Selecting With Channels

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Selecting with Photoshop Channels makes removing a complex object from the background much easier than with other tools.

Everyone of us has, at one time or another, tried to remove wispy hair or trees or your dogs with fuzzy coat with astonishingly poor results.

The lasso tools just don't work with these complex images.

The Quick Mask is good but it is very difficult to include those wispy little stands.

The Extract Filter - it works but it can be a challenge.
The RGB Channels let you look at each individual channel, find the best one to work with, make adjustments with levels and some do painting to achieve excellent results.

Using Channels

There are 8 steps to follow with this technique.

  1. Inspect the individual channels and choose the best one to work with - that will be the one with the highest contrast.

  2. Create a copy of the chosen channel.channels original

  3. Work with the levels dialogue to make your image as close to black and white as possible.

  4. Use the Brush tool to make the image completely black and white.

  5. Load the channel.

  6. Go back to the original and Paste in the copy.

  7. Put your selection on a new background.

  8. Clean Up.

For this tutorial I am removing the uniform blue sky from this image and replacing it with a more dramatic sky. There's nothing really wrong with the original sky but lets perk it up a bit.

Working With The Channels

With Photoshop open click Windows > Channels. You will see four channels named RGB, Red, Blue and Green. When you inspect each of the Red, Green and Blue channels you will see the original picture turn to Black and White.

Inspect each one of them in turn to determine which one has the most contrast between the Sky and the foreground.  

Here are the red, green and blue for this image.

channels red Red Channel
channels green Green Channel
channels blue Blue Channel

Close inspection of the contrast between the sky and the foreground in each of the three channels leads to the conclusion that blue has the most contrast.  

The next step is to ...

Make A Copy Of The Channel With The Most Contrast

This is a simple matter of dragging blue channel onto the new Channel Icon at the bottom of the  Palette - and here it is.

channels blue copy

Its been renamed Blue Copy.

Adjusting The Channel

The objective here is to make the sky totally white and the foreground (tugboat, water and trees) totally black.  

Activate the blue copy and then choose Image > Adjustments > Levels.

Near the bottom of the Levels Palette there are three Eyedroppers. The left one is the Black Eyedropper and the right one is the White Eyedropper. With the Black Eyedropper click on the darkest part of the image you want to keep.

channels levels black point channels levels white point
Eyedropper for black Eyedropper for white

The foreground may become totally black but more normally it will have some jet black areas and some areas that are grey. Keep clicking on the grey areas until you get the foreground as dark as possible.

Now get the White Eyedropper and click on the sky. This turns the sky white (or somewhat channelswhiter). Keep clicking on the sky until it is as white as possible.

When the channel is as close to black and white as you can get it, click OK.

You can see from the image that there are still some things that need fixing.  The white name on the back of the tugboat remained white and some of the highlights are still visible.

The areas that need fixing will be done with the paintbrush.

Paint Out Imperfections

Set your default colors to Black and White by pressing the D key and set Black as the foreground color and set the tablet Brush Dynamics to size.

Now get in there among the white areas that should be black and cover them up.  When you are satisfied with the foreground press the X key to make white the foreground color and clean up any areas in the sky that need cleaning.

Sometimes it can be difficult to find the edges as you so work here is a tip - select RGB at the top of the stack and all of the color will be returned - you will also have a red mask over your image.  Continue working on the copied layer (Blue Copy in this case).

This makes it easier to work with edges like wispy hair or whatever is giving you a problem.

Depending on the complexity of your image this process could take some time to complete. You can, however, save your work as a .PSD file and go back to it later.

When you have the edges nice and crisp turn off RGB Channel and just work on the copied channel again.  

When you are done the image should be completely black (foreground) and white (sky) - like this...

channels black and white

This two little specks in the top left are not errors or dust on your monitor - they are seagulls so I left them in the image.

Make A Selection

Now we want to do something with that nice black and white image. What we are going to do is load it as a selection.

The selection will be the white area and if you really want to keep the black area don't be concerned - it is easy to invert..

Here's what to do ...
  1. hold CTRL (Windows) or CMD (MAC) and click on the name of the channel (Blue Copy in this case) you are working with.  This loads your selection and you will see the little marching ants around the edges of the image and around the area you have been working.

  2. Now click on the top channel (RGB) to return to the full color image and turn off the little eyeball on the Blue Copy Channel or you will have the red mask visible.

  3. Go back to the Layers Palette.

  4. Just to insure that the image is not too fuzzy click on Select > Feather and set your radius to about 0.5. You can experiment with this setting. Click OK.

Paste The Selection

channels selection loaded
When you get to the layers palette you will see the marching ants around the sky area (in my case).

This is not the area I want  so it needs to be inverted - Select > Inverse - that should do it quite nicely.

Make the Background layer invisible by clicking the little eyeball and you will be pleased and amazed - a perfect selection of a complex area!

Your image will look something like this ...

Place The Image On A New Background

With this image the goal was to replace a rather dull sky with one that has more character and oomph.

To do this I needed a good sky image that would, more or less, match the original picture.  you can use one of your own images or find a suitable background on one of the free stock photo sites.

When you have your image you need to make sure it is the same size as the original image - common sense, right?

OK - you have your great image on its own layer and you have your new background - now you need to move the image onto its new background.

  1. Active the image layer  and press Ctrl-A or Cmd-A

  2. Grab the Move Tool, press the Shift Key (this will force your image to be centered on the new background), and then

  3. Drag your new image to the new background.

Thats it - all done - almost ...

Clean Up

In my image there was some ghosting between the trees and the new sky - quite unsightly itchannels-glow was.

You can eliminate the ghosting  with Levels or with the Burn Tool.

The Burn Tool is probably the easiest to use.  Set the Burn Tool to Highlights and lower the exposure to about 45%.  

Zoom in on the offending glow and set your pen to change size with pressure.

Slowly and carefully work on the glowing area until it is gone and you have a nice transition.

Check your work by pressing the TAB key once and the F key twice (this will eliminate all of the  menus and put your image on a black background.  To return to the edit screen press TAB once and F once.

When you are satisfied with the result flatten your layers and now you are done!

Where Can You Use This Technique?

Using Channels is a great way to make a selection of a complex image. You can even save the image and when you come back the selection channel will still be available.

Try it out on images like ...

  • Images on a  bad background.
  • Changing backgrounds
  • Skylines
  • Hair
  • Animal Fur
  • Trees
You can really do anything  - from something simple like Bubba here ...

channels bubba channels rollercoaster
Bubba on a bad background Bubba moved to a new background


Using Channels

Where to use

Complex areas such as:
  • Skylines
  • Trees
  • Hair
  • Portraits

Quick Tip

Before and After Previews
When Working With a Filter

When you are in a filter dialogue and want a quick before and after view just click on the little Preview window.

When you click and hold the BEFORE picture is visible and when you let go the AFTER picture is visible.

You can zoom in and out using the + and - buttons as well.

 Photoshop In A Day
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