The photo of the Italian hill town (“town_too_blue.psd”) has several problems. First, I realize that it’s kind of boring. Yes, it looks like a nice town, but there’s nothing notable or unusual about it. That’s why we’re going to put a bird on it. Also, although it was photographed near sunset, the golden light seems to be missing. It’s too blue. We’ll fix that in Lesson D, shortly.
First, let’s deal with those ugly blemishes in the sky. These appear to be bits of dust on my camera’s sensor and so are likely in the photos I made shortly after this one too. To deal with these, we’re going to use a powerful (but simple-to-use) tool and a professional workflow. See the “Retouching & Repair” chapter in the Compendium for much more.
Retouching is almost always obscuring flaws or blemishes with more acceptable material. That is, we take good bits from one part of an image (or another one) and put those over the bad bits. Because I make mistakes or change my mind, I use layers when I do this. I put the good bits on their own layer. If I later realize I made an error, I simply erase that bit.
That is now the active (highlighted) layer in the Layers panel. Of the many tools Photoshop has for retouching, let’s just go with the one that’s used most often.
Even the spot on the roof of the church is fixed easily. If you make a mistake, undo is a quick ⌘-Z/Ctrl-Z.