HDR images with Elphel cameras

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The purpose of this project is to get HDR images using an Elphel camera.

For informations about HDR imaging see: Wikipedia.org. For informations about HDR imaging algorithms see: Debevec.org and Columbia.edu.


In computer graphics and photography, high dynamic range imaging (HDRI) is a set of techniques that allows a greater dynamic range of exposures than normal digital imaging techniques. The intention of HDRI is to accurately represent the wide range of intensity levels found in real scenes ranging from direct sunlight to shadows.

One HDR image is composed by many LDR (Low Dynamic Range) images representing the same scene. Ideally the LDR images should be acquired at the same time but usually they are acquired in sequence by the same camera as fast as possible. To avoid HDR ghost artifacts and to obtain high frame rate HDR videos it's important to have a high-performance hardware available depending on the static nature of the scene.

In order to get a HDR image, the HDRI system executes the following steps:

1. acquisition of n LDR images with different exposure time;

2. computation of the n acquired images;

3. generation of the HDR image.

The features of the HDRI system needed to execute this cycle are:

1. camera exposure time must vary during the acquisition process;

2. a memory to temporary save the acquired images;

3. a quite powerful CPU for image computation.

An Elphel camera satisfies all these requirements and can execute HDRI algorithms in different ways.


(under development)

Using parsedit.php you can request images with altered exposure times as show in this example: http://community.elphel.com/pictures/8.0/9images.html