Placing Black Outlines in Photoshop
I am still working through the projects in the book Creative Photoshop CS4: Digital Illustration and Art Techniques by Derek Lea  and came across a series of particularly helpful steps in one project. These steps allow you to take any black and white drawing and place it onto an art board without having to re-draw the image or cut it out. I used to cut out the image and save it as a .png with a transparent background in order to place it in the new digital art work I was working on.
These steps are particularly helpful for any high contrast drawing, including cartoons and comic art, graphic designs and anything like a pen and ink drawing. If you have a line drawing on paper, get it ready in Photoshop by scanning it, adjusting the contrast and using the black and white eyedroppers in Levels to make the image high contrast black and white. I will show the steps here with an old piece of Dover clip art that I scanned:
1. Open your image. You want to invert it [as below] either use CTRL+I / COMMAND+I or go to Image > Adjustments > Invert.
2. Copy the inverted image [CTRL+A / COMMAND+A, CTRL+C / COMMAND+C or Select > All > then Edit > Copy]. Now go to the file you want to place the art in. Open the Channels palette, next to the Layers palette. Create an empty alpha channel by clicking the Create New Channel button at the bottom of the Channels palette [looks like the Create New Layer button]. Make sure this newly created alpha channel is selected and paste the art in it [CTRL+V / COMMAND+V or Edit > Paste]; see Example A below. This will also enable you to place the art you are moving into your project, even if there are colors or background elements already in the file; you can easily place a drawing over other elements; see Example B below.
3. Keep the new alpha channel selected and click the Load Channel as Selection button at the bottom of the Channels palette. Now go to the Layers palette and Create a New Layer at the top of the stack. Press “d” on your keyboard to set the foreground color to black then use ALT+Delete / Option+Delete to place the black line drawing. Use CTRL+D / COMMAND+D to Deselect the image [or use Select > Deselect].
Example B [shown with background colors]
4. You can now go about using the image, changing it and coloring it as you like now that the drawing is transferred into your project. I like to add layers between the background and the line drawing and color on those so as to not disrupt the line drawing. You can make each color its own layer for maximum control on complex projects.
FAST STEPS! :
- Open image (needs to be black & white high contrast) by Place onto a Layer of your existing document, rasterize layer
- Invert image -[CTRL+I / COMMAND+I (Image > Adjustments > Invert)]
- Select all, copy [CTRL+A / COMMAND+A, CTRL+C / COMMAND+C or Select > All > then Edit > Copy]
- Open Channels palette, create new channel (Alpha Channel) make sure it is selected
- Paste Art into Alpha Channel [CTRL+V / COMMAND+V]
- Load channel as selection (button, bottom of Channels palette)
- Make new layer in Layers Palette
- “D” to default color black, then ALT+Delete / Option+Delete to place the black line drawing
- Deselect the image [CTRL+D / COMMAND+D or use Select > Deselect], hide inverted Layer
- Paint on layers below lines