Advanced Content Aware Scaling

In this tutorial i will teach you whats good about the new content aware scaling. Along with its slight downfalls that i will also show you how to overcome using some clever but simple techniques. You will require a copy of Photoshop CS4 to go through this tutorial as this is a new feature of photoshop and will not work in previous versions.
I am asuming that you have a beginner to intermediate level of experience in using photoshop prior to following this tutorial.
Step 1
Open image in photoshop you can use any image that has a person in the fore-ground and either trees or buildings in the background. To use the image in this tutorial just right click on the image and then save to hard drive.

Step 2
Double click on the background layer in the layers panel this is so you can unlock the image and go on to scale it. Photoshop CS4 will bring up a mini window for you to name the layer, we can leave this as layer 0 as we wont be using many layers in this tutorial.
Before

After

Step 3
Now go to the edit menu and click on Content Aware Scale alternatively using your keyboard you can press Alt+Shift+Ctrl+C on the PC. You will now be able to see adjustable anchor points around the image as you would get using the Free Transform tool.
Before

After

Caution point
If you now start to play about with the anchor points you will quickly realize that you will start to degrade the image and the poor girl is getting pretty distorted. We want to avoid this. Adobe Photoshop CS4 does have a setting that can help with preserving actual skin color pixels when using Content Aware Scale, the setting is a toggle button that shows up in the top right hand corner of the options bar for the CAS tool that we are using.

Here are two examples of the results.
This image is with out using the Protect skin tones setting

This image has Protect skin tones toggled on

As you can see in the first image the girl is not preserved at all but in the second the girl holds out very well but we loose on the car in the back ground. The only things we want to loose in this case are the road and trees. Lets learn how to achieve this
Step 4
We now need to create a alpha mask over the objects we want to protect in the image in our case the girl and the car. To do this select the quick selection tool and roughly highlight the girl and then to highlight the car as well hold the Shift key to include the car into the same selection.

Step 5
Go to the Select sub menu in the menu bar and click on save selection.

Step 6
This will bring up a mini window for you to name the alpha selections you have made remember that in this case we are saving both the girl and the car as one selection. In more complicated images that have more people or objects in them you will need to keep things on separate selections.
Save this selections as girl and car.

Step 7
Now if you go into the channels panel you will see a new Alpha channel under the default RGB channels. Now click on this channel and view that it shows us our selections in black and white, you can also make any further adjustments here if required.

Step 8
Go back to the RGB channel and hit CTRL + D to get rid our the highlighted selection on the image. This wont get rid of our alpha channel as it has been saved.

Step 9
Now go back into the CAS tool by clicking on Menu > Edit > Content Aware Scale and make sure that the Protect skin tones is toggled off as we wont be needing it because we have made our own selections. Now go slightly to the left to the Protect drop down and select girl and car this will protect what ever selections we have saved when we are using the CAS tool.

Step 10
Finally resize the image similar to the one below and see how both the car and the girl hold out very well. Photoshop CS4 has decided itself what parts of the road and trees to keep and to get rid of in order for the image to blend.

Step 11
Photoshop CS4 will now prompt you to keep the changes you have made or you can click tick on the far right of the CAS tool options bar when you are happy with your adjustments.

Heres the final result