Mapping a low resolution, noisy tone mapping operation onto high resolution images

An electronic device comprising:

• a memory storing image data;
• and
• at least one processing device configured to:
• convert at least one raw image frame to a first image at a first resolution and a second image at a second resolution, wherein the second resolution is lower than the first resolution;
• apply tone mapping to the second image to derive a third image at the second resolution;
• perform histogram matching and regularization using the second image and the third image to determine a lookup table approximating histogram matching of the second image to the third image;
• derive a global gain map for tone mapping based on luma for the first image and the lookup table;
• derive a local gain map by up-sampling and denoising residual differences between the third image and the lookup table applied to the second image after regularization of the lookup table;
• and
• based on the global gain map and the local gain map, determine a total gain map for tone mapping the first image to produce a fourth image at the first resolution.

A non-transitory machine-readable medium containing instructions that when executed cause at least one processor to:

• convert at least one raw image frame to a first image at a first resolution and a second image at a second resolution, wherein the second resolution is lower than the first resolution;
• apply tone mapping to the second image to derive a third image at the second resolution;
• perform histogram matching and regularization using the second image and the third image to determine a lookup table approximating histogram matching of the second image to the third image;
• derive a global gain map for tone mapping based on luma for the first image and the lookup table;
• derive a local gain map by up-sampling and denoising residual differences between the third image and the lookup table applied to the second image after regularization of the lookup table;
• and
• based on the global gain map and the local gain map, determine a total gain map for tone mapping the first image to produce a fourth image at the first resolution.