If you want to reduce the size of your image a bit more, you could convert your image to Indexed mode. That means that all of the colors will be reduced to only 256 values. Converting images with smooth color transitions or gradients to indexed mode will often give poor results, because it will turn the smooth gradients into a series of bands. This method is also not recommended for photographs because it will make the image look coarse and grainy.

Figure 6.4.  An indexed image can look a bit grainy. The left image is Wilber in its original size, the right one is zoomed in by 300 percent.