University Relations
University of Minnesota : Driven to Discover.

Gallery Home

The Making of Picture Book Illustrations: What is Preseparated Art?

Full Color Camera Separated Art

Where Are You Going, Little Mouse front cover (Click to Enlarge)

Not all children’s books were illustrated using preseparated art. Many were illustrated in full color using a more traditional medium, such as watercolor or colored pencils. When this was the case the work of separating color was left to the camera person, who used a photographic process to divide the original piece of continuous tone copy into four halftone plates, one for each of the process colors.

This process involves photographing the artwork four different times, each time with a different color filter between the film and the artwork. Three of the filters correspond to the additive primaries--red, green, and blue. Each of these three color filters absorbs two of the additive primary colors of light and allows the third to pass through to the film.

A red color screen will absorb blue and green light and allow red light to pass through. The result is a photographic separation negative showing areas of varying shades of red light in the image. When this negative is transferred to a printing plate it is reversed, creating a positive image. This positive shows areas of the image that are not red. These not red areas are a combination of blue and green, or cyan.

This process is repeated with a green filter to create a magenta plate and a blue filter to create a yellow plate. A fourth filter, usually yellow or orange, is used to create the black plate. A halftone screen is also used when the separation negative is converted to a positive printing plate to capture varying tones.1

Where Are You Going, Little Mouse printed cover (Click to Enlarge)

Printed cover - click to view

The final printed book faithfully reproduces the original full color, continuous tone artwork. This camera-separation process made the reproduction of artwork in any medium possible. Unfortunately, it wasn’t always practical. The camera and filter method was not perfect, and manual color correction or retouching of the separation negatives was often required.2 This was a time consuming task performed by a camera person whose labor was expensive. It was also more costly to print in four colors than it was to print in only two or three.3


The high cost of printing camera separated full color artwork meant that most publishers of children’s books only employed it for a few books each season. It was typically reserved for established artists who were likely to generate enough interest to justify the additional cost. For most other books the artist was required to do the work of preseparating colors.

Ava Weiss and Paul Zelinsky explain why most children's books were preseparated

1. Jaffe, Erwin, et al. Color Separation Photography for Offset Lithography, with an Introduction to Masking. 1st ed. New York: Lithographic Technical Foundation, 1959. Print. 12-14

2. Foster, Joanna. Pages, Pictures, and Print: a Book in the Making. New York: Harcourt, Brace, 1958. Print. 65

3. Colby, Jean Poindexter. Writing, Illustrating and Editing Children's Books. New York: Hastings House, 1967. Print. 113-115, 186