1. An apparatus for reducing noise in an image, the apparatus comprising at least one processor to implement: a temporal noise reduction unit configured to remove temporal noise from an input frame by adjusting a temporal noise reduction intensity of the input frame based on a pixel-based motion degree and a block-based motion degree that are detected from the input frame and a reference frame, thereby to generate a first output frame; and a spatial noise reduction unit configured to remove spatial noise from the first output frame by adjusting a spatial noise reduction intensity of the first output frame based on similarity between peripheral pixels of the first output frame and the pixel-based motion degree and the block-based motion degree, thereby to generate a final output frame, wherein the spatial noise reduction unit comprises: a pattern matching unit configured to measure similarity between a patch with respect to a current pixel and patches with respect to peripheral pixels within a predetermined window of the first output frame; and a spatial noise filter configured to generate a second output frame by applying weights to the peripheral pixels according to the similarity between the patches and weighted-averaging, and generate the final output frame by weight-summing the first output frame and the second output frame by using a second motion weight according to the pixel-based motion degree and the block-based motion degree.