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> **Possible Duplicate:**  
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> [Why can I adjust the white balance of a RAW file but not a JPEG file?](https://photo.stackexchange.com/questions/5410/why-can-i-adjust-the-white-balance-of-a-raw-file-but-not-a-jpeg-file) 
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I thought white balance adjustments were simple color-cast adjustments applied uniformly across the image? If this is the case, then why can I not accurately adjust the white balance in (for example) Aperture if the camera (SLR or iPhone in my case) has already made white balance adjustments?

Just to clarify, this I am referring to applying the white balance adjustment to the image as a JPEG. You cannot apply white balance adjustments to RAW files in the camera (at least not in any camera I know of).