1. A method comprising: obtaining, by a computing device, a plurality of images of a scene, wherein the plurality of images were captured by an image sensor, and wherein the plurality of images includes a first image and a second image, wherein a particular gain has been applied to the first image; determining an effective color temperature and a brightness of a first pixel in the first image; based on the effective color temperature and the particular gain, selecting a mapping between pixel characteristics and noise deviation of the image sensor, wherein the pixel characteristics include pixel brightness, and wherein the noise deviation characterizes error introduced by the image sensor when capturing images with the effective color temperature and the particular gain; using the selected mapping to map at least the brightness of the first pixel to a particular noise deviation; comparing the brightness of the first pixel and the particular noise deviation to a brightness of a second pixel of the second image; and based on the comparison, determining whether to merge the first pixel and the second pixel.