Flat, smooth, single-colored surfaces will net you the most accurate color-matching results from ColorReader EZ. The device should be placed flush, against the surface you’re measuring (touching it – not just aimed towards it) to ensure no surrounding light can seep in which can affect the accuracy of the color reading. Textured surfaces like stucco or nubby woven fabrics and high-sheen surfaces can affect color accuracy, as can gradient color surfaces. If measuring a color on a pattern, make sure the portion of the color you are measuring is large enough (at least ¼” X ¼”) to ensure the lens covers the surface entirely.