Changing Skies with Blend If

Quick reference

• 00:04 Hey everyone, in today's video I'm going to demonstrate a feature in Photoshop that
• 00:08 tends to be overlooked by the average user.
• 00:10 And that's the Blend If controls. This feature works quite well if you're
• 00:14 let's say, trying to replace the sky in one of your photos. For example, in this photo
• 00:18 here, we're going to attempt to replace the boring blue sky
• 00:21 with this mountainous background. Now, before we start messing with new
• 00:25 features,
• 00:26 let's analyze this photo for a second by looking at our channels.
• 00:29 When looking through our channels, we want to try and find the channels with the
• 00:32 darkest and the brightest areas, and you'll see why in a few moments.
• 00:36 Looking at the blue channel, we can certainly see it has the darkest areas
• 00:40 out of the three channels,
• 00:41 especially when it comes to the trees, which is probably our most important
• 00:45 focus area.
• 00:46 As for the bright areas, our red channel seems to have a nice amount of brightness
• 00:50 in the sign.
• 00:51 Keep that in mind for later on. I'm going to go ahead and simply drag the mountain
• 00:56 photo on top of the photo with the sign
• 00:58 and place it were I'd like it to show up in the background. Now that that's in place,
• 01:03 double click on the top layer to open up our layer styles dialogue box.
• 01:07 Usually when we're here, it’s to add things like outer glows or bevels,
• 01:10 but today we're going to stay within the ‘Blending Options’ section.
• 01:14 Down at the bottom, we have Blend If, which right now is set to grey.
• 01:18 This is where channel analysis comes into play; Let's change grey to blue.
• 01:22 The top bar will affect areas of our current layer
• 01:26 and the bottom bar will affect the layer underneath it, so because we want to keep
• 01:30 the top layer intact,
• 01:31 we're going to focus on the bottom bar. Now if you remember from a few moments
• 01:35 ago, on the blue channel
• 01:37 there were a lot of dark areas: watch what happens when I drag the dark
• 01:41 slider to the right.
• 01:41 Those areas which fall in this range are starting to appear in
• 01:46 front of our image.
• 01:48 I'm going to stop when I see the blue from the original sky leak into the image.
• 01:52 Now as you can probably tell, if I zoom into the leaves there are a lot of sharp
• 01:55 edges. So how do we deal with that?
• 01:57 Well, it turns out that this slider is actually made up of two sliders.
• 02:02 If you hold down your ALT or Option key and drag the left side
• 02:05 out, the slider will split into two. This will allow the colors to transition,
• 02:10 giving us a much cleaner result. Now in terms of the sky, it's looking pretty
• 02:14 nice, but looking at the
• 02:15 building, there are some clear problems. So we're going to
• 02:19 use the brightness in the red channel to fix it up.
• 02:22 Once changed to red, instead of dragging the dark slider,
• 02:26 grab the light slider and drag it over until the blue start seeping in again,
• 02:30 right around 160. Now, just like before we can split the slider to create a nice
• 02:35 transition.
• 02:36 I'm going to drive you to the right and pop this one around 220.
• 02:40 Good, that’s looking great. Let's go ahead and accept it and take a look at the result.
• 02:44 What's neat about this technique is that you can drag the layer around
• 02:47 and it still maintains the blend. But you might notice that the job isn't 100
• 02:52 percent complete.
• 02:53 While the trees are looking really nice, there are some leftover bits on the
• 02:56 building.
• 02:57 This can easily be taken care of with a layer mask.
• 03:01 Once a layer mask is applied,
• 03:01 paint over the remaining areas with a black brush and you're done.
• 03:05 If you use this feature properly, the Blend If controls can be very helpful,
• 03:09 but it won't work for everything.

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