Joint Photographic Experts Group, *.jpg. The de facto standard for image compression in digital imaging devices. JPEG is a lossy compression technique, capable of reducing digital images files to about 5% of their normal size. This is one of the reasons you can get as many images into your PowerShot digital camera as you can. The results in decompression of the files can cause "blockiness," the " jaggies," or "pixelization" in certain digital images. The greater the compression level the more pixelization or "blockiness" that will occur. The greater the pixel count, the less pixelization that may occur.