1. A method comprising: capturing, by an image sensor, a plurality of images of a scene, wherein each image of the plurality of images is captured using a different total exposure time (TET); downsampling the images in the plurality of images, wherein downsampling the images in the plurality of images comprises forming a plurality of high-average downsampled images and a second plurality of low-average downsampled images; constructing a pixel value histogram based on pixel values of the downsampled images, wherein constructing the pixel value histogram based on pixel values of the downsampled images comprises constructing the pixel value histogram based on pixel values of the plurality of high-average downsampled images and the plurality of low-average downsampled images; comparing the pixel value histogram to one or more reference pixel value histograms; and determining a payload TET based on comparing the pixel value histogram to the one or more reference pixel value histograms.