An apparatus and a method for extracting a background luminance map of an image, and a de-shading apparatus and method. The apparatus includes: a luminance extracting unit, configured to extract luminance values everywhere in the image to obtain a luminance map; a separating unit, configured to separate background from foreground of the image based on the luminance map, to obtain an initial background luminance map; a top and bottom luminance obtaining unit, configured to extract top and bottom luminance of the initial background luminance map, and in the case of a part of the top and/or bottom luminance being missing, to supplement the missing part utilizing existing data of the top and/or bottom luminance to obtain complete top and bottom luminance; and an interpolation unit, configured to perform interpolation on the whole image based on the complete top and bottom luminance, to obtain the background luminance map of the image.