Tone-on-tone detail & noise suppression: The cloth swatches in the pinwheel were chosen because they show a lot of tone-on-tone detail, across a broad range of colors. This is just the sort of detail that noise suppression processing tends to flatten out. If you look at the detail in these swatches as the ISO increases, you'll see just where different cameras start to lose subtle detail. -- The white and tan swatches and the dark swatches tend to be particularly revealing of this. The label of the vinegar bottle (second from the right) is another great place to look for lost detail from noise suppression, as the image of the person at the top of the label is actually a depiction of a mosaic. The dark colors in the background and in the figure's clothes contain detail that's very quickly lost when a camera's noise suppression system kicks in. Cameras with really high-quality, low-noise sensors that require little noise suppression will be able to hold onto the detail in these areas, many others will show only a uniform swath of smudged color.