Evaluating Style Working effectively with compression involves understanding that different types of images are better suited to different types of compression. Line art is the style that contains a lot of solid colors and lines, such as what you would find in a graphic, illustration or logo. Continuous tone art is the style that contains subtle gradations or tones, like those found in photographic content.
Hybrid art is a combination of both styles.
Different compression types are designed for different style images. GIF compression works much better on line art than photographs. JPEG compression works much better on photographs. Hybrid imagery will work better with JPEG or GIF, depending on the image. Identifying the style of the image in question will help you make the decision of where to start on your quest for image compression.