What is a reference image, you may ask? A reference image is a picture you use to inspire your drawing or illustration. You do NOT copy it exactly, unless, of course, it’s for personal use only. However, if you’re going to upload it online or make money off of it, then at least some aspects have to be changed.
For example, you draw a portrait of a person. You use a photo to guide you. But to make it your own and not be considered plagiarized, you should change, say the eye color, remove a piece of jewelry, etc.
Another trick I’ve come up with on my own is mixing and matching facial features to create illustrations of people. I would use different images from various sources, like Google or my school yearbooks. I would draw one person’s set of eyes, another’s nose, another’s smile, and so forth, on one character. As long as it doesn’t look obvious and you change some details, you’re fine.
Reference images are also useful for body positions, scenery, backgrounds, and more. In fact, if you go into illustration or animation, then reference images are musts. You need to make the art appear credible. Drawing just from your imagination will cause more people to consider you illegitimate.
Of course, no artist is perfect. In fact, many cartoons have inconsistencies with their art. For example, a character’s eye color may change. Or a tree may disappear. This is easily noticed by audiences.
So there you have it. Now have fun illustrating using reference images.