1. An image processing apparatus that removes noise from an input image, the image processing apparatus comprising: a memory; and a processor coupled to the memory, wherein the processor executes a process comprising: creating a basic-structure component image representing an image that has the input image except an edge smoothed while preserving the edge in the input image; creating a detail component image representing an image by subtracting the basic-structure component image created from the input image; performing a multiresolution transform processing in which the detail component image is decomposed to a low frequency component and a high frequency component and each of a horizontal direction low frequency component and a horizontal direction high frequency component in each of the low frequency component and the high frequency component are decomposed to a vertical direction low frequency component and a vertical direction high frequency component; performing noise removal on each vertical direction high frequency; and performing an inverse multiresolution transform processing in which the vertical direction high frequency component from which noises are removed and the vertical direction low frequency component are combined, the horizontal direction low frequency component and the horizontal direction high frequency component are combined and the low frequency component and the high frequency component are combined, to create a noise-removed detail-component image.