Tone mapping is a technique used in image processing and computer graphics to map one set of colors to another to approximate the appearance of high-dynamic-range images in a medium that has a more limited dynamic range.
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17 Facts About Tone mapping
2.
Inverse tone mapping is the inverse technique that allows to expand the luminance range, mapping a low dynamic range image into a higher dynamic range image.
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3.
Gamut Tone mapping algorithms were extensively studied in the context of color printing.
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4.
Several tone mapping operators were developed to map high dynamic range images to standard displays.
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5.
Goals of tone mapping can be differently stated depending on the particular application.
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6.
Simple example of global tone mapping filter is, where Vin is the luminance of the original pixel and Vout is the luminance of the filtered pixel.
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7.
An even more sophisticated group of tone mapping algorithms is based on contrast or gradient domain methods, which are 'local'.
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8.
Examples of such tone mapping methods include: gradient domain high dynamic range compression and A Perceptual Framework for Contrast Processing of High Dynamic Range Images .
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9.
The key concept of this tone mapping method is a decomposition of an HDR image into areas of consistent illumination and the local calculation of the lightness values.
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10.
One simple form of tone mapping takes a standard image and applies unsharp masking with a large radius, which increases local contrast rather than sharpening.
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11.
One of the commonly used tone mapping algorithms is the iCAM06 which is based on both the color appearance model and hierarchical mapping.
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12.
In some cases local tone mapping is used even though the dynamic range of the source image could be captured on the target media, either to produce the distinctive appearance of a locally tone mapped image, or to produce an image closer to the photographer's artistic vision of the scene by removing sharp contrasts, which often look unattractive.
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13.
However, when tone mapping is applied to a single exposure in this way, the intermediate image has only normal dynamic range, and the amount of shadow or highlight detail that can be rendered is only that which was captured in the original exposure.
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14.
One of the original goals of tone mapping was to be able to reproduce a given scene or image onto a display device such that the brightness sensation of the image to a human viewer closely matches the real-world brightness sensation.
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So, the results of local tone mapping are often judged as perverting the nature of a documentalist photographic image and far from photographic realism.
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16.
Tone mapping can produce distinctive visual effects in the final image, such as the visible halo around the tower in the Cornell Law School image below.
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