Most of the compression will be taken up in the solid background. Which allows for more detail in the beads. (Also no distraction from viewing the bead.) Compression is important for web-based images to reduce file size, which allows for faster loading of images onto the browser. For those not familiar with compression - the way it works is that it assigns the same value to similar pixels adjacent to each other. A large area of pixels with the same value is where the greatest compression with be.

The white feather bead image with black background is only 20k. The Tom Boylan bead, which shows more detail at the same compression level, is 80k. Well below the 169k max to post on BCN.