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Apple files patent for single-exposure HDR photos

A patent originally filed by Apple in June 2012 details a method of generating HDR photos by using a single exposure.

A patent originally filed by Apple in June 2012 details a method of generating high dynamic range (HDR) photos by using a single exposure.

(Credit: Apple)

HDR imaging has become increasingly popular amongst manufacturers and photographers who want to boost the dynamic range of their images to better display variances in shadow and highlight detail. Usually to make an HDR image, the photographer needs to take several exposures and stitch them together in post-processing.

A patent filed by Apple and discovered by the Image Sensors World blog details a process whereby an HDR image can be created from a single photo. Problems that can arise from the traditional multiple-exposure method include ghosting and shifting subjects — unless you are able to hold the camera or phone particularly still or use a tripod.

Apple has already had an HDR mode available in the camera module for a while, though it combines three separate exposures using the traditional method.

A diagram from Apple's patent filing that shows an image sensor with the HDR capability. (Screenshot by CBSi)

This new patent outlines how the device can scan the same row of pixels multiple times. The data is then combined to create the HDR image. This method would mitigate any possibility of ghosting and motion blur from combining multiple exposures.

A similar patent has previously been filed by Canon, which also shows how a single photo could be used to make an HDR image. The Canon method appears to work slightly differently, by adjusting exposure on a pixel-by-pixel basis.