About PNG-24 format

The PNG-24 format supports 24-bit color. Like the JPEG format, PNG-24 preserves the broad range and subtle variations in brightness and hue found in photographs. Like the GIF and PNG-8 formats, PNG-24 preserves sharp detail, such as that in line art, logos, or illustrations with type.

The PNG-24 format uses the same lossless compression method as the PNG-8 format. For that reason, PNG-24 files are usually larger than JPEG files of the same image. PNG-24 browser support is similar to that for PNG-8.

In addition to supporting background transparency and background matting, the PNG-24 format supports multilevel transparency. Multilevel transparency allows you to preserve up to 256 levels of transparency to blend the edges of an image smoothly with any background color. However, multilevel transparency is not supported by all browsers.

Optimizing Images for the Web > Choosing a file format for optimization > About PNG-24 format