Tuning of local dimming function

A calibration device, comprising:

• a luminance measurement device configured to:
• measure a first luminance level of a measurement area of a display panel while the display panel is illuminated with four light sources of a backlight device, wherein the four light sources are arranged in two rows and two columns;
• measure a second luminance level of the measurement area while the display panel is illuminated with two of the four light sources, the two of the four light sources being arranged in a same row or a same column;
• measure a third luminance level of the measurement area while the display panel is illuminated with one of the four light sources;
• and
• a processor configured to determine, based on the first, second, and third luminance levels of the measurement area, a set of parameters corresponding to filter coefficients of a directivity filter used for a local dimming function implemented in a display device that includes the display panel, wherein at least certain of the filter coefficients are interpolated from other of the filter coefficients and wherein a subset of the other of the filter coefficients correspond to four times the third luminance level divided by the first luminance level.

A non-transitory tangible computer-readable storage medium that stores computer executable instructions which when executed causes a processor to:

• acquire a first luminance level of a measurement area of a display panel, wherein the first luminance level of the measurement area is measured while the display panel is illuminated with four light sources of a backlight device, wherein the four light sources are arranged in two rows and two columns;
• acquire a second luminance level of the measurement area, wherein the second luminance level of the measurement area is measured while the display panel is illuminated with two of the four light sources, the two of the four light sources being arranged in a same row or a same column;
• acquire a third luminance level of the measurement area, wherein the third luminance level of the measurement area is measured while the display panel is illuminated with one of the four light sources;
• and
• determine, based on the first, second, and third luminance levels of the measurement area, filter coefficients of a directivity filter used for a local dimming function implemented in a display device that includes the display panel, wherein at least certain of the filter coefficients are interpolated from other of the filter coefficients and wherein a subset of the other of the filter coefficients correspond to four times the third luminance level divided by the first luminance level.