image processing An image is a visual representation of something. It can be two-dimensional, three-dimensional, or somehow otherwise feed into the visual system to convey information. An image can be an artifact, such as a photograph or other two-dimensiona ...

computer graphics Computer graphics deals with generating images with the aid of computers. Today, computer graphics is a core technology in digital photography, film, video games, cell phone and computer displays, and many specialized applications. A great de ...

, and

photography Photography is the art, application, and practice of creating durable images by recording light, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is employed ...

, exposure fusion is a technique for blending multiple exposures of the same scene (

bracketing In photography, bracketing is the general technique of taking several shots of the same subject using different camera settings. Bracketing is useful and often recommended in situations that make it difficult to obtain a satisfactory image with ...

) into a single image. As in

high dynamic range imaging In photography and videography, multi-exposure HDR capture is a technique that creates extended or high dynamic range (HDR) images by taking and combining multiple exposures of the same subject matter at different exposure levels. Combining mu ...

(HDRI or just HDR), the goal is to capture a scene with a higher dynamic range than the camera is capable of capturing with a single exposure.

Technique

By using different exposure parameters on the same scene, a wider dynamic range can be represented and later merged into an image with better dynamic range. After correcting for small shifts that may inadvertently happen with hand-held devices, the full-image can be fused in two ways: * A higher dynamic range raw image can be reassembled and tone-mapped like usual HDR images, or more commonly: * A blended image can be directly produced without reconstructing a higher bit-depth. The former method assumes a linear response from the camera, which may be provided by DNG or other raw formats. Some variants can take developed images, but the process of reconstructing the intensities is complicated and noisy, compromising the effective dynamic range. The latter method ertens-Kautz-Van Reeth (MKVr)only cares about aligning features and taking the best parts, automatically (by contrast, saturation, and proper exposure) or manually, so it is immune to this drawback. However, it cannot be considered a true HDR technique because no HDR image is ever created. The image does look better on displays, but the resulting bit depth of the image is equal to the input depth, unlike on a true HDR image where a greater bit depth allows storing more detailed intensity changes. Flexibility being its strength, this method can be extended to perform

focus stacking Focus stacking (also known as focal plane merging and z-stacking or focus blending) is a digital image processing technique which combines multiple images taken at different focus distances to give a resulting image with a greater depth of fiel ...

by using contrast as the sole criteria.

In photomicrography

In photomicrography, the exposure fusion is often the only way to acquire properly exposed images from stereomicroscopes. One of the software solutions designed for photomicrography is th
HDR module for QuickPHOTO microscopy software
This module can be also combined wit
Deep Focus

module to solve another problem, which is shallow depth of field of stereomicroscopes.

Software

* Enfuse

Notes

References

{{Reflist

External links

Enfuse
an open-source software for HDR fusion. Part of

Hugin Hugin may refer to: * Bob Hugin (born 1954), American politician and businessman * Hugin (longship), a Danish reconstruction of a Viking longship on display in Ramsgate, England * HUGIN, a widely used tool for uncertain reasoning using Bayesian net ...