Advice on cut out skies?

[theronster]

Hi all

I've tried to paste a sky into a photo that I quite like since the day I took it there was nothing but grey.

I'm unsure about the results to be honest


Does anyone have any suggestions as to how I would get a better overlay of the trees onto the lower layer of the sky? At the minute there is a very definite 'edge' to be seen around the top of the treeline.

[tontoshorse]

(i'd be interested too!),
nevertheless a good pic, good symmetry - I'd have a go at removing that outhouse on the right hand building. Good contast IMO too.

[wabbitt]

I'm assuming that your original sky is white or grey?

If it is then it should be pretty easy to do something in Photoshop.

Now I'm going to do all this from memory so sorry if I screw up along the way but I'mpretty sure this is the best way to do it.

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First things first is to change your photo to a regular layer (as opposed to a background). Hold down ALT and double click your Background layer. It should change to Layer 1 or something like that.

Click on the Channels tab and click through the red, green and blue channels. One of those will show the tree line in all it's glory. right click the channel and select duplicate. Click OK on the dialogue. It should create an alpha channel at the bottom of your channels.

Select that channel. Now go to Image>Adjustments>threshold. Drag the slider until the tree line and sky is nice and crisp. Don't worry about anything under the tree-line yet. Ignore it.

When you are happy, click OK. Now take your brush with Black as the foreground colour. Paint black over any white bits in the main picture.

when you are done click back on the RGB channel.

Now go to Select>Load Selection and pick your alpha channel.

When that's done you should see the marching ants around the tree line. Press the 'Mask' button at the bottom of your layer palette (looks like a little circle in a square). This should remove the grey part of the sky. (If I've screwed up and your main photo dissapears and the sky stays put, then press CTRL-I to swap the mask).

Now, create a new layer below your main photo and drop your new sky on it.

Voila... a new sky.

I'll check the method when I get home and check I'm not leading you own the garden path.

Dean

[wabbitt]

I should mention that the this is one of many ways to create a mask.

Another way to do it is to use curves on the alpha channel instead of threshold.

If you paste a linky to your original I'll have a bash and find the best way for you.

[theronster]

Well this is the original at Flickr, but at the reduced size for the web.

[wabbitt]

OK... I did a little 5 minute go at this. If I spent a little more time I'm sure I'd have it better, but this should get you on the way.

Forget the threshold because it didn't really work on this, but the curve technique did wonders.



I used the blue channel (as this had the most contrast) for the mask. I copied it and then ran a curves adjustment to pull the blacks down. I clicked the white eye dropper and clicked on the sky to lift it completely to white. Taking your time on this bit (which I didn't) will get it spot on.

Then I painted black all over the bottom part of the image.

Back to the RGB channel mode and then on with the rest.

Load the mask you've just created (I called mine 'Alpha')

Right... this bit I led you astray... hold down ALT when you click the mask button (this is the same as clicking the mask button and then pressing CTRL-I by the way).

Put your new sky on a new layer underneath your photo.

Hopefully you should now have a nice new sky.

If you see a bit of your old sky or white/grey fringing (like in mine), then simply click on the mask and either run your curves again, or what also works is very slightly running a gaussian blur on your mask.

Remember the mask is the key to this method.

Use the best tool in your arsenal to help you... your eyes.

Hope this helps matey!