I was asked off-line why I had some charts that were white with black lines so here is the explanation.

You do this test with both a positive and a negative chart (by whatever name you wish to call it). The chart above measures fill in or the creep of the black image through adverse edge effects or image scatter into the white bars. The other chart measures spread, or the creep of the black bars into the white background.

Due to the differences in exposure and chemical effects, each type of chart gives a subtly different result. I ran both types of test but just posted the chart with the white bars.

PE