 'killer' variety with the
grids inside), scan the puzzles into jpgs, and them print them much
bigger. The only way I get a decent image is to scan them grayscale,
which leaves much of the backgrounds grey (surprise surprise). I am
getting through quite a few ink cartridges printing these things out,
and thought that even a newby like me ought to be able to use CS3 to
remove the gray, and leave just the black grid/numbers.

It seems to me that using CS3 for such a mundane task is like using a
chainsaw to cut down a dandelion; i.e. it is far too powerful a beast,
because i have tried many different techniques (boosting contrast/
brightness, painting white etc), but have so far failed to find a
slick method to do what i want. Given that there are roughly 50
puzzles per mag, I was hoping for something very simple.

Can anyone out there ?