Modifications and manipulations to an image stored, for example, in a computer memory, are often made to improve, change, modify the appearance of or otherwise manipulate a scene depicted in the image. For example, dynamic range compression algorithms are typically used to adjust image intensity such that a dark image can be brightened for a more aesthetically pleasing display. Gamma correction is an industry standard dynamic range compression method for brightening an image for display on a monitor or in print. According to the standard, an image is adjusted such that for each pixel in the image, the intensity is measured on a scale of 0 to 1, and the brightened intensity is equal to the original intensity raised to a power of (1.0/gamma), where gamma is a value greater than or equal to 1.0. Gamma correction brightens all pixels some amount irrespective of illumination. Like other forms of dynamic range compression, gamma correction brightens shadows without making them more similar in color to the color correct unshaded counterparts, and thus distorts the image appearance.
A challenge in the utilization of computers to accurately and correctly perform operations relating to images is the development of algorithms that truly reflect and represent physical phenomena occurring in the visual world. When utilizing conventional techniques for image modification, as for example, a gamma correction, unacceptable distortion of image characteristics, such as color, often occurs. Moreover, many manipulations of an image ignore the fact that the results of a desired change, such as, for example, a change in the geometry of a scene, affects illumination aspects of the image differently than material aspects. Accordingly, there is a persistent need for the development of accurate and correct techniques that can be utilized in the operations of computers relating to images, to provide improved image appearance, such as, for example, a more accurately correct color, image intensity adjustment or more versatility for a user to manipulate or modify an image.
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