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; constructing a pixel value histogram based on pixel values of the 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.