if you use photoshop, it would probably be easier to use the polygonal selection tool to select your subject (can be a person, flower, or anything u wanna extract from the picture). once you finish selecting the entire image, go to "select" then "modify" then "feather", then mess around with the "feather radius" to feather or blur your edges to make it appear less choppy. the number you use depends on how large the image is. you might want to use a low number, perhaps less than 10. when your done with that, then you can pasted it inot a new background. if it doesn't turn out the way you want, just go back to the image and use a different feather radius.
be sure you use your history palette to go back to right after you selected the object but before you applied the feather. that way you don't have to select all over again. that would suck. then use a different feather radius. keep doing this until you get it to look the way you want when you paste into another background.
ex:
see how my head is placed on a "motion blurred" background. I used the feather option to smooth out the image and make it less choppy looking.
i dont know how some people can crop out their images so flawless where they can place it on a different background and it looks nice and not all choppy. 
do you get what i'm saying...*sighs* if only i had an example...but...i can crop out my images but, i always have a hard time trying to crop out the fellas cause their hair is spikey....and it's hard to get every single spike...and then when i paste it to a new background (let's say white) you'll definately notice that the picture was cropped out all crappy and stuff...is there an easier way or a program that i can use to help? 
if so...can you lemme know please? 
thank you! 
