Image Fusion

Image fusion is a key part of computational photography, in iOS often referred to as Smart HDR. It is a process that automatically combines multiple images into a single high-quality image, improving the dynamic range and sharpness, reducing noise and enhancing the overall quality.

This image fusion process is applied in the exposure modes A/M/Sl by default.

In automatic A mode, all lenses are active at the same time, which enables Multi-Lens Fusion. Through this technique, images from all the contributing lenses are merged, incorporating additional lens data into the final photo, potentially yielding more refined images.

In manual M mode or semi-automatic SI mode you can disable Image Fusion by disabling Smart HDR or by selecting an Unprocessed Capture Quality.

Multi-Lens & Single-Lens image fusion:

In automatic A mode, a white outline around the Lens Selector indicates all lenses being active, which enables Multi-Lens Fusion and fast lens switching.

In manual M mode or semi-automatic SI mode, a blue outline around the highlighted single lens-button indicates the currently active lens.

Control amount of Image Fusion with Capture Quality setting:

On the newest iPhones, the highest level of image processing is known as Deep Fusion, which utilizes advanced machine learning to analyze the photos pixel-by-pixel, thus providing exceptional levels of detail. ProCamera allows you to choose a more natural level of processing strength. For details on controlling the amount of Image Fusion, including turning it off, see our Capture Quality article.

Bayer RAW format does not support image fusion, as it is defined as "unprocessed sensor data", which can also be described as a single sensor read-out.