1. A denoising apparatus comprising: an image input unit configured to receive pixel data including color information of pixels included in a correction target image; a denoising unit configured to denoise the pixel data by a weighted-averaging method, wherein a weight is set to a maximum value when a difference value between a correction target block and a comparison target block in the correction target image is zero, decreases linearly to zero as the difference value increases until it reaches a threshold value, and is set to zero when the difference value is equal to or greater than the threshold value; and an image output unit configured to output denoised pixel data, wherein the denoising unit is configured to assign a corrected weight value to at least a guaranteed number of comparison target blocks for an impulse block, and the impulse block is a correction target block for which the number of non-zero weight valued comparison target blocks is less than a predetermined guaranteed number.