1. An image processing apparatus capable of applying an image processing set by a user to an image obtained by an image sensing unit, the apparatus comprising: a display unit adapted to continuously display images obtained from the image sensing unit in real time; an image processing unit adapted to apply the image processing to an image obtained by the image sensing unit in real time on the basis of a value set by a user operation; and a control unit adapted to control said display unit to alternately display a processed image, obtained from the image sensing unit in real time, to which the image processing is applied in real time by said image processing unit and a non-processed image, obtained from the image sensing unit in real time, to which the image processing is not applied by said image processing unit, so as to enable the user to compare the processed image with the non-processed image.