In classic approaches to children's illustration a variety of mediums are used. The most common classic mediums for illustrating picture books and book covers consist of ink with watercolor, pencil with watercolor wash, acrylics and colored pencil. Many children's chapter books and middle-grade readers also include spot art. In this case, line drawings in pen and ink serve as the most common approach. The classic approaches continue to be the choice for many illustrators.
Many artists choose to create computer-generated children's book illustrations, especially graphic novelists. Professional art illustration software is expensive, but on-line illustration programs, such as GIMP and Inkscape, are available for no cost and can produce quality work. Computer-generated illustration simplifies the revision process, saving time. It also allows artists to reproduce a wide variety of illustration styles. These advantages make computer-generated art a popular choice for illustrating children's books.
Photo illustration is a popular choice for children's books about science and social studies. It is also a popular choice for young adult book covers. Stock photos are used widely in the children's educational book market. Photographs provide the wonder of realism to many children's books, but this art form is not limited in terms of whimsy. For example, some photographers devise elaborate dioramas of re-purposed everyday objects and photograph them to tell stories. Photo-illustrated picture books have enduring popularity with children.
Many artists use specialized art forms to illustrate children's books. Some artists construct their artwork from paper scraps to form collages. Others capture their audience through the use of colorful print-making techniques. Still others use batik, clay or quilts to tell their stories. These illustration styles work well for folk art and outsider art, a style set apart by its childlike openness. There is no limit to the number of original approaches, and novelty illustration represents a significant portion of the children's book illustration market.