Friday, June 5, 2015

E Ink Tricks the Eye with Color -- and Paper

By Jenny Donelan

The E Ink booth is always a fun place to visit at Display Week, probably because it features so many different products, some “real,” some prototypes. E Ink is a versatile material and designers are still figuring out what they can do with it. This year, the range of products on display included shelf labels, smartphones, blood sugar monitors, and decorative pillars featuring dynamic color displays that were part of the actual booth.

One of E Ink’s big announcements at the show was the addition of yellow to its Spectra product line. Last year, Spectra debuted in black, white, and red. This year, you can get black, white, and yellow as well. The product has various uses, including electronic signage and dynamic shelf labeling. E Ink was demonstrating the latter with an exterior booth wall that featured a life-sized photo of shirts on shelves, as if at a store, with actual Spectra shelf labels next to them. From a distance, the whole eye-catching display looked real, as if there were actual shirts on shelves, What’s really interesting, said E Ink’s Giovanni Mancini, was that more than one attendee asked him what kind of display the shirts were being shown on -- to which he had to answer that it was one of the oldest display materials in the world – paper.

There’s been a lot of talk recently about how the e-Reader market has matured, and it has, but E Ink is still shipping 10 to 12 million panels a year, noted Mancini. No doubt many companies would be happy to be serving a “mature” market in that capacity.

Still, E ink has obviously seen fit to diversify its offerings, with a recent emphasis on the electronic signage market. And in January, it announced Prism, which the company describes as a “dynamic architecture product.” Prism uses electronic ink to decorate surfaces such as walls, artwork, pillars, and so forth, much as LEDs are now being used, but with a softer look and of course, with less power consumption. At the show, two different colors of Prism were used to decorate the sides of pillars in one corner of the booth. The colors changed in intensity: one pillar started out as nearly white, became pink, and then red before fading out to start over again.

Prism is available in a wide range of colors, some of which are shown here.

Silicon Hot Melt Is Alternative to Polyurethane Hot Melt and DS Tape

By Ken Werner

At a Display Week poster session on Thursday, June 4, Ryan Schneider, Glenn Gordon, and colleagues from Dow Corning presented their paper, "Silicon Hot-Melt Adhesive Providing Protection, Waterproofing and Reworkability for Precision Assembly of Electronic Devices" -- a title that leaves little to the imagination.

The material, Dow Corning EA-4600 HM RTV Black, was initially developed as an alternative to double-sided tape (and polyurethane hot melt) in the assembly of cell phones and other electronic devices. In this role, the adhesive can run about 20% of the cost of tape in large-volume applications. Because the material requires dispensing equipment that costs in the vicinity of $100,000, it takes high volumes for the much lower material cost to deliver its maximum savings.

One advantage of the silicon hot melt is that it can be used to make beads of 0.5mm or less in, for example, a peripheral seal on cellphone window glass, where maximum screen visibility is crucial. It is, said Gordon, impossible to cut DS tape that fine.

Although the original conception was to use the hot melt as an adhesive for assembly, if you deposit a peripheral bead on only one surface and allow it to cure, it forms a gasket that can be used to provide water- and dust-proofing to a snap-on cover -- and the cover can be removed and re-snapped indefinitely while still retaining its water-proofing characteristics. This approach was used to waterproof the back cover of a recent, popular smartphone model. Although Schneider and Gordon would not identify the model in question, reliable industry sources tell me it was the Samsung Galaxy S5. Dow Corning is talking to other manufacturers about adopting the technique.

Ryan F. Schneider (R) and  Glenn V. Gordon of Dow Corning seemed pleased at the reception of their poster paper.  (Photo:  Ken Werner)

The View From The Standards Podium

 By Tom Fiske

I had the privilege to chair a session at the Symposium Thursday morning on display standards and transparent displays. This session was run by the Display Measurement topical subcommittee, part of the program committee that puts together the conference. Marja Salmimaa from Nokia Technologies (Finland) was my co-chair.

It’s always satisfying when a session that you assembled back in January at the paper selection meeting really comes together at the conference in June. This one demonstrated one of the best things about the conference -- its international nature. Five countries and three continents were represented.

Michael Becker from Instrument Systems (Germany) gave the first invited paper, a very nice overview of the main emphases of the various major standards organizations concerned with displays. Why do we need standards? They fill the need for clear communication between different groups and countries by supplying precise terminology and the taxonomy that provides structure for the terminology. The CIE concerns itself with the fundamentals of photometry and colorimetry. The IEC provides data sheets and standards for display components and devices. The ISO deals with the ergonomics of human-system interaction. He covered some highlights of recent work by those organizations, including measurements for non-planar (curved) light sources and displays, OLED performance in various ambient lighting environments, transparent displays, and the characterization of speckle in optical systems. He concluded his talk by remarking on the complementary topics emphasized by each organization and how cooperation between them is good for the standards setting enterprise.

Kei Hyodo (pictured above) of Konica Minolta (Japan) is Assistant Secretary for IEC TC 110, the group that covers electronic display devices. In the second invited paper, he discussed the history and structure of the IEC TC 110 and highlighted some of the new topics that the working groups are currently engaged in, including touch, lasers, curved displays, and wearable displays. He emphasized the good working relationship with SID and the ICDM.

Xin-Li Ma from BOE (China) gave a nice talk about optical measurement methods for transparent LCDs. He focused mainly on the effect of the display on objects that are viewed behind the display. He discussed the effect on MTF, level of transparency, and color distortion.

The session finished up with a pair of talks from John Penczek and Paul Boynton from NIST (USA). They covered a general framework for characterizing transparent displays and suggested measurement techniques. These were extensions and applications of techniques found in the Reflection Measurements section of the IDMS. They emphasized that reflectance and transmittance factors can be measured and then used to predict the performance of transparent displays in a variety of lighting environments. In other words, take advantage of linear superposition and don’t try to recreate specific lighting environments in order to characterize display performance in various conditions.

CSOT Brings Curved 110-in, Set to Display Week

 By Steve Sechrist 

Not to be outdone by rival Chinese fab BOE, Shenzhen-based China Star Optoelectronics Technology (CSOT for short) was at Display Week showing off its 110-inch curved 4K TV, claiming it as the “world’s largest" curved LCD TV, with dimensions of 2.4 x 1.4 meters. The set includes a 3840 x 2160 pixel (4K x 2K) pixel display in a 110-inch diagonal curved format that offers a sizeable color gamut with 10 bit color at 60 Hz refresh, and a whopping 50K:1 contrast. CSOT product engineer Yuming Mo told us that at its thinnest point, the curved set reached 20mm in thickness (at the edges), growing to 45 cm with a curve radius of 5500 mm total.     

The company also showed a UHD (3840 x 2160 pixel) 55-inch diagonal TV. The set incorporates QD Vision's Quantum Dot technology and claims a 63% boost to color gamut, achieving an extremely impressive color standard with what the company is calling its Super Color Gamut technology. 

Clearly Chinese fabs are serious in their efforts to step up their technology offerings and many experts believe they have reached image parity with some of the best displays in the industry. We agree, and look forward to the consumer benefits from these awesome displays.

Author Steve Sechrist (third from right) stands with the team from CSOT in front of the company’s 110-in. display.

Thursday, June 4, 2015

Android Wear Offers Timely Advice to Display Makers

By Ken Werner

On Thursday morning at Display Week, The Special Wearables Address in the business track was given by Sidney Chang, Head of Business Development for Android Wear, whose topic was "Android Wear Overview and Google's Wish List." (Chang replaced Fossil CTO Philip Thompson, whose scheduled talk was "Why Wearables with a Display Will Not Succeed with Today's Display Companies." I have been assured that the switch was due to a scheduling conflict and not because Thompson was planning on telling us, quite accurately, that display and computer companies can't be trusted to design watches.)

Chang's approach was not confrontational, but he had interesting things to say, some of them aimed directly at display makers. The first was that display makers should think very hard about "improving" traditional display parameters if they impact battery life. Although outdoor visibility is essential, it should be done in ways other than cranking up the luminance. The display must always be on, but it doesn't always have to be on in the same way.  Chang described two modes. The "interactive mode" has full animation and full refresh rate. "Ambient mode" has reduced color depth, reduced brightness, and reduced refresh rate for showing basic information, like the time, whenever the user looks. (Pixtronix and Sharp, are you listening?)

Chang specifically discouraged display makers from going to 300 ppi for watch displays. The extra pixel density isn't needed for most watch apps, he said, and most watches can't tolerate the hit on battery life. 

Chang showed the results of user studies done by Android Wear. Not surprisingly, users want the thinnest watch they can get. Many women feel that current watches, although arguably appropriate for men's generally larger wrists, are too large for theirs. Average wrist diameters are 17.5cm for men and 15.0cm for women. Average wrist breadths are 5.8cm for men and 5.2cm for women. When a group of users (presumably both male and female) were asked whether they preferred a watch diameter of 1.0, 1.1, 1.2, or 1.3 inches, there was a strong bi-modal preference of 1.0 and 1.2 inches.  Of these, participants over 40 years old preferred the smaller size, while participants under 40 preferred the larger. (Display makers, don't try to sell 1.5-inch displays to watchmakers!)

A general issue is trying to meld the very different approaches of watchmakers and people from the display and mobile systems communities. Chang noted that watchmakers and watch users prefer choice and variety. In 2014 Fossil had 8000 watch SKUs under 15 different brands. Typical sales for each SKU were thousands to tens of thousands. Since Google Wear released its API, the most popule apps have been different watch faces, with one app allowing the user to take a selfie of his or her clothing and then match the color of the watch face to the color of the clothes.

Forging compatibility between the watchmakers' need for variety and the display- and system-makers need for volume will be an ongoing topic of conversation.

Wednesday, June 3, 2015

The ICDM Seeks to Raise The Bar - But Will It Be High Enough?

By Tom Fiske

The International Committee for Display Metrology (ICDM) is one of the strongest groups working on standardizing display metrology procedures and techniques. Its members are some of the best display evaluation and characterization experts in the world.

On Tuesday evening, the ICDM had its main meeting. The meeting started with an update of organization activities and proposals for a potential quality certification program and the institution of a student award for metrology.

Things really got going with a number of presentations and proposals from various members for a variety of methods to address some of the most pressing issues in display metrology. A couple of members talked about various problems with and offered some suggestions to improve current methods for measuring and reporting contrast ratio -- especially as it relates to projectors and High Dynamic Range (HDR) displays. There are a couple of ways that ANSI (checkerboard) contrast gives misleading results for projectors -- especially as it relates to typical cinema content. Current contrast methods don’t adequately address dual resolution HDR displays, either.

We also had a couple of good reports about how to evaluate light field and other types of 3D displays. Light field displays are becoming more prominent lately, so this is a welcome development. We had a proposal to update the flicker measurement method in the current IDMS. The new method will be simpler to calculate and be more general. There was a presentation proposing a display quality metric that combines resolution, contrast, luminance, display size, and color gamut. This was nicely correlated to a set of very thorough subjective assessment results.

One of our guests had a nice rant on the evils of specsmanship. He enjoined the ICDM members to join with other parts of the industry to combat misleading reports of display performance. My own view is that part of the reason the IDMS was adopted was to give the industry a definitive set of display evaluation methods. That’s a great starting point, but the ICDM can only do so much. We can certainly raise the banner of how to measure displays properly, but it’s up to the industry as a whole to embrace “no misleading” behavior. What are the chances of that, I wonder?

The ICDM welcomes participation from those interested in these topics. It is a committee within the SID and publishes the Information Display Measurements Standard (IDMS).

10K from BOE Debuts at Display Week

By Steve Sechrist

BOE showed off an impressive 10K display at Display Week. The 10240 x 4320 pixel display (in 21:9 format) is a “technical development” model that comes in a large 82-inch diagonal display, according to development engineer XinXin Mu of BOE. She told us the panel is a one-off that demonstrates the cutting edge of the high-resolution capabilities of BOE as the company begins looking downstream at the future of both display size and resolution. The panel uses a direct LED backlit scheme that is the major reason this behemoth set consumes a whopping 1100W of power. She also said pixel addressing is done from both top and bottom, and uses a standard ASi backplane.   

Even at close-in distance, individual pixels were beyond human visual acuity (at least this human’s pair of eyes) and close inspection of the amazing video images (provided by an upscaled NHK source) revealed such minute detail like a single bird discernable in a wide city view shot, sitting atop the Brandenburg Gate, or details of the rotating restaurant from a distance shot of the Berlin tower. The images are simply stunning. 

BOE PR rep Aly Langfeifei told us the display is meant to underscore just how far China based fabs, (and BOE in particular) have progressed in their technology development, 
So take the opportunity to treat your eyes to the future of displays with this 10K beauty. We were also told work is going on to modify the technology and prepare it for commercial release in the (not too distant) future.

Xinxin Mu, Lt, Aly Langfeifei

What a Difference Two Years Can Make

By Geoff Walker

Exactly two years ago, at Display Week 2013, Cima NanoTech (Booth 646) launched its new transparent-conductor technology (branded SANTE), a silver-nanoparticle conductive coating that self-assembles into a random mesh-like network when coated onto a substrate. Cima was awarded the Display Week “Best in Show” award in the Small Exhibit Category that year.

At launch, much of the excitement was about the “self-assembling” nature of Cima’s technology. A video showing how the material transformed from an opaque liquid to a mesh-like metal network in only 30 seconds caught many attendees’ interest. From Cima’s 2013 press materials and my conversations with its people at the time, it was clear that Cima believed that the technology would work well in large-format (>30 inch) touch screens. However, Cima didn’t know in what applications. One press release said, “SANTE is a platform technology with applications that span across multiple markets,” while another said “applications range from Ultrabooks and laptops, to all-in-one monitors, industry [sic] displays, personal information displays, and other screens that are larger than 10 inches.” And the company didn’t have a clear idea of how to establish traction with its technology. At that time, its focus seemed to be on comparing this technology with other transparent conductors such as silver nanowires, copper metal-mesh, and carbon nanotubes.Remember that new transparent conductors were a very hot topic in 2013…

Now, two years later, it’s almost as if Cima is a different company. (I didn’t spend any time with it at Display Week 2014.)  Its booth is dominated by a 55-inch touch table with a p-cap touchscreen (borderless, of course, like all p-cap touchscreens) made by Cima using its own material. Cima’s focus is laser-sharp on its advantages in large-format touch (e.g., low sheet resistivity, which yields faster touch response, no moiré issues, etc.), and the advantages that the large-format touch market offers today (e.g., high margins, no dominant competitor, multiple applications, etc.). 

Cima has established a solid partnership with the largest ODM in the world, with an agreed-upon strategy that addresses both low-mix/high-volume sales through OEMs and high-mix/low-volume sales through systems integrators. Cima is currently leasing an entire factory in Korea that produces touch sensors, and it is actually planning to purchase the factory once the new funding round that it’s currently seeking is completed.

The applications that Cima is pursuing with its ODM have also come into much sharper focus during the last two years. Number one is interactive whiteboards (estimated to be a market of about 800K units/year globally). In China, the whiteboards will be focused on education because the Chinese government is providing heavy subsidies to its school systems. In the US, the whiteboards will be focused on the enterprise market (e.g., for video collaboration) because that’s where the money is. Cima’s number two application target is interactive digital signage, especially in Asia, where digital signage is much more prevalent than in North America. As you might guess, the great majority of the sales that Cima is expecting in the next year will be in Asia.

I find Cima’s transition over the last two years to be quite remarkable. It has transformed from a technology-obsessed company focused on its cool new transparent conductor (which is actually pretty far down the food chain*) to what seems like an emerging touchscreen supplier with a strong business plan that addresses significant applications in one of the most fertile markets in touch (large-format).

* Transparent conductor è Film è Touch sensor è Touch module è Integrated on display è Application

Tuesday, June 2, 2015

Intel Shows Its Vision of the Interactive Future

By Tom Fiske

Intel Corporation’s CEO Brian Krzanich gave an interesting and compelling keynote address at SID’s Display Week conference in San Jose this morning. His thesis is that the relentless pace of Moore’s law will lead to richer and more engaging interactivity with our devices. RealSense, a collection of sensors and software provided by Intel, enables 3D scanning and sensing of the environment. He and his colleagues demonstrated face recognition and hand gesture control, face-to-face interaction for online video gamers and remote meetings, and technology for more efficient warehouse management. He also demonstrated 3D scanning to 3D printing, real-time collaborative remote working with virtual 3D objects, a floating “piano” interface, and augmented-reality interactive gaming on top of a real-world space. All of these can be made possible by enhanced and rich sensing of the ambient environment and the user.

Krzanich delivered the message that we are on the cusp of something new, and I do not doubt it. Not even mentioned here are location tracking, body sensors, and a wealth of other sensing technologies. New and compelling applications will certainly be found that take advantage of these and other new capabilities. Technical developments make these things possible. We also reveal more of ourselves to gain convenience or capability. Like any technology enhancement, we have to make our own determination as to when the technology adds sufficient value to induce us to part with our dollars -- and to give up a bit more of our privacy.

The Most Pixel-Dense Display in the World -- for Now

By Ken Werner

At Display Week today, Tianma NLT introduced the display with the world's highest pixel density:  847 pixels per inch (ppi). The 10.4-inch LCD has a resolution of 4320 x 7680 pixels -- four times as many as a UHD-TV set -- a 1000:1 contrast ratio, and a luminance of 400 nits. The display is a technology demonstration for now, but Tianma suggested tablets as a possible application.

Is this really the most pixel-dense display in the world?  "To the best of my knowledge," said Tianma NLT's Omid Milani.    

What We Don’t Know We Need Yet

By Jenny Donelan

The show floor at Display Week opened today, and beforehand the San Jose Convention Center was already crowded with people. By all reports, attendance is very strong this year. It looks like it’s going to be a lively show. One reason is the Silicon Valley location, which is convenient for tech industry folks who might like to stop in for the day or part of the day. Once such person is Brian Krzanich, CEO of Intel, which is located in Santa Clara -- a hop, skip, and a jump away from the convention center.

Krzanich actually did more than stop by – he kicked off the keynote sessions with a description of Intel’s gesture-based platform RealSense and of the brave new world of human/device interaction in general. Krzanich described how the GUI and touch-based interface we know is morphing into one in which devices will eventually be able to see, hear, feel, and even “understand” their human users. Krzanich showed some of those cool Intel Jim Parsons commercials, and also inspired listeners with a description of the immersive computing world that Intel is currently striving to create.

I was able to interview Krzanich after his address, and I asked him how much people really want new interactive paradigms. In other words:  Is it a technology push or pull kind of situation? He replied: “If you ask someone on the street if they want a computer that sees in 3D, they’re probably going to say no.” Show them what they can do with such a computer, however, and the story is different. When developers are able to show gamers, for example, new worlds of play based on object and speech recognition, they may sign on quickly.

Krzanich also mentioned the importance of the display industry (and Display Week) to Intel right now, because most of this future interactivity is going to happen via a display. For their part, display makers should take heed of what Intel and other interactive technology companies are up to, lest they miss catching an important new trend.

Metrology: You Should All Just Leave Now

By Geoff Walker

Dr. Edward F. Kelley (KELTEK, LLC) is one of the world’s top experts on display metrology. He spent 31 years at NIST (National Institute of Standards and Technology), where in 1992 he started the NIST Flat Panel Display Laboratory. Ed was the obvious best candidate to teach the Monday Seminar on Display Metrology.

Yet about two minutes before the Seminar started, he told the audience that they should all just leave now because they would be bored, and because he had too many slides (172 – that’s one slide every 30 seconds!). Only one person in the audience actually left, saying “You convinced me!” as he walked out.  The fact that 99% of the audience stayed is a testament to Ed’s reputation and knowledge.

Ed is somewhat of a character. He identified himself to the audience as a “redneck metrologist” – although it wasn’t clear that everyone in the audience really understood the term “redneck”. Ed uses a cartoon character as a kind of avatar; here are two examples from his website:

Ed told the audience that he created the seminar by selecting slides from the 700-slide deck that he uses to teach a three-day course on Display Metrology. He said that it took several passes to get the selection down to only 172 slides. Given that preamble, it’s clear that this was no ordinary seminar. It was like drinking from a fire hose. From my perspective as a knowledgeable display person (but certainly not a display metrologist), I estimate that I understood about 25% of the material. Even so, it was a treat listening to Ed dispense wisdom gained over 40 years.

One simple example is when he was describing measuring zero-luminance black (slide 71). He said that just because you can’t measure it doesn’t mean that it’s actually zero. You must sit in the dark for at least 30 to 45 minutes with the display set to zero-luminance black while avoiding ALL source of light – including LEDs. If after that time you can’t see any light whatsoever coming from the display, then you truly do have a zero-luminance black, which implies infinite contrast.

Ed forcibly stated that if you have any serious interest in display metrology, then you must obtain the IDMS (Information Display Measurements Standard). It can be downloaded as a free 51 MB PDF from, or purchased as a 563-page printed book for $130.

How Do You Know How Far Away Something Is?

By Geoff Walker

The question of how you know how far away something is may not grab your attention in everyday life, but it’s very important to engineers trying to create perceptually correct 3D displays. Dr. Kurt Akeley from Lytro spent the first third of his Monday Seminar, Stereo 3D, Light Fields, and Perception, on this question.

The answer that’s commonly assumed is “binocular depth cues,” including vergence (rotation of the eyes towards a fixation point), accommodation (adjustment of the focal length of the lens in the eye to match the fixation distance), retinal disparity (the out-of-focus retinal images of objects closer or further away from the fixation point), and binocular parallax (the difference in the images sensed by each eye). 

Everybody automatically uses retinal disparity (also known as stereopsis) as a depth cue without thinking about it.  When you look at an object at some distance away, the relative blurriness of objects closer and further away gives your vision system a “context” that helps it judge where the object is in space. 

Image blur also affects perceived scale.  In the left-hand photo below, the city looks normal.  However, in the right-hand photo, the background and foreground have been blurred. Since we tend to assume that blurred objects are close to us, the city suddenly looks like a miniature model.


While binocular depth cues are important, and depth-sensing can be achieved using binocular parallax even if all other depth cues are eliminated, there are many other depth cues. Some of the others include the following:

·       Retinal Image Size:  Since you know that people are generally between five and six feet tall, your brain compares the sensed size of the people on the hiking trail in the photo below with what you know, producing an automatic estimate of how far away they are.  This is also an example of the fact that most depth cues involve a “prior” – that is, some prior knowledge of something that’s related.

·       Texture Gradient:  Because we tend to assume that a texture gradient is uniform (another prior), a difference in texture such as in the two sets of rocks circled in the photo above also becomes a depth cue.

·       Lighting:  The illumination of an object with light produces shades and shadows; this can make it easier to identify an object, which in turn can make it easier to determine how far away it is. If multiple objects are involved, since we know that an object that casts a shadow on another object is closer to the light source, we can determine which object is closer.

·       Linear Perspective:  Depending on the prior, a scene shown in linear perspective can be identified as something with depth (e.g., a straight and level road going to a point at the horizon) or an abstract grouping of shapes and lines that provide no depth cues. 

·       Aerial perspective:  People who live in mountainous regions are used to judging distance based on the haziness of distant mountains (the haze is caused by small water and dust particles in the air). The further away the distant mountains are, the hazier they look. However, if these people go to a different mountainous region with a different amount of haze, their prior no longer works.

·       Motion Parallax:  We tend to judge an object’s distance based on how quickly it moves. The closer an object is to us, the quicker it appears to move; the further an object is from us, the slower it appears to move. Because objects that are further away stay in our visual fields longer, we perceive the objects that are further away as moving slower. This is a monocular depth cue, that is, it is perceivable through the use of one eye.

·       Monocular Movement Parallax:  Closing one of our eyes and moving our head produces a depth cue because the human visual system can extract depth data from two similar images sensed serially in the same way that it can combine two images from different eyes.

·       Occlusion:  When one object partially blocks the view of another, we instinctively know which object is in front, i.e., which is closer. In one of his demos, Dr. Akeley showed the audience a short 3D video of three rectangular objects rotating around each other in space and asked the audience to identify what they were seeing. In the first viewing, occlusion was turned off in the graphics software so that one object never blocked the view of another.  In this situation it was extremely difficult to determine what we were seeing. When Dr. Akeley turned on occlusion, it was immediately obvious what the objects were. Interestingly, even though we then knew what the objects were, when occlusion was turned off, it once again became very difficult to identify them.  The human visual system expects and uses occlusion as a fundamental depth cue – in fact, occlusion is believed to be the strongest depth cue of all, even stronger than binocular effects. 

A Better TV Than UHD, AMOLED Burn-in, and More -- Short Courses and Seminars at DW

By Tom Fiske

One of my favorite parts of Display Week is the educational component. Every year, SID brings together an impressive group of display industry experts to share their expertise via short courses and seminars.

Sunday is the day for short courses; four-hour sessions that cover the basics of displays and related topics. This year, on Sunday afternoon, I was able to stop in at Jim Larimer’s (ImageMetrics LLC) short course on color science and its relevance to imaging and displays. Jim started out with the famous image of “the dress” that set the internet aflame a couple of months ago and continued with a lively description of the history and origins of color science; including forays into physiology and evolutionary biology. Dr. Larimer held the attention of the room with a very cogent and thorough explanation of color matching and color difference metrics, the role of context in color appearance, and contrast and luminance in real and rendered scenes. I would have appreciated a bit more time on the application of the principles of color science to modern displays, however. For a more detailed look at this course, see reporter Geoff Walker’s blog post, “What Color is This Dress?”

On Monday, we get a comprehensive series of ninety-minute seminars that provide a practical overview of several types of display related technologies. One memorable seminar was “High-Dynamic-Range Imaging and Displays,” given by Scott Daly and Timo Kunkel from Dolby Laboratories, Inc. Dolby’s version of this technology (i.e. “Dolby Vision”), which it has been working on for some years, is scheduled to be available to consumers later this summer. Daly and Kunkel described how the technology delivers about 6+ orders of magnitude of luminance dynamic range - -yielding super-bright highlights and good shadow detail simultaneously. Typical LCDs can only render about 3.5 orders of magnitude of dynamic range. Dolby Vision also accommodates expanded color gamut. I believe that this technology is much more compelling than 4K UHD -- I know what’s going to be on my Christmas list.

Ed Kelley (Keltek Research) is editor-in-chief of the “Information Display Measurements Standard” published by SID and the ICDM. He gave a whirlwind tour of important display metrology issues in his well-attended seminar. Ed is one of my favorite presenters and he did not disappoint. His slides serve as an important reference and remind about important factors to be considered when making display measurements. In Ed’s considered opinion, it’s not worth making a measurement if you’re not going to do it right.

Professor Jun Souk of Hanyang University delivered a seminar on the basic operation and challenges facing AMOLED displays. A variety of performance, lifetime, manufacturing, and cost issues -- especially compared to LCDs -- represents a significant impediment to the continued viability of the technology. He called out backplane performance and cost, patterning, lifetime, and image burn-in as particular concerns. AMOLED continues to chase LCD in cost and resolution

Monday, June 1, 2015

What Color Is This Dress?

By Geoff Walker

Jim Larimer’s Sunday Short Course,The Fundamentals of Color Science and the CIE Color Standards, kicked off with a dress photo that went viral on the Internet in February 2015.  Depending on the observer, the dress appeared to be either blue and black or gold and white. What you can’t tell from the photo is the color temperature of the light in which the photo was taken. It turns out that it was taken at sunset in very reddish light. The point of the photo (and a recurrent theme in Jim’s course) was that color is an experience, not a physical property of material. Everything about color perception is contextual; expectations about the light-source influence the perception of color. For the full story on the dress, see this CNN video and these articles in Wired and in Wikipedia.

In one of dozens of interesting illustrations and illusions, Jim demonstrated that the colors we experience also depend upon the spatial context near the region of interest. He did this by enlarging his consulting company's (Image Metrics) logo. When viewed at small size, the colors of the words “Image” and “Metrics” seem obviously different. Yet when enlarged sufficiently so that the spacial frequency content of the image on the retina is much lower, the colors are actually seen to be identical. The spatial signal evoked by an image depends on both the edges in the scene and the viewing distance.

  Jim’s course was built around three main themes, as follows:

·         Color is an experience, not a physical property of material (as above)

·         The human vision system is an amazingly complex mechanism

·        The 1931 CIE XYZ color system is good for controlling the image created on the retina (i.e., the “quantum catch” signals created in the outer segments of the cone photoreceptors) but it’s not applicable to our perception of color, which depends on the spatial and temporal context of the image and how the quantum catch signals are processed by the human visual system.

It’s impossible to report on even a tiny fraction of the 217 informative slides that Jim presented in his four-hour course. But part of the reward of attending a course that covers the interaction of humans with their environment is the abundance of interesting “factoids” that one picks up along the way. For example:

·      Every organism on Earth that is able to sense light developed that sense based on the spectrum of sunlight, shown in the following illustration from the Sunlight article in Wikipedia.

It would be easy to write another entire page explaining all the information embedded in this illustration; instead, I recommend reading the Wikipedia article. Jim also recommended the book Animal Eyes, which compares all known types of eyes in the animal kingdom.

·      The blood vessels in the human eye cast shadows on the retina, but we don’t see them because they’re not moving.The human vision system is continually calculating derivatives, so if there’s no motion we don’t see anything.

·       No matter how bad our visual acuity is, the world still looks sharp.  This is because the world is a percept (an impression of an object obtained by use of the senses). The signal processing that our brain does in vision is vastly better than any computer that anyone can build yet, but even with as much as we know, it’s still not clear how much processing is happening in the early eye-cells versus in the brain.

·       At the time the CIE color-space was created in 1931, there were no calculators capable of easily handling negative numbers.  The color-matching functions were therefore made all-positive.  This in turn led to the necessity for non-real primaries, i.e., the resulting XYZ values are imaginary primary colors that are outside of the gamut we can actually see and cannot be created with real lights.

·       While industry is struggling to create adequate high-dynamic-range (HDR) cameras, we humans already have it.  We can view a scene that contains both deep shade and sunlight and see detail in both.  The reason is that our retinas can change sensitivity locally, that is, one part of the retina can have a different sensitivity than another part.

·       The tines of a hair comb far enough away will appear to be black and white regardless of what color they actually are.  This is because the maximum spacial frequency that we can see is about five cycles per degree.