Image processing device, image pickup device, computer, image processing method and program

Provided are an image processing device, image pickup device, computer, image processing method and program that make possible suitable image reduction processing in accordance with the presence or absence of an optical low-pass filter and/or colour filters in various patterns of arrangement and make possible generation of a reduced image in which image degradation such as Moire fringes is less noticeable. An image reduction processing unit (16) comprises a data acquisition section (70) that acquires information as to whether or not image pickup condition data is included in imaging data (including image pickup data) (30) and also acquires the content of imaging condition data. The image reduction processing unit (16) also comprises reduction processing discrimination means that uses the results of acquisition of the imaging condition data to distinguish at least one of: whether or not reduction-related processing (i.e. processing using a low pass filter or the like) has been performed related to reduction processing whereby reduced image data is generated from the image pickup data; a processing parameter (such as the cut-off frequency of low pass filter processing) of reduction-related processing; and a processing parameter (such as the reduction ratio) of reduction processing. The imaging condition data includes information relating to the presence or absence of an optical low pass filter and/or information relating to the arrangement of a colour filter.