Recent Talks

John McCann, McCann Imaging (United States)


“What we see and what we know: Partners in human vision”

17 Darkside talkf.pdf



Polaroid Retiree Association

Mary and John McCann

“Stories from behind the curtain at Polaroid’s Shareholders Meetings”

October 19, 2016

Every spring in 1970’s, all parts of Polaroid converged on a warehouse to put together the Annual Shareholders Meeting. 

Many important products, steeped in both technology and art, came out of those meetings.  In some years, they merged into employee meetings for the entire company.  There are many great stories caused by the annual collision of all the different parts of the company around the stage in the warehouse.

Mary and John got to meet, and become good friends with, a very wide cross-section of the wonderful people that made Polaroid.

PRAf2 Slides copy.pdf


John  McCann,

”Rendition techniques for HDR Scenes in Painting, Photography, and Electronic Imaging”,

Proc. ICIP, Phoenix, (2016).

ICIP 2016.pdf


Vision and Visual Optics (ViVO)

John McCann

“Constancy in Natural Scenes: How Neural Contrast cancels Glare”


Schepens 4 13 16.pdf


Retinex at 50

Joint Session of Color and Human Vision

Electronic Imaging

John McCann

“Retinexes Algorithms:

Many spatial processes used to solve many different problems”

McCann Proc RET50.pdf or link IS&T

EI16 Slides.pdf

J. McCann

“Retinex at 50: Color Theory and Spatial Algorithms, A Review”

  1. J.Electronic Imaging, “Retinex at 50”, (2017)   Draft

17JEI Retinex50.pdf


American Chemical Society Memorial

Edwin H. Land

MIT Museum

August 14, 2015

MIT Museum F2.pdf

94Land's Images.pdf


November, 2014

Color Science in Boston”

Proc. IS&T Color Imaging Conference, 22, in press, Boston (2014)

November 7, 2014

McCann CIC22f.pdf

Retinex Workshop”

November 7, 2014

Retinex Workshop Nov 7 2014.doc


“High-Dynamic-Range Imaging: Capture, Rendition and Applications

November 4, 2014

14 CIC HDR Tutorial T5C.pdf

February, 2014

John J. McCann,

ColorChecker® at the beach: Dangers of sunburn and glare

Proc. SPIE, 9015-31, 2014.


October 25, 2013       Lightness: The cancelation of two powerful spatial mechanisms




November, 2013

John J. McCann, McCann Imaging, Belmont, USA;

Vassilios Vonikakis, Advanced Digital Sciences Center, Singapore;

Cristian Bonanomi, and Alessandro Rizzi, University of Milan, Italy

Chromaticity limits in color constancy calculations

Proc. IS&T Color Imaging Conference, 21, in press, Albuquerque (2013)



January, 2013

John J. McCann,

Spatial Imaging in Color and HDR: Prometheus Unchained

Proc. SPIE, 8652-7, 2013.


November, 2012

John J. McCann,

CIC@20: The continuing "Tale of Two Paradigms

Proc. IS&T/SID Color Imaging Conference, 20, 21-29, (2012)

12 CIC20.pdf

Sept, 2012

48 Color 3D Mond.pdf

92 Ret image .pdf

“Ansel Adams Zone System:

Techniques for rendering HDR scenes on LDR film media”

J.J. McCann, A. Rizzi

The Ansel Adams Zone System, first described in 1949, was a two-step process that described techniques for scene capture and spatial manipulation of the rendered image [Adams, 1981]. The exposures of the film negative was calculated from spot-photometer scene measurements that determined the scene range.  That range determined both the camera exposure and the development procedure in order to capture the entire scene range in the negative. Prints have a very limited range, so spatial dodging and burning techniques compressed the scene information into the rendition range. This work describes the Adam's Zone System and the parallel process of our human vision system to capture dynamic range of natural scenes. In particular the work focuses on the parallels with the High-Dynamic Range (HDR) rod/cone response and the LDR range of ganglion cells. Both the Zone System and human vision underline the important distinction of actual and apparent dynamic range of luminance.

May, 2012

John J. McCann and Vassilios Vonikakis,

Accurate Information vs. Looks Good:

  Scientific vs. Preferred Rendering

Proc. CGIV, 2012.


January, 2012

John J. McCann,

The general solution to HDR imaging

Proc. SPIE, 8191-60, 2012.

12 EI 8291-60.pd

John J. McCann,

Paintings, photographs, and computer graphics

are calculated appearances

Proc. SPIE, 8191-36, 2012.

12 EI 8291-36f.pdf

John J. McCann,

Color Assimilation and Contrast near Absolute Threshold

Proc. SPIE, 8192-2, 2012.

12EI rodColor.pdf

November, 2011

John J. McCann,

“Appearance at the low-radiance end of HDR vision:

Achromatic & Chromatic”

Proc. IS&T/SID Color Imaging Conference, 19, 186-190, (2011)

11 CIC rodColor.pdf

                                                    November 12, 2011

                                                    John J. McCann,

                                           “Digital Color Separations”

                                                    ISCC/IS&T/SID Special Topic Meeting:

                                                    Revisiting Color Spaces, November 12, (2011).)

                                 11 CIC rodColor.pdf

John J. McCann,

“HDR imaging and color constancy: Two sides of the same coin?”

Proc. SPIE, 7866-25, 2011.

11 EI7866-25.pdf

November, 2010

John J. McCann, Vassilios Vonikakis, Carinna E. Parraman

and Alessandro Rizzi,

“Analysis of Spatial Image Rendering”

Proc. IS&T/SID Color Imaging Conference, 18, 2010


2010 Electronic Imaging, San Jose

John McCann,

“The Ansel Adams Zone System: Chemical HDR Capture and Range Compression”

We tend to think of digital imaging and the tools of Photoshop as a new phenomenon in imaging.  We are familiar with multiple-exposure HDR techniques intended to capture a wider range of scene information, and tone-scale adjustments to make better pictures.  We tend to think of everyday, consumer, silver-halide photography as a fixed window of scene capture with a limited, standard range of response.  This idea of silver-halide photography is certainly true of the instant films, and the negative films processed at the drug store, that were most popular between 1950 and 2000. These systems had fixed dynamic range and fixed tone-scale response to light.  That response was constant for all pixels in the film image.

The  Zone System was formulated  in 1941 by Ansel Adams along with Fred Archer.  It was earlier than the billions of consumer photos in the second half of the 20th century, yet it was much more sophisticated than today's digital techniques.  This talk will describe the chemical mechanisms of the zone system in the parlance of digital image processing.  It will describe the Zone System's chemical techniques for image synthesis.  Although current HDR imaging shares some of the Zone System's achievements, it usually does not achieve all of them.

Proc. SPIE, 7527-28, 2010.


Carinna Parraman

Centre for Fine Print Research, University of the West of England, Bristol, BS3 2JT

“The drama of illumination:

artist’s approaches to the creation of HDR in paintings and prints”

For many centuries artists have considered and depicted illumination in art – from the effect of sunlight on objects at different times of the day, of shadows and highlights as cast by the moon, through indirect light as that through an open window or the artificial light of the candle or firelight. 

The presentation will consider artists who were fascinated by the phenomena of natural and artificial illumination and how they were able to render the natural world as a form of high dynamic range through pigment. Artists have been long aware of the psychological aspects of the juxtaposition of colour in exploiting the optical qualities and arranging visual effects in painting and prints. Artists in the 16th century were attempting to develop an extended dynamic range through multi-colour, wood-block printing. Artists working at the height of naturalist realism in the 17th and 18th century were fascinated by the illusory nature of light on objects. The presentation will also consider the interpretation of dynamic range through the medium of mezzotint, possibly the most subtle of printing methods, it was used by printers to copy paintings, and to create highly original works of art containing a wide dynamic range of tones. 


Carinna E. Parraman, John J. McCann, Alessandro Rizzi,

Artist's colour rendering of HDR scenes in 3D Mondrian colour-constancy experiments”,

The presentation provides an update on ongoing research using three-dimensional Colour Mondrians. Two still life arrangements comprising hand painted coloured blocks of 11 different colours were subjected to two different lighting conditions of a nearly uniform light and a directed spotlights. The three-dimensional nature of these test targets adds shadows and multiple reflections, not found in flat Mondrian targets. Working from exactly the same scene, the second experiment involved the use of watercolour inks and paints to recreate both LDR and HDR Mondrians on paper. A second set of appearance measurements of both scenes were made. Here we measured appearances by measuring reflectances of the artist’s rendering. Land’s Colour Mondrian extended colour constancy from a pixel to a complex scene.  Since it used a planar array in uniform illumination, it did not measure the appearances of real life 3-D scenes in non-uniform illumination.  The experiments in this paper, by simultaneously studying Low Dynamic Range (LDR) and High Dynamic Range (HDR) renditions of the same array of reflectances, extend Land’s Mondrian towards real scenes in non-uniform illumination.

Proc. SPIE, 7528-1, 2010.

Parraman 7528-01.pdf


John J. McCann, Carinna E. Parraman, Alessandro Rizzi,

“Pixel and spatial mechanisms of color constancy”,

Color constancy remains an important subject of research on color standards, computer imaging, and human color vision.  There are many different theories and algorithms that interpret and predict constancy.  This paper analyzes three different approaches that are frequently discussed separately in the literature: pixel-based colorimetric standards of appearance; computer imaging calculations of an object’s reflectance; and calculation of appearance using spatial comparisons.  This paper compares and contrasts these approaches.  Further, it reviews experiments that measure appearance in color constancy in a variety of situations.  A pivotal tool in analyzing models of constancy is the correlation of object’s reflectance with appearance.  Each approach has different interpretation of this correlation.  Using measurements of constancy with particular attention to reflectance, illumination, and appearance helps us to see the successes and limitations of each constancy approach.

Proc. SPIE, 7528-1, 2010.

McCann 7528-02.pdf


John J. McCann,

The appearance of illusions in the delusion of reality”,

Physicists born in the 17th century still influence our impressions of reality.    Take for example, the work at the Royal Institution, London around 1800.  Sir Humphrey Davy and Josiah Wedgwood developed a precursor to silver-halide photography.  Thomas Young taught at the Royal Institution at the time and proposed that three types of retinal receptors at the same location could explain our color response to all visible wavelengths.  It is tempting to think that vision behaves the same as silver-halide film.  We tend to think that the response of a single pixels can successfully model the response to the entire image, with curious exceptions, that we call illusions.  

However, by 1800 there were the shrewd observations of da Vinci, von Guericke, Count Rumford, and many others.  They showed that vision was different from film.  All the neurophysiology of the second half of the 20th century has shown the visual pathway is a sequence of spatial operators.  The pixel model of vision is a delusion.  

We need to free our thinking from the pixel models of these physicists.  If we look at a display, we apply our spatial image-processing pathway to the image on our retinas.  Our spatial transforms of targets is the reality of vision.

Proc. SPIE, 7528-31, 2010.

10 DarkSide.pdf


J. J. McCann, A. Rizzi,

Retinal HDR images: Intraocular glare and object size”

Journal of the SID 17/11, 913-920, 2009.


                                          A. Rizzi, J. McCann,

                                                  Glare-limited appearances in HDR images

                                                   Journal of the  Journal of the SID 17/1,3,12,  2009.




November, 2009

J. J. McCann, C. E. Parraman and A. Rizzi,

“Reflectance, Illumination and Edges

Proc.Color Imaging Conference, Albuquerque, CIC 17, (2009).

09CIC 3DMond.pdf

October 1, 2009.

J. J. McCann, C. E. Parraman and A. Rizzi,


Proc. 2009 Association Internationale de la Couleur 11th Congress, Sidney, 2009.


September, 11, 2009

Exloring the Limits of HDR Capture
Workshop Moderator: Ricardo Motta, Pixim
John McCann, McCann Imaging

Dick Lyon, Google
Howard Rhodes, Omnivision
David Cardinal, CardinalPhoto

2009 Electronic Imaging, San Jose

C. Parraman, A. Rizzi & J. J. McCann,

Colour Appearance and Colour Rendering of HDR Scenes: An Experiment”,

Proc. SPIE, 7241-26


J. J. McCann & A. Rizzi,

“Preservation of Edges: The Mechanism for Improvements in HDR Imaging”,

Proc. SPIE, 7241-27


J. J. McCann,

“Adaptation... What adaptation?”,

Proc. SPIE, 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”

Proc. Color Imaging Conference, Portland, CIC 16, 24, 2008.

  1. A.Rizzi & J. J. McCann,

“Simultaneous Contrast and Intraocular Glare: Opposing Image Dependent Mechanisms in Appearance”,


  1. J.J. McCann,

“Color Matches in Dim Narrow-band Illumination”,

Proc. Color Imaging Conference, Portland, CIC 16, 24, 2008.


2008CIC Age.pdf

2008 CGIV Terrassa, Spain

  1. J.J. McCann & A. Rizzi,

“Appearance of High-Dynamic Range Images in a Uniform Lightness Space”,

Proc CGIV,Barcelona, 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

08EI Rizzi 6806-09.pdf

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.