Image output apparatus and method for outputting image thereof

An image output apparatus comprising:

• an image input unit which receives a current image frame and a previous image frame;
• an adjustment unit which adjusts at least one of a maximum grayscale value and a minimum grayscale value of the current image frame according to grayscale values of the current image frame and the previous image frame;
• a generation unit which generates an input and output grayscale function having the maximum grayscale value and the minimum grayscale value which have been adjusted;
• and
• an output unit which adjusts a grayscale of the current image frame according to the input and output grayscale function generated by the generation unit and outputs the current image frame.

A method for outputting an image of an image output apparatus, the method comprising:

• adjusting at least one of a maximum or minimum grayscale value of a current image frame according to grayscale values of the current image frame and a previous image frame;
• adjusting a grayscale of the current image frame according to a grayscale function corresponding to the adjusted maximum or minimum grayscale value;
• and
• outputting the current image frame.