Welcome to McCann Imaging
Mary and John McCann
We work on imaging research in microscopy and color vision.
Vision Research
Scientific Meetings and Papers:
2009 Google, Jan 22, Mountain View, CA
http://www.mefeedia.com/entry/hdr-and-color-constancy-new-psychophysical-results/14002228
2008 Google, Jan 25, Mountain View, CA
<http://youtube.com/watch?v=ALfiTDYLtAQ&feature=user>
2009 Electronic Imaging, San Jose
C. Parraman, A. Rizzi & J. J. McCann,
“Separating the effects of glare from simultaneous contrast in HDR images”, 6806-9
J. J. McCann & A. Rizzi,
“Preservation of Edges: The Mechanism for Improvements in HDR Imaging”,
J. J. McCann,
“Adaptation... What adaptation?”, 7241-23
In almost ever conversation with vision scientist one hears the statement “ the eye adapts…”. Always, this statement is true. The problem is that there are so many ways that the visual system “adapts’ that the words have no meaning. The visual system exhibits chemical dark-adaptation, neural light-adaptation, diurnal melatonin-adaptation, pupil adaptation, chromatic adaptation, von Kries adaptation, Blakemore spatial-frequency adaptation, McCulloch colored-stripe adaptation and many more kinds of adaptation. All neurons adapt. There are more than 106 retinal receptors that adapt, and potentially 1010 cortical neurons that adapt. What do we mean when we say “the eye adapts”?
Keywords: vision, adaptation, dark adaptation, light adaptation, melatonin adaptation, pupil adaptation, chromatic adaptation, von Kries adaptation, spatial-frequency adaptation, McCulloch adaptation.
John J. McCann and Alessandro Rizzi,
“Retinal HDR Images: Intraocular Glare and Object Size”
Proceedings of the Color Imaging Conference, Portland, CIC 16, 24, 2008.
November, 2008
A. Rizzi & J. J. McCann, “Simultaneous Contrast and Intraocular Glare:
Opposing Image Dependent Mechanisms in Appearance”, 2008.
J. J. McCann, “Color Matches in Dim Narrow-band Illumination”, 2008.
2008 CGIV Terrassa, Spain
J. J. McCann & A. Rizzi, “Appearance of High-Dynamic Range Images in a Uniform
.Lightness Space”, pp. 177-181, 2008.
2008 Electronic Imaging, San Jose
A. Rizzi, M. Pezzetti, & J. J. McCann,
“Separating the effects of glare from simultaneous contrast in HDR images”, 6806-9
J. J. McCann,
“Perceptual rendering of HDR in painting and photography” 6806-30
J. J. McCann,
“Color gamuts in dim illumination” 6807-2
2007 CIC, Albuquerque, NM
J. J. McCann
“Colors in Dim Illumination and Candlelight”
A. Rizzi, M. Pezzetti, and J. J. McCann
“Glare-limited Appearances in HDR Images”
2007 CREATE, Bristol
J. J. McCann
“The Interaction of Art, Technology and Consumers in Pictures Making”
2007 ECVP, Arezzo
J. J. McCann
Rod – Lcone color matching in complex images
Rod and L-cone interactions generate color appearances. This paper measure these appearances in complex scenes above and below-M and S-cone thresholds. The test target was a ColorChecker viewed in tungsten light and 1 wax candle. Firelight is an ideal illuminant for Rod-Lcone color. The observers’ task was to adjust RGB digits in LCD computer display to match the appearance of the ColorChecker. With the tungsten illumination, above L-,M-,& S-cone thresholds, the L*a*b* values for the reflective ColorChecker and the emissive LCD were reasonably close. With 1 candle illumination, the below M- and S-cone threshold ColorChecker showed matches marked different in L*a*b* values. A 4-D color space is not required because all colors were matched to above cone threshold colors, sharing information with other color channels. The color appearances are not consistent with rods sharing S-channel alone, or M-channel alone. The colors are not consistent with the rods desaturating all three channels. Under these conditions, the colors are consistent with the rod spatial comparisons sharing both the M- and the S-cone channels.
A. Rizzi, M. Pezzetti, J.J. McCann,
Measuring the visible range of High Dynamic Range Images (HDRI)
We made pairs of identical film transparencies. We viewed one (single-contrast), then two superimposed in registration (double-contrast). Single-contrast images have 2.7 log 10 dynamic range; double contrast 5.4 log10 range. Observers estimated the appearance of 40 gray areas surrounded with various size white and black blocks. First, the surround had equal white and black areas (average single-contrast luminance=50.01%max) and (double-contrast=50.00%max). Doubling the contrast had minimal effect on retinal glare. Magnitude estimates show nearly the same plot (appearance vs. log luminance) for both contrasts in the range of 0.0 to 2.3OD, and no discrimination at higher optical densities. Second, with a (8%white&92% black) surround appearances covered 0.0 to 2.7. Increasing the stimulus range had little effect on appearance. Decreasing the surround’s white area, decreased veiling glare and increased the range of usable densities. These, and other experiments, measure how veiling glare controls the range of appearance in HDRI.
INVITED PAPERS
J. J. McCann, “Art Science and Appearance in HDR images”, J. Soc. Information Display, vol. 15(9), 709-719, 2007.
J. J. McCann and A. Rizzi, (2007) “Camera and visual veiling glare in HDR images”, J. Soc. Information Display, vol. 15(9), 721-730, 2007.
2007 IMQA, Chiba
J. J. McCann, A. Rizzi,
“Spatial Comparisons:
The Antidote to Veiling Glare Limitations in Image Capture and Display”
2007 IMQA Lecture, Chiba
Large .pdf file = 43 MB
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2007 Electronic Imaging, San Jose
A. Rizzi, J. J. McCann,
“On the Behavior of Spatial Models of Color”
J. J. McCann, A. Rizzi,
“Veiling glare: the dynamic range limit of HDR images”
J. J. McCann,
“Aperture and Object Mode Appearances in Images”
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2006 Color Imaging Conference
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2006 ADEAC (SID/VESA)
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2006 European Conference on Visual Perception (ECVP) papers
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links:
paper list
Microscopy