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paper
information
abstract
We present a novel approach that allows users to intuitively and
interactively manipulate High Dynamic Range (HDR) images using
commonly available Low Dynamic Range (LDR) displays. This solves
the problem of how to draw with contrasts that are much larger than
the monitor can display. Whereas commercial HDR-enabled drawing
programs manipulate tone mapped representations of HDR images, we
provide an intuitive brush interface that supports interaction with
the unmapped HDR imagery. Our approach introduces two new brush
constructs to a typical virtual painting interface, such as Adobe
Photoshop. First, we present a brush that locally adjusts the
display of the HDR image to a dynamic range specified within a
real-time, interactive, local histogram of the region around the
cursor. This affords precise, quantitative control of the HDR
contrast values produced by the brush. Second, we demonstrate a
brush that uses the perception of glare as the underlying basis for
determining the contrasts painted onto the HDR image, giving
artistic control over the HDR contrasts. By maintaining an HDR
image, the result is available for further manipulation and
processing by algorithms, such as those used in image-based
rendering, for which an LDR representation is inadequate. Finally,
we use the Graphics Processing Unit to provide real-time visual
feedback for the effects of each image manipulation.
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figures
Figure 1: Quantitative HDR Painting Interface.
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In the upper left, a hue and saturation
selector, and in the center and inset is the brush interface that moves
with the cursor. In the histogram, the entire luminance domain
is visualized and the user selects the luminance associated with the selected
hue and saturation values. The highlighted area of the histogram represents
the visualized luminance range in which the region within the outer ring is
linearly compressed and displayed.
The inner ring represents the region that will be painted by the brush.
Background image courtesy of Paul Debevec.
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Figure 2: Interface
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On the left, the memorial church modified via the quantitative
controls. The luminance value for the color is selected within
the histogram and is denoted by the purple bar. The peak in the
histogram around the purple bar results from the painted region
being modified by the selected luminance value.
The region around the cursor also linearly compresses the luminance
values between 28.6 cd/m^2 and 0 cd/m^2 to visualize the dynamic
range selected in the highlighted region of the histogram.
On the right, an example of the interactive scaling visualization
within our interface.
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Figure 3: Glare Brush
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Three different inner radii and their resulting glare effects.
As the inner radius decreases and the glare effect increases,
the dynamic range of the luminance expands as seen in the
respective histograms.
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university of central florida : graphics group |
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