Editing jpg's

not sure if this is the right place for this question because it has been a while since I last used this site but here it goes.

I have an idea for a simple game but it will require me to be able to edit the colour of pixels in a jpg at runtime, my question is simple, is this possible in flash using AS3? I could use simple instances of Movie clip layered onto the image but if the player is playing for more than a few minutes on the same level it could cause the screen to have hundred of movie clips on it at a time and this could cause massive performance issues.

if it is possible I would greatly appreciate someone letting me know, also some form of guidance would be much appreciated too such as a link to a tutorial or even just the function name so I can look it up myself in the help menu.

thank you in advance for any help you can offer.