Method and apparatus for controlling signal-to-noise ratio (SNR) in high dynamic range automatic exposure control imaging are disclosed. In the method and apparatus, image data is received and a shadow threshold is determined based on the image data. Further, a respective threshold integration ratio is determined for each merge transition of a plurality of exposures having a respective plurality of exposure times. The threshold integration ratio is determined based on a threshold SNR for the merge transition. In the method and apparatus, an integration ratio for each merge transition is determined based on the shadow threshold and the threshold integration ratios. An output image is generated based on the determined integration ratios for each merge transition.