Campus Event Calendar
Event Entry
What and Who
Evaluation and Enhancement of HDR Image Appearance on Displays of VaryingDynamic Range
Akiko Yoshida
Max-Planck-Institut für Informatik - D4
Promotionskolloquium
AG 1, AG 2, AG 3, AG 4, AG 5, SWS, RG1, MMCI
Public Audience
English
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Date, Time and Location
Tuesday, 16 December 2008
16:00
90 Minutes
E1 4
019
Saarbrücken
Abstract
The increasingly widespread availability of high dynamic range (HDR)
technology has led to active study of the characteristics of the human
visual system (HVS) in terms of brightness, lightness, contrast, and color
perception and the application of the results of these studies to computer
graphics. Because the development of HDR technology gives us display
devices with much broader dynamic range for both high and low luminances,
it is especially important to revise the models of HVS for the luminance
ranges which are not covered by classical psychophysics, but required by
the new HDR technology.
In this dissertation, we focus on the evaluation and enhancement of the
appearance of HDR images as reproduced on low dynamic range (LDR) media.
First, we conducted a psychophysical experiment on seven tone mapping
operators (TMOs) to assess how tone mapped images are perceived
differently by human observers and to find out which attributes of image
appearance account for these differences. The results show qualitative
differences in TMOs, however, it also turned out that it was hard to
choose the consistently best algorithm in terms of the fidelity of tone
mapped images to real-world scenes. Based on this result, we conducted
another series of psychophysical experiments with a generic easy to
understand TMO. This experiment focused on three parameters - brightness,
contrast, and color saturation - in order to measure user preference for,
and fidelity of, tone
mapped HDR images across several types of emulated limited dynamic range
displays. The results of this study provide novel guidance for creating
more advanced TMO designs.
To evaluate the enhancement of image appearance, we conducted two series of
experiments on contrast and brightness enhancement. A non-linear change in
perceived contrast with respect to given physical contrast and a different
adaptation luminance levels were measured by contrast scaling and contrast
discrimination threshold experiments on HDR displays. These results lead
to a model of just noticeable difference (JND) unit which provides
uniformly changing perceived contrast in complex images. Finally,
brightness enhancement caused by the glare illusion was investigated. We
employed two profiles to evoke the glare illusion: a point spread function
(PSF) of the human eye and a Gaussian kernel. The outcome of this study
shows that the glare illusion increases the perceived luminance
(brightness) by 20 – 35% for both convolution methods of a PSF and a
Gaussian kernel. This means that faithful simulation of the human eye
optics, which has been proposed before, is not necessary to achieve a
strong brightness enhancement of the glare illusion because the Gaussian
kernel, which has no theoretical justification in human perception, evokes
the brightness enhancement at the same or higher strength than the PSF.
technology has led to active study of the characteristics of the human
visual system (HVS) in terms of brightness, lightness, contrast, and color
perception and the application of the results of these studies to computer
graphics. Because the development of HDR technology gives us display
devices with much broader dynamic range for both high and low luminances,
it is especially important to revise the models of HVS for the luminance
ranges which are not covered by classical psychophysics, but required by
the new HDR technology.
In this dissertation, we focus on the evaluation and enhancement of the
appearance of HDR images as reproduced on low dynamic range (LDR) media.
First, we conducted a psychophysical experiment on seven tone mapping
operators (TMOs) to assess how tone mapped images are perceived
differently by human observers and to find out which attributes of image
appearance account for these differences. The results show qualitative
differences in TMOs, however, it also turned out that it was hard to
choose the consistently best algorithm in terms of the fidelity of tone
mapped images to real-world scenes. Based on this result, we conducted
another series of psychophysical experiments with a generic easy to
understand TMO. This experiment focused on three parameters - brightness,
contrast, and color saturation - in order to measure user preference for,
and fidelity of, tone
mapped HDR images across several types of emulated limited dynamic range
displays. The results of this study provide novel guidance for creating
more advanced TMO designs.
To evaluate the enhancement of image appearance, we conducted two series of
experiments on contrast and brightness enhancement. A non-linear change in
perceived contrast with respect to given physical contrast and a different
adaptation luminance levels were measured by contrast scaling and contrast
discrimination threshold experiments on HDR displays. These results lead
to a model of just noticeable difference (JND) unit which provides
uniformly changing perceived contrast in complex images. Finally,
brightness enhancement caused by the glare illusion was investigated. We
employed two profiles to evoke the glare illusion: a point spread function
(PSF) of the human eye and a Gaussian kernel. The outcome of this study
shows that the glare illusion increases the perceived luminance
(brightness) by 20 – 35% for both convolution methods of a PSF and a
Gaussian kernel. This means that faithful simulation of the human eye
optics, which has been proposed before, is not necessary to achieve a
strong brightness enhancement of the glare illusion because the Gaussian
kernel, which has no theoretical justification in human perception, evokes
the brightness enhancement at the same or higher strength than the PSF.
Contact
Thorsten Thormählen
+49.681.9325.417
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Svetlana Borodina, 12/15/2008 14:54 -- Created document.