1. A method comprising: receiving a left input frame created with a first luminance range and a right input frame created with a second luminance range, the left input frame comprising a plurality of left input scanlines, the right input frame comprising a plurality of right input scanlines, each individual left input scanline in the plurality of left input scanlines corresponding to an individual right input scanline in the plurality of right input scanlines, and the first luminance range being different from the second luminance range; determining a first left input scanline in the plurality of left input scanlines and a first right input scanline in the plurality of right input scanlines, the first left input scanline corresponding to the first right input scanline, the first left input scanline comprising a first set of left input pixels, and the first right input scanline comprising a first set of right input pixels; selecting a first subset of left input pixels among the first set of left input pixels; selecting a first subset of right input pixels among the first set of right input pixels; computing, with the first subset of left input pixels and the first subset of right input pixels, first input scanline disparity between the first subset of left input pixels and the first subset of right input pixels; generating, based at least in part on the first input scanline disparity, a first left output scanline for a left high dynamic range (HDR) output frame and a first right output scanline for a right HDR output frame; wherein the first subset of left input pixels is selected, based on one or more criteria, from the set of left input pixels; wherein the one or more criteria comprise an upper luminance level and wherein zero or more pixels, in the set of left input pixels, that are above the upper luminance level are excluded from being included in the first subset of left input pixels.