On Tue, 22 Jul 2008 13:49:10 +0100, Invisible wrote:

> OK, that's just absurd. The sofa and the rug are *exactly* the same
> colour. How the hell can the machine tell them apart? Additionally, how
> on earth can it tell what colour they were originally? That's
> impossible...

Except it clearly isn't impossible, because it was done.  The way this 
works is by using white balance.  I've done it myself many, many times 
with old photos in the GIMP.

But the sofa and the rug aren't exactly the same colour - the rug is 
darker than the sofa (? looks like a chair to me).  Adjusting the white 
balance of the photo involves picking out something that actually is/was 
white (like the white on the baby's shirt).  That gives the computer a 
reference to make the adjustments from.  When photos age, they tend to 
age consistently and the colours adjust with consistency.  The computer 
basically is doing an "undo" on the age effect applied by real life.

Jim

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