1. An apparatus comprising one or more processors configured to: process a first image at a first resolution to generate a first solved image at the first resolution; determine a difference between the first solved image and a function of the first image; generate a second solved image at a second resolution higher than the first resolution based at least in part on the difference between the first solved image and the function of the first image; downsample a second image at the second resolution to generate the first image prior to processing the first image; and upsample a delta image representing the difference between the first solved image and the function of the first image to generate an upsampled delta image at the second resolution, and wherein the second solved image is generated by combining the upsampled delta image and the second image, wherein the second image comprises a pixel value denoted as I(x), where x is a pixel coordinate between and including coordinates a and b, wherein the second solved image comprises a corresponding pixel value S′(x) at coordinate x, wherein the first solved image comprises pixel values LS(a) and LS(b), and wherein a difference between S′(x) and I(x) is determined by the following equation: S ′ ⁡ ( x ) - I ⁡ ( x ) = x - a b - a ⁢ ( LS ⁡ ( b ) - I ⁡ ( b ) ) + b - x b - a ⁢ ( LS ⁡ ( a ) - I ⁡ ( a ) ) .