An image processing apparatus (1, 2, 3, 4, 5) for sharpening an input image by generating a frequency component higher than a frequency component contained in an input image signal (S in) representing the input image, the image processing apparatus (1, 2, 3, 4, 5) comprising: a vertical filter configured to remove, at least from a high frequency portion in a horizontal direction contained in the input image signal (S in), a high frequency portion of a frequency component in a vertical direction of the input image signal (S in); a horizontal sharpening processing unit (FEh) configured to generate a harmonic in the horizontal direction containing a frequency component higher than the frequency component in the horizontal direction contained in the input image signal (S in); a horizontal filter configured to remove, at least from a high frequency portion in the vertical direction contained in the input image signal (S in), a high frequency portion of a frequency component in the horizontal direction of the input image signal (S in); and a vertical sharpening processing unit (FEv) configured to generate a harmonic in the vertical direction containing a frequency component higher than the frequency component in the vertical direction contained in the input image signal (S in), wherein a horizontal direction processing unit in which the vertical filter is disposed at a preceding stage of the horizontal sharpening processing unit (FEh) and a vertical direction processing unit in which the horizontal filter is disposed at a preceding stage of the vertical sharpening processing unit (FEv) are connected in parallel, and an amplifier is connected to a subsequent stage of any one of the horizontal direction processing unit and the vertical direction processing unit and also to a preceding stage of the other, wherein the amplifier functions as a switch for switchover between parallel execution and series execution of the vertical direction processing unit and the horizontal direction processing unit, based on an amplification factor β. a vertical filter configured to remove, at least from a high frequency portion in a horizontal direction contained in the input image signal (S in), a high frequency portion of a frequency component in a vertical direction of the input image signal (S in); a horizontal sharpening processing unit (FEh) configured to generate a harmonic in the horizontal direction containing a frequency component higher than the frequency component in the horizontal direction contained in the input image signal (S in); a horizontal filter configured to remove, at least from a high frequency portion in the vertical direction contained in the input image signal (S in), a high frequency portion of a frequency component in the horizontal direction of the input image signal (S in); and a vertical sharpening processing unit (FEv) configured to generate a harmonic in the vertical direction containing a frequency component higher than the frequency component in the vertical direction contained in the input image signal (S in), wherein a horizontal direction processing unit in which the vertical filter is disposed at a preceding stage of the horizontal sharpening processing unit (FEh) and a vertical direction processing unit in which the horizontal filter is disposed at a preceding stage of the vertical sharpening processing unit (FEv) are connected in parallel, and an amplifier is connected to a subsequent stage of any one of the horizontal direction processing unit and the vertical direction processing unit and also to a preceding stage of the other, wherein the amplifier functions as a switch for switchover between parallel execution and series execution of the vertical direction processing unit and the horizontal direction processing unit, based on an amplification factor β.