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In the previous module, we masked the tree using one channel.
In this module, we will be using multiple channels in order to mask a tree.
For this exercise, let us use data file tree.jpeg.
Once you have opened the necessary data file, double click on the Channels panel.
Tree jpeg is also an RGB picture, and it is composed of three colors channel: red, green, and blue.
Each channel shows the amount of that color in the image on a gray scale.
Again we want to choose channel that has the most contrast when comparing the tree to the rest of the image.
Since the sky is fairly distinct from the tree, and has a fair amount of blue tonal area,
we are going to use the blue channel.
Let us right click on the blue channel, then duplicate it.
Let us rename this channel Alpha, then when finished, click on the OK button.
The bark of the tree is a bit redder than the back drop, so we are going to use the red channel as well.
Let us right click on the red channel, then duplicate that channel.
Click on the OK button.
Let us turn the Red copy channel on and turn the Red channel off.
Now let us start balancing the channels.
Make sure that the Red copy channel is selected, then click on the Image menu.
Scroll down to adjustments, and select levels.
Our goal is to make the tree bark very distinct from the background.
In the previous module when we were adjusting a channel we used the shadow, highlight, and midtone slider.
In this situation, we are going to show you how to manually type in the input levels.
Let us click, and select the first input level, and type in fifty.
Highlight the input level beneath the midtone slider, and type in 0.85.
And lastly, select the input level underneath the highlight slider, and type in two hundred and twenty two.
When finished, click on the OK button.
Now let us load this channel as a selection, so that we can edit it further in the Alpha channel.
So with the Red Copy channel selected, and only its visibility turned on
click on the Load Channel as Selection button, located at the bottom of Channels panel.
Afterwards, select the Alpha channel.
Click on the Image menu
Scroll down to adjustments, then select Levels.
Now our goal here is to darken the white speckles in the bark area of the tree.
So let us first select the Input level underneath the shadow slider and type in 120.
Then select the input level under the midtone slider, and type in 1.2.
We are going to keep the input level underneath the highlight slider at 255.
When you are all finished, click on the OK button.
Now we are ready to adjust the Alpha channel.
But before we do, let us click on the Select menu, and click on Deselect.
Now we are ready to adjust the Alpha channel.
Let us go to the Image menu, scroll down to Adjustments, and select Levels once again.
In the Input level underneath the shadow slider, we want to type in 31.
And in the input level, underneath the highlight slider, we want to type in 145.
Or if you would like, you can manually adjust the shadow and highlight slider
so that the tree is completely black, and the background is completely white.
When finished, click on the OK button.
Again we have to invert the tree in the background so that the tree is white and the background is black.
Because remember, white means on and black means off, and we want the tree to be on.
So let us click on the image menu, scroll down to adjustments, and select Invert.
Now we are ready to load the tree.
So with the Alpha channel selected, click on the Load Channel as a Selection button underneath the Channels panel.
Double click on the Layers panel, then right click on the Background layer.
Let us duplicate that layer.
Click on the OK button.
And with the Background copy layer selected, click on the Add Layer Mask button located on the bottom of the Layers panel.
To see our mask, let us turn our Background layer off.
Now we still have to mask out the hill, so that only the tree is remaining.
So let us click on the layer mask, located on the Background Copy layer.
Then right click on the Lasso tool, and select Polygonal Lasso tool.
We are going to make a rough selection of the hill, by first clicking on the outside of the image
And creating anchor point along the border of the tree.
Make sure to close your selection by clicking on the first anchor point.
Then we have to go to the Edit menu, and select Fill.
And in the Fill dialog box, click on the Use drop down arrow, and select Black.
Click on the OK button when you are finished.
Now the only thing remaining is the tree.
Let us go to the Select menu, and Deselect.
Before we finished, let us refine our mask by double clicking on the Masks panel.
Click on the Mask Edge button, and preview your mask against different backgrounds.
Let us refine our mask against the black background, and contract our mask.
We can also change the radius and feather our mask as well.
When finished, click on the OK button.