An image processing apparatus for correcting color-shift in a displayed image due to brightness change of blue sub-pixels of a display panel with an added a blue-light filter configured to filter blue light, the image processing apparatus comprising: a cache memory configured to store a cache image comprising initial grayscale levels corresponding to respective brightness of a plurality of subpixels in a pixel at a current time; a grayscale level corrector configured to generate a set of N corrected grayscale levels of brightness of a blue sub-pixel for a correction scheme, the set of N corrected grayscale levels respectively one-to-one corresponding to a set of N original grayscale levels from a minimum 0 sequentially up to a maximum N-1 of the blue sub-pixel of the display panel without the added blue-light filter; and an image processor coupled respectively to the cache memory and the grayscale level corrector, and configured to adjust an initial grayscale level of at least one sub-pixel in the pixel to a reset grayscale level, and to output a grayscale voltage based on the reset grayscale level for driving the at least one sub-pixel of the pixel in the display panel for displaying a corrected image, wherein the image processor is configured to process at least a portion of the cache image to calculate an average grayscale value of the initial grayscale levels of the blue sub-pixels in the at least a portion, to adjust an initial grayscale level of each sub-pixel other than the blue sub-pixel in the pixel in the at least a portion based on a first correction scheme when the average grayscale value is greater than a threshold value, and to adjust an initial grayscale level of the blue sub-pixel in the pixel in the at least a portion based on a second correction scheme different from the first correction scheme when the average grayscale value is smaller than or equal to the threshold value, and to output the corresponding grayscale voltage for each sub-pixel, based on the corresponding adjusted grayscale level, in the pixel in the display panel for displaying a corrected image. a cache memory configured to store a cache image comprising initial grayscale levels corresponding to respective brightness of a plurality of subpixels in a pixel at a current time; a grayscale level corrector configured to generate a set of N corrected grayscale levels of brightness of a blue sub-pixel for a correction scheme, the set of N corrected grayscale levels respectively one-to-one corresponding to a set of N original grayscale levels from a minimum 0 sequentially up to a maximum N-1 of the blue sub-pixel of the display panel without the added blue-light filter; and an image processor coupled respectively to the cache memory and the grayscale level corrector, and configured to adjust an initial grayscale level of at least one sub-pixel in the pixel to a reset grayscale level, and to output a grayscale voltage based on the reset grayscale level for driving the at least one sub-pixel of the pixel in the display panel for displaying a corrected image, wherein the image processor is configured to process at least a portion of the cache image to calculate an average grayscale value of the initial grayscale levels of the blue sub-pixels in the at least a portion, to adjust an initial grayscale level of each sub-pixel other than the blue sub-pixel in the pixel in the at least a portion based on a first correction scheme when the average grayscale value is greater than a threshold value, and to adjust an initial grayscale level of the blue sub-pixel in the pixel in the at least a portion based on a second correction scheme different from the first correction scheme when the average grayscale value is smaller than or equal to the threshold value, and to output the corresponding grayscale voltage for each sub-pixel, based on the corresponding adjusted grayscale level, in the pixel in the display panel for displaying a corrected image.