An image processing apparatus arranged to reduce noise in an input image, the processing apparatus comprising: generation means arranged to reduce the input image to generate a first reduced image and a second reduced image, the first reduced image having a higher resolution than the second reduced image; first detecting means arranged to detect a first edge of the first image, the first detecting means being configured to calculate, for each pixel of the first image, an edge probability, the edge probability being an index value that assumes a large value when there is a high probability that the pixel corresponds to the first edge of the first image; second detecting means (110, 501) arranged to detect a second edge of the second reduced image, wherein the second detecting means (110, 501) is arranged to calculate, for each pixel of the second reduced image, a low-contrast score that has a large value when the pixel of the second image is low in contrast and has a low value when the pixel of the second image corresponds to a smooth area or the pixel of the second image is high in contrast; processing means arranged to perform processing for reducing noise regarding the input image and the first reduced image; and compositing means arranged to composite the noise-reduced input image and the noise-reduced first reduced image, wherein the compositing means comprises deciding means arranged to decide a composite ratio for each pixel, based on the edge probability calculated by the first detecting means, and the low-contrast score calculated by the second detecting means (110, 501); wherein the compositing means is arranged to obtain pixel values in the first image and pixel values in the second image using the composite ratio. generation means arranged to reduce the input image to generate a first reduced image and a second reduced image, the first reduced image having a higher resolution than the second reduced image; first detecting means arranged to detect a first edge of the first image, the first detecting means being configured to calculate, for each pixel of the first image, an edge probability, the edge probability being an index value that assumes a large value when there is a high probability that the pixel corresponds to the first edge of the first image; second detecting means (110, 501) arranged to detect a second edge of the second reduced image, wherein the second detecting means (110, 501) is arranged to calculate, for each pixel of the second reduced image, a low-contrast score that has a large value when the pixel of the second image is low in contrast and has a low value when the pixel of the second image corresponds to a smooth area or the pixel of the second image is high in contrast; processing means arranged to perform processing for reducing noise regarding the input image and the first reduced image; and compositing means arranged to composite the noise-reduced input image and the noise-reduced first reduced image, wherein the compositing means comprises deciding means arranged to decide a composite ratio for each pixel, based on the edge probability calculated by the first detecting means, and the low-contrast score calculated by the second detecting means (110, 501); wherein the compositing means is arranged to obtain pixel values in the first image and pixel values in the second image using the composite ratio.