Abstract To reduce power consumption and improve image quality including contrast ratio and color gamut, LED backlight units (BLUs) consisting of many small blocks in 2‐dimensional space are implemented. Either white‐gray‐level luminance or color is controlled by the local dimming LED BLU. However, such a BLU can induce various recognizable artifacts. A method is proposed for exact block luminance calculation along with a new algorithm to correct local dimming artifacts. A new concept of color classes has also been developed to achieve extremely wide color gamut and to minimize color related artifacts.