To quote the inestimable choadwarrior:
To convert to jpg, save the comic, then do a print screen and paste the image into another program like photoshop, paint, etc to play with the image.
To convert to a png, click the Make a Donate button on the bottom of this screen and as soon as Brad has your money, another magic button will appear on your saved comics which will let you convert and save to png in one step. Then you can adjust the png just as you did the jpeg.
You can take the heart out of the hooker but you can't take the hooker out of the heart. -- Frankenhooker