How to crop the sky of a photo with the channels of photoshop (Easy)

In this first tutorial we will see how to cut a sky to replace it with another one in photoshop. For this we are going to use different tools that this fantastic photo editing program offers us.

The image that he has selected to cut out the sky is that of the Catalan Pyrenees, exactly in the Aran Valley in the Baqueira area at dawn. When the sky is completely clear, it will make our work a little easier.

Channel selection

To begin we go to the Channels tab that we have in the lower right, just next to the layers, as you can see in this image.

Once there we must select the channel that offers us a greater contrast between the sky and the rest of the landscape we want to keep in the photograph, in this case the mountains and all the lower part of them.

These are the three images that we will have when selecting only the Red, Green or Blue channels.

I would say that the biggest contrast is in the first one, which corresponds to the red channel, so we are going to work on this channel.

Now, with the red channel we select we go to the top menu bar and in the image we click to calculate.

Once inside, we must look for the configuration that most contrasts us with the photograph. In this case, in the mix tab I have selected the option of “live light”.

The picture that we have left after these adjustments can be seen below

Adjust levels

As you can see, the sky is getting completely white, but we still need a bit, so we are going to press with the channel selected in the left menu ctrl + l, this way we will open the level adjustment.

Once in levels is a matter of trying until finding the adjustments that leave in black all the part of the picture we want to keep and blank everything we want to erase, in this particular case the sky.

As you can see, what I have done has been to decrease the illuminations and increase the midtones a bit until the desired result is achieved.

It may be the case that you do not get the desired result and there are areas of the photo that are not completely white or black, in these cases we will use other tools, but we will see in another tutorial, in this we are seeing a very simple cut.

Select and cut

Once we have the levels adjusted we go to the top menu and click on load selection. We must select the selection that has the same name as the channel we have selected, in this case Alpha1.

Once you accept, you will see that you have selected all the part of the photograph that you want to keep. With this selected we go to layers and with the layer of our selected photo we click on layer mask on the bottom.

And then you can see how the program eliminates the part of the photograph that we wanted to replace or remove.

If we enlarge the photograph we can better appreciate the cut obtained.

And now you can save your picture in PNG or put a different sky.

To consider

Remember that when rerouting each photograph is a world. There are many ways to cut correctly and even with this system we can use other tools. In this case we have seen a very simple cut and a certain way of doing it, I think that to start familiarizing yourself with the different tools is more than enough.

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