How does high dynamic range work?

A high dynamic range photograph of a ruined castle

A good example of high dynamic range

In photography, high dynamic range (HDR) is a set of techniques that allow a single image to gain a greater dynamic range between the lightest and darkest parts of the subject. This is a desirable process as standard shots tend to produce blownout highlights and/or flat shadows, damaging the overall quality of the picture.

High dynamic range works by taking multiple shots at varying exposure levels whenever the user pulls the trigger, before merging these shots together into a single RAW image file (a type of unprocessed file that can be heavily adjusted through editing software before being converted to a positive file format such as a TIFF or a JPEG). This hybrid image not only takes the best elements from each shot – revealing intricate highlight and shadow details – but also improves image detail due to removing the undesirable effects of ‘lossy compression’ (a process of data shredding when producing a JPEG image to reduce its overall file size).

Dynamic range is measured in exposure value (EV) stops between the brightest and darkest parts of any image. By increasing the exposure value by one stop, for instance, the amount of light across the image is doubled. As such, modern high-end cameras come with an auto exposure bracketing feature as standard, offering dynamic range levels up to 18 EV to ensure greater detail across all areas of any image.

Answered by HIW.