>>im gonna use
this picture.
>>open up your picture on photoshop.
>>make a new layer on top, set it to screen (100%)
>>take ur basic circle brush and set the size too like 200+ use a size that satisfies you.
>>add a color orb to the screen layer
>>duplicate the base/background layer and drag it to the top, set it to overlay.
>>and your done :)
>>
finished look
>>quick and easy and you can add more colors, works on black&white or color.