Compare character design methods. Children's books often feature simple or blatant imagery so that children can more easily grasp the point. For example, villainous characters are often drawn with wildly exaggerated, menacing expressions to strengthen the dichotomy between the bad and good characters. This helps children grasp the underlying message of the book.
Look for any underlying biased messages drawn into the illustrations. For example, it was once popular to draw evil characters as dark or dressed in black. In contemporary children's literature, doing so is sometimes considered to convey a racist sentiment, even if it is accidental. The most diverse children's literature will feature complex illustrations that do not rely merely on black and white to differentiate the characters.
Look for stereotypes conveyed through the characters or situations. Children's literature that enforces stereotypes may feature illustrations that are racist or sexist in nature, even if subtle. Consider the implications of even the best-intentioned or humorous stereotypes because these can reinforce a biased mindset in children readers.
Analyze the setting and background of each image. Children's literature often features colorful, exaggerated settings to grab children's attention. The general colors and setting of each illustration often reflects the mood of the story. Also pay attention to the perspective of each illustration. Just as in film, perspective can be used to convey underlying information. For example, drawing one character much closer to the foreground gives that character an overpowering presence in the illustration and, consequently, in the story itself.