Campus Event Calendar
Event Entry
What and Who
Contours and Contrast
M.Sc Kaleigh Smith
Max-Planck-Institut für Informatik - D4
Promotionskolloquium
AG 1, AG 2, AG 3, AG 4, AG 5, SWS, RG1, MMCI
Public Audience
English
Note: We use this to send email in the morning.
Date, Time and Location
Thursday, 11 December 2008
13:00
90 Minutes
E1 4
019
Saarbrücken
Abstract
Contrast in photographic and computer-generated imagery communicates colour and lightness differences that would be perceived when viewingthe represented scene.
Due to depiction constraints, the amount ofdisplayable contrast is limited, reducing the image's ability to accurately represent the scene. A local contrast enhancement
techniquecalled unsharp masking can overcome these constraints by addinghigh-frequency contours to an image that increase its apparent contrast. In three novel algorithms
inspired by unsharp masking, specialized local contrast enhancements are shown to overcome constraints of a limited dynamic range, overcome an achromatic palette,
and to improve the rendering of 3D shapes and scenes.
The Beyond Tone Mapping/approach restores original HDR contrast to its tone mapped LDR counterpart by adding high-frequency colour contours to the LDR image
while preserving its luminance. Apparent Greyscale is a multi-scale two-step technique that first converts colour images and video to greyscale according to their
chromatic lightness, then restores diminished colour contrast with high-frequency luminance contours. Finally, 3D Unsharp Masking performs scene coherent enhancement
by introducing 3D high-frequency luminance contours to emphasize the details, shapes, tonal range and spatial organization of a 3D scene within the rendering pipeline.
As a perceptual justification, it is argued that a local contrast enhancement made with unsharp masking is related to the Cornswillusion, and that this may explain its effect
on apparent contrast.
Due to depiction constraints, the amount ofdisplayable contrast is limited, reducing the image's ability to accurately represent the scene. A local contrast enhancement
techniquecalled unsharp masking can overcome these constraints by addinghigh-frequency contours to an image that increase its apparent contrast. In three novel algorithms
inspired by unsharp masking, specialized local contrast enhancements are shown to overcome constraints of a limited dynamic range, overcome an achromatic palette,
and to improve the rendering of 3D shapes and scenes.
The Beyond Tone Mapping/approach restores original HDR contrast to its tone mapped LDR counterpart by adding high-frequency colour contours to the LDR image
while preserving its luminance. Apparent Greyscale is a multi-scale two-step technique that first converts colour images and video to greyscale according to their
chromatic lightness, then restores diminished colour contrast with high-frequency luminance contours. Finally, 3D Unsharp Masking performs scene coherent enhancement
by introducing 3D high-frequency luminance contours to emphasize the details, shapes, tonal range and spatial organization of a 3D scene within the rendering pipeline.
As a perceptual justification, it is argued that a local contrast enhancement made with unsharp masking is related to the Cornswillusion, and that this may explain its effect
on apparent contrast.
Contact
Thorsten Thormählen
+49.681.9325.417
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Svetlana Borodina, 12/09/2008 14:03 -- Created document.