Insert yourself into a photo without using a blue screen.
By Alex Lindsay
A few months ago I showed you how to insert people from one photo into another photo. The original pictures I used were an African landscape pic and a photo of my kids in front of a bluescreen. Many of you dared, prodded, and pushed me to show you how to move the kids from one image to the other without having a bluescreen to make things easy. On today's "Call for Help" I'll show you how to do it.
The process in a nutshell
To get the job done, I duplicated the Red channel in the picture of the kids (the channel with the most contrast), quickly deleted the outer areas of the background, used Levels to increase the contrast, and fine-tuned the image with Dodge and Burn. Finally, I loaded the channel as a layer mask.
The whole process involves developing a mask or matte to specify the area of the image you want to work with, preferably using the image rather than by hand, which usually looks too clean. When you create a matte, you generate a black-and-white image that describes the transparency of a layer.
* White = Where the image is opaque.
* Black = Where the image is transparent.
* Gray = Semi-transparent pixels
When you create a selection, you draw an image like this but you only see the border where the marching ants show up.
Of the many ways to create a matte, today we're using the color channels. Each channel represents the amount of a certain color in a photo (red, green, blue, etc). If you can find a channel that looks even a little like the matte you want (white where the image should be opaque and black where it should be transparent), you can manipulate the image and pull a usable matte out of it. You'll also need contrast between the foreground and background. The more correction you do, the more damage to the edges will occur.
Here's how to start building the matte.
1. Look at the color channels to look for the greatest contrast between your foreground (in this case, my kids) and the background (the backyard).
2. Duplicate the layer with the most contrast. We'll use the Red channel.
3. Use the Polygon Lasso Tool to create a Garbage Matte and knock out all the information other than the background bordering your subject (the kiddos). By "knock out," I mean fill the area with black so you don't need to think about most of the background, just the edges (all that really matters).
4. Click Image, Adjust, Levels and increase the contrast by pushing the white and black points inward.
But using Levels won't be enough. Since some areas of the image are more delicate than others, you can't apply corrections to the entire image or it will look unbalanced. The effect will be too much in some areas and too little in other areas.
To handle the problem, use the Dodge and Burn tools to push whites up and blacks down gently. While it takes a few minutes to work the whole image, it's an effective way to adaptively adjust the matte.
There you go!