1. A method of processing images containing a blotch, the method comprising: using at least one processor to perform operations comprising: accessing one or more component images of a target image, the target image including a first component image and a second component image; accessing one or more component images of a reference image, the reference image including a first component image and a second component image; determining a motion vector characterizing motion between the target image and the reference image; comparing, based on motion indicated by the motion vector, the first component image of the target image with the first component image of the reference image to produce a first-component comparison result; comparing, based on motion indicated by the motion vector, the second component image of the target image with the second component image of the reference image to produce a second-component comparison result; and determining that the first component image of the target image includes a blotch based on the first-component comparison result and the second-component comparison result, wherein comparing the first component image of the target image with the first component image of the reference image comprises determining a first-component difference between intensities of (i) a given pixel having a given location in the first component image of the target image and (ii) a corresponding pixel in the first component image of the reference image, the corresponding pixel in the first component image of the reference image being determined based on motion indicated by the motion vector, wherein comparing the second component image of the target image with the second component image of the reference image comprises determining a second-component difference between intensities of (i) a pixel having the given location in the second component image of the target image and (ii) a corresponding pixel in the second component image of the reference image, the corresponding pixel in the second component image of the reference image being determined based on motion indicated by the motion vector, and wherein determining that the first component image of the target image includes the blotch comprises identifying the given pixel as being part of the blotch based on the first-component difference and the second-component difference.