Parallel Error Diffusion Update

In January I wrote a post on parallel error diffusion. In the meantime the paper has been published with this citation: Yao Zhang, John L. Recker, Robert Ulichney, Giordano B. Beretta, Ingeborg Tastl, I-Jong Lin and John D. Owens, "A parallel error diffusion implementation on a GPU", Proc. SPIE 7872, 78720K (2011); doi:10.1117/12.872616. The link is http://dx.doi.org/10.1117/12.872616. In that paper we focussed on achieving a possibly efficient CUDA implementation of the BIPED algorithm.

A new paper, Yan Zhou, Chun Chen, Qiang Wang, Jiajun Bu and Hua Zhou, "Block-based threshold modulation error diffusion", J. Electron. Imaging 20, 013018 (Mar 25, 2011); doi:10.1117/1.3555132 just appeared in JEI. Their focus is on achieving a possibly high image quality with BIPED. Lacking performance data, I do not know how it performs compared to sequential ED. The link is http://dx.doi.org/10.1117/1.3555132.

IBEX Camera Sees a Ribbon in the Sky

The NASA IBEX (Interstellar Boundary Explorer) mission (the size of a kitchen table) was launched in 2008 to map the heliosphere that surrounds our solar system. It carries a High-Energy Neutral Atom (HENA) camera that images energetic neutral atoms, rather than photons, to create maps of the boundary region between our solar system and the rest of our galaxy.


The surprise result (so far) is that the energy and particles at the galactic boundary are confined to a "ribbon" structure that envelopes the heliosphere. For reference, the Voyager spacecraft are just now passing through the heliopause, at about 100 AUs, after more than 30 years of in-flight operation. Both the heliosphere and heliopause are shown below on a logarithmic scale.


For the first ten billion kilometres of its radius, the solar wind travels at over a million kilometers per hour. As it begins to drop out with the interstellar medium, it slows down before finally ceasing altogether. The point where the solar wind slows down is the termination shock; the point where the interstellar medium and solar wind pressures balance is called the heliopause; the point where the interstellar medium, traveling in the opposite direction, slows down as it collides with the heliosphere is the bow shock. [Source: Wikipedia]

Meta-Palette

Little structured data

Today we are mostly interested in large data sets, like the megaimages we mentioned recently. Moreover, we are happy with flat unstructured data, which we comb and mine as needed. Personally, I prefer navigation and structure, but that is a matter of taste. Anyway, what is the trend for little data?

The Totally Color Channel

Large tiled images

Remember the large tiled multiresolution images from Live Picture's IVUE file format and its son FlashPix? Current architectures allow them to make a comeback. New hardware architectures can reduce processing time for gigapixel and terapixel images.

Read the article in the SPIE Newsroom: Multicore speedup for automated stitching of large images.

Japan Prize Ceremony cancelled

The Board of the Japan Prize Foundation has reached a deliberate conclusion to call off a series of events that were planned to honor the 2011 Japan Prize laureates, given the circumstances in the aftermath of the devastating earthquake and tsunami that hit the northeastern coastal area of the Japanese main island on March 11.

There is no ceremony held but the Foundation is planning to hand the medal and certificate of the Japan Prize to the laureates directly; Dr. Dennis Ritchie and Dr. Ken Thompson in the field of "Information and Communication" and Dr. Tadamitsu Kishimoto and Dr. Toshio Hirano in the field of "Bioscience and Medical Science." The Foundation is also planning to invite them to the next year's ceremony as the Foundation's special guests where they would like to express Japan's celebration to their achievement.

Visions of Africa

When I teach my color course I always stress that the visual system does not work like a camcorder: there is no fixed pixel array, no bitmap, and no homunculus in our head watching the bitmap frames on a biological display. True, in the LGN and cortex we can record (distorted) maps of the visual field, but this does not explain color vision.

In the course I have diagrams illustrating how vision is not hierarchical but a network of bidirectional paths. I also reorder the factors in the tristimulus formulæ so it is evident the color matching functions are measures in the mathematical sense, i.e., probabilities for the catch of a photon of a certain energy. The latter means that for example an M cone cannot know if the photon it just catched is green or some other color.

Photon detection in the retina is a quantum effect and we can only describe probabilities. The fact that the brain cannot know the color of a point in the visual field at a given time is generally known as the principle of univariance and was originally formulated by William Albert Hugh Rushton (1901–1980).

That said, the geometric distribution of the L, M, and S cones in the retina is puzzling. Science Now reports on a recent hypothesis claiming on an African savanna 10 million years ago, our ancestors awoke to the sun rising over dry, rolling grasslands, vast skies, and patterned wildlife. This complex scenery influenced the evolution of our eyes, according to a new study, guiding the arrangement of light-sensitive cone cells. The findings might allow researchers to develop machines with more humanlike vision: efficient, accurate, and attuned to the natural world.

Read more at this link: Visions of Africa Shaped Eye Evolution

Honeysuckle

Honeysuckle is not a color term in Nathan Moroney's color thesaurus, meaning none of the contributors to the online color naming experiment ever mentioned this term. It is a reddish pink, which is a color term in his dictionary. Unfortunately Google's Book Ngram Viewer is not of much help, because it cannot distinguish the color term from the widely distributed climbing shrub with tubular flowers that are typically fragrant and of two colors or shades, opening in the evening for pollination by moths. • Genera Lonicera and Diervilla, family Caprifoliaceae (the honeysuckle family).

Indeed, the graph (click on it for a larger view) shows a much higher frequency for honeysuckle than for rose pink, which is just a color term and would be more frequent than honeysuckle.

The appearance of a Flamingo

Once upon a time, a day came when the management at Xerox PARC decided to hold elaborate Open Lab events to share our knowledge and achievements in pursuit of synergies. In the color project we had just finished building a research lab, and our director instructed us to better have a good demo in the Gray Lab, justifying is construction.