Cannot change Colour within a picture

Question

I have tried to change the colour of the sky in a picture, the origianl sky is a washed out white due to poor weather conditions.
I have used the colour picker in the adjustmentstab and when i try to sample the origianl sky is comes up with a Hue of 0 and the main colour is RED ???
and also i cannot change this colour, what am i doing wrong?
Thanks
John

Answer 1

Hi John.
I will happily be corrected, but the information you're getting from Ir. Bob is misleading.
Aperture is an image development program.  One of it's core design principles is that it doesn't add data to an image -- it takes the existing data and adjusts it.  This is why there is no "editing" in Aperture.  In Aperture, one makes "adjustments".
Those adjustments (almost) all follow this pattern:
     original pixel values * adjustment parameter = adjusted pixel value
The original pixel value for your sky is, apparently, red.  This happened when you took the photograph.  You have, in photography parlance, "blown the highlights"  This isn't the forum to explain that, but you will most certainly want to research what that means and how to avoid it in the future.
Blown highlights can sometimes be recovered from the RAW data using the "Recovery" slider in the Exposure Brick.
From what you say, I don't think this will work for your image.
Since your highlights are blown, you will want to add blue to the image.  That kind of operation is not done with Aperture.  You will need to use a Graphics Editing package (such as Photoshop or any of the free or inexpensive programs like it).  Graphics Editors combine graphics elements.  They allow you to add data to images.
My reply covers a lot of basic concepts.  I strongly suggest some books or a course on photography as you move forward with Aperture.
Good Luck.