A display data correction apparatus is provided with: a control circuit responsive to an input gray-level value for initially providing first to N-th control points (N≥3) defined in a coordinate system in which a first coordinate axis is associated with the input gray-level value and a second coordinate axis is associated with an output gray-level value to be calculated for the input gray-level value; and a processing circuit obtaining an output gray-level value by repeating an update operation in which the first to N-th control points are updated. The degree (N−1) Bezier curve is used as an approximated curve of the gamma curve. The output gray-level value is finally obtained as the coordinate value of a specific point in the degree (N−1) Bezier curve along the second coordinate axis, where the specific point has the coordinate value closest to the input gray-level value along the first coordinate axis.