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Introduction to High Dynamic-Range Images

High dynamic-range imaging (HDRI) permit a far greater dynamic range of exposures (i.e. a large difference between light and dark areas) than normal digital imaging techniques. HDRI accurately represents the wide range of intensity levels found in real scenes ranging from direct sunlight to the deepest shadows.

Enabling HDRI in ImageMagick

By default image pixels in ImageMagick are stored as unsigned values that range from 0 to the quantum depth which is typically 16-bits (Q16). With HDRI enabled the pixels are stored in a floating-point representation and can include negative values as well as values that exceed the quantum depth. A majority of digital image formats do not support HDRI so any pixels outside the quantum range are clamped before they are stored. For HDRI the OpenEXR delegate library is required. Download and install the library and configure ImageMagick as follows:

  ./configure --enable-hdri

Note, HDRI support within ImageMagick is considered experimental.