1. An image processing apparatus comprising: block-motion-vector detecting means for detecting, by block matching, respective block motion vectors of a block including a subject pixel and a plurality of blocks adjacent to the block including the subject pixel; difference calculating means for calculating difference between pixel values of a pixel on a first field and a pixel on a second field, these pixels being used to generate the subject pixel, based on each of the block motion vectors detected by the block-motion-vector detecting means; pixel-motion-vector selecting means for selecting, as a pixel motion vector of the subject pixel, one of the block motion vectors that minimizes the difference calculated by the difference calculating means; inter-field-interpolation pixel generating means for generating a pixel value of the subject pixel by inter-field interpolation using the pixel on the first field and the pixel on the second field, based on the pixel motion vector selected by the pixel-motion-vector selecting means; intra-field-interpolation pixel generating means for generating a pixel value of the subject pixel by intra-field interpolation using pixels vertically or horizontally adjacent to the subject pixel; amount-of-error calculating means for calculating an amount of error that occurs, based on the pixel value of the subject pixel generated by the inter-field-interpolation pixel generating means, pixel values of the pixels vertically or horizontally adjacent to the subject pixel, the pixel value of the subject pixel generated by the intra-field-interpolation pixel generating means, and pixel values of pixels on fields temporally preceding and succeeding a field where the subject pixel exists, the pixels being located at positions corresponding to the subject pixel; and pixel-value determining means for determining a pixel value of the subject pixel based on the amount of error calculated by the amount-of-error calculating means, using the pixel value generated by the intra-field-interpolation pixel generating means and the pixel value generated by the inter-field-interpolation pixel generating means.