The differential between foreground lettering a sign and the background panel.

When the color of the vinyl panel and trim are contrasting or different rather than matched: almond siding and linen trim as an example.

Color contrast refers to how close hues are in value. The human eye requires good contrast for visibility and legibility. Contrast creates visual interest and helps deliver accurate information. It can make a big difference on a web page. Colors that are close in value tend to blur together, and their borders "melt." This can create legibility problems. For example, black text on a dark blue background is difficult to read.

subjective judgment on the apparent luminous difference or intensity of two colors when placed close to one another.