How do I do this picture effect?

You know that effect where the whole pic is black and white except for one item on the pic? how do I do that?

You Need Photoshop
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in photoshop you can put a border around the item you want to keep in colour and then tell it to turn everything else B&W.

You could do a similar effect by creating a copy of the pic and turning it B&W and then cutting out the item and pasting it into the copied image. You could do this in almost any image editing software.

I downloaded
picasa2
from google. its free and it has that feature.