This is a very good quality image. Because this is a graphic and not a photographic image, this is probably better image quality that is necessary or suitable. By changing this image to a GIF formatted file (see next image example) the file is considerably smaller, but the appearance of image quality is not substantially reduced.

This image is of lesser quality, but because it is a graphic and not a photograph, it resembles the larger JPG image above, although it is only about 2/3 the file size. For photographic images this same approach to file optimization may be less successful.

This is the smallest of the three images, and you can probably see the appearance of image quality is slightly less than the previous two images. The graphic is still quite legible though, displayed at the same size as the previous two images, but considering that this file is less than half the size of the first image file, the increased download speed of the image may be considered worth the image quality compromise.