Replacing sky in RE shots?

[littlemike]

<p>I'm doing some photography for local real estate agents, often using HDR or exposure blending. For the exterior shots, I can't always count on the kind of pretty blue skies that I'd like and I'm struggling with replacing the sky, as shot, with some other sky shots (blue skies, puffy clouds -- you know, postcard skies) that I've taken. </p>

<p>Trees and foliage are giving me trouble. I can't seem to find a way to select sky (or non-sky) stuff cleanly enough to avoid outlines or odd artifacts around branches and leaves when I try to composit the fake sky into where the original sky was. </p>

<p>Anyone here an old hand at this can offer a tip or two? I'm familiar with working with layers.</p>

<p>RAW, Lightroom, Photomatix, CS3. </p>

[swenson]

<p>First you have to be tedious with your selection. Using a mask on green channel for trees for example. You can either feather the edges option or do it mannually with very small smudge tool at high mag 400% or more.<br /><br />Aslo, make sure that the sky that you paste in matches the original. I've made a library of early morning, morning, early afternoon afternoon with sun to back, slightly left, lefy, slightly right and right. I then pick on that most closely matches the original scene. Otherwise the result may look like it's from a strange planet with two suns. <br /><br /></p>

[swenson]

<p>One more thing I forgot. I've found that I've had better luck stiching a bunch, usually two rows, of frames together so that the blank sky backgrounds are much larger than original. That gives you room to move things aroung as I usally, cut non-sky portions of original image and paste to blank sky instead of pasting new sky to original.</p>