Method for correcting local-dimming parameters through global backlight adjustment and circuit system thereof
A method for correcting local-dimming parameters through global backlight adjustment and a circuit system are provided. The circuit system connects with a backlight control circuit of a display. In the method operated in the circuit system, when an image is received, the pixel values of each of the regions divided from the image can be counted so as to obtain a local maximum and a local average of every region, and a global average of the image. The region having a dark-field halo can be detected based on a local difference between the local maximum and the local average. A leakage level can be obtained by determining an impact of the dark-field halo on the whole image based on a threshold. The leakage level and the global average are referred to for calculating a gain for global backlight adjustment after performing local dimming.
1 . A method for correcting local-dimming parameters through global backlight adjustment, performed in a circuit system, comprising:
receiving an image and obtaining pixel values of each of multiple regions divided from the image;
detecting one or more regions having dark-field halo from the multiple regions according to the pixel values of each of the multiple regions; and
determining whether or not to perform the global backlight adjustment on the image when a local dimming process is performed on the image according to a quantity ratio of a quantity of regions having dark-field halo to a quantity of global regions.
2 . The method according to claim 1 , wherein the image is divided into the multiple regions, a local backlight brightness corresponding to each of the regions is provided according to the pixel values of each of the regions, and the circuit system outputs local-dimming parameters to a backlight control circuit after the local dimming process is performed.
3 . The method according to claim 2 , wherein a local maximum and a local average of each of the multiple regions are obtained according to the pixel values of each of the regions, and a local difference between the local maximum and the local average of each of the regions is referred to for determining whether any dark-field halo occurred in each of the regions.
4 . The method according to claim 3 , wherein, when the quantity ratio of the quantity of the regions having dark-field halo to the quantity of global regions is larger than a ratio threshold, the global backlight adjustment is performed on the image, and the circuit system outputs local-dimming parameters through the global backlight adjustment to the backlight control circuit.
5 . The method according to claim 4 , wherein the pixel values of each of the multiple regions divided from the image are calculated, and a global average of the image is obtained; when the quantity ratio of the quantity of the regions having dark-field halo to the quantity of global regions is larger than the ratio threshold, the global average is referred to for determining whether the global backlight adjustment is to be performed on the image.
6 . The method according to claim 5 , wherein an adjustment ratio for reducing backlight brightness when global backlight adjustment is performed on the image is obtained by querying a lookup table according to the global average; wherein the lookup table records multiple adjustment ratios of multiple global averages to corresponding reduced backlight brightness.
7 . The method according to claim 6 , wherein a quantity of regions of which the local average of each of the multiple regions is smaller than a first threshold and the local difference is larger than a second threshold is counted; and a ratio of the quantity of the regions to the quantity of global regions indicates a halo level after the local dimming process is performed on the image, and both the halo level and the adjustment ratio corresponding to the global average are referred to for calculating a gain used for performing global backlight adjustment.
8 . The method according to claim 7 , wherein, when the halo level is smaller than or equal to a level threshold, the global backlight adjustment is not performed; and, when the halo level is larger than the level threshold, the global backlight adjustment is proportionally performed according to the halo level.
9 . A circuit system electrically connected with a backlight control circuit, and the circuit system performing a method for correcting local-dimming parameters through global backlight adjustment, comprising:
receiving an image and obtaining pixel values of each of multiple regions divided from the image;
detecting one or more regions having dark-field halo from the multiple regions according to the pixel values of each of the multiple regions; and
determining whether or not to perform global backlight adjustment on the image when a local dimming process is performed on the image according to a quantity ratio of a quantity of regions having dark-field halo to a quantity of global regions.
10 . The circuit system according to claim 9 , wherein the circuit system operates the method for correcting local-dimming parameters through global backlight adjustment by firmware or a system on a chip; in the method, the image is divided into the multiple regions, a local backlight brightness corresponding to each of the regions is provided according to the pixel values of each of the regions, and the circuit system outputs local-dimming parameters to a backlight control circuit after the local dimming process is performed.
11 . The circuit system according to claim 10 , wherein a local maximum and a local average of each of the multiple regions are obtained according to the pixel values of each of the regions, and a local difference between the local maximum and the local average of each of the regions is referred to for determining whether any dark-field halo occurred in each of the regions.
12 . The circuit system according to claim 11 , wherein, when the quantity ratio of the quantity of the regions having dark-field halo to the quantity of global regions is larger than a ratio threshold, the global backlight adjustment is performed on the image, and the circuit system outputs local-dimming parameters through the global backlight adjustment to the backlight control circuit.
13 . The circuit system according to claim 12 , wherein the pixel values of each of the multiple regions divided from the image are calculated, and a global average of the image is obtained; when the quantity ratio of the quantity of the regions having dark-field halo to the quantity of global regions is larger than the ratio threshold, the global average is referred to for determining whether the global backlight adjustment is to be performed on the image.
14 . The circuit system according to claim 13 , wherein an adjustment ratio for reducing backlight brightness when global backlight adjustment is performed on the image is obtained by querying a lookup table according to the global average; wherein the lookup table records multiple adjustment ratios of multiple global averages to corresponding reduced backlight brightness.
15 . The circuit system according to claim 14 , wherein a quantity of regions of which the local average of each of the multiple regions is smaller than a first threshold and the local difference is larger than a second threshold is counted; and a ratio of the quantity of the regions to the quantity of global regions indicates a halo level after the local dimming process is performed on the image, and both the halo level and the adjustment ratio corresponding to the global average are referred to for calculating a gain used for performing global backlight adjustment.