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How Viewing Environment Conditions Can Corrupt Or Enhance Your Calibration - Page 4

post #91 of 108
Quote:
Originally Posted by GeorgeAB View Post

You are the first customer to have stated such a problem since we started using the baffle tubes. It would better to use something less flammable than paper. Perhaps a small piece of electrical tape?

Thanks George, I shall try electrical tape.

Is the baffle tube supposed to be tightish by the way?
post #92 of 108
Thread Starter 
Most of them end up not being loosey-goosey, like yours seems to be, due to how close the lamp (bulb) ends up being to the fixture body. I've noticed that an occasional fixture assembly allows a bit more space under the lamp. This kind of discussion is actually getting off topic and would be best conducted via the company's e-mail.
post #93 of 108
George, has any work been done, from either a calibration standpoint, bias lighting, etc., to account for quantifiable differences in viewer eyesight?

I'm really glad that efforts have extended beyond the display device to address other factors in the signal chain that can effect how information is conveyed through the medium of television. While I believe that measured reference output from a display is a good starting point for conveying "all that which the artist intended", I also submit that the statement "only a display calibrated to the reference standards can convey to the viewer the image the artists intend" is nothing more than a conceit...I'll try to explain why I feel this is the case.

It is a well known fact that age can affect a user's eyesight. As we age, we lose the ability to distinguish levels of contrast, and our ability to gather information from the presence of certain colors at a given luminance degrades over time. It is my belief that my own vision adequately approximates an ideal from a color reproduction standpoint, to where I prefer an image calibrated approximately to the reference standard...in other words, I don't have any eyesight trouble that I know of in the waking world beyond that which is easily corrected by prescription lenses. However, this is not the case for many people: For some, a display calibrated to at or below reference black may appear overly dark, and not because of something so conveniently nebulous as user preference...rather, a viewer's ability to perceive information rising out of black may be hindered by that user's eyesight in a way that is outside that user's control or ability to alter perception.

Comments about reference displays accurately depicting the intent of the artist abound, but I hardly believe that any artist, engineer, or other person in the video production chain believes that information immediately visible to some, and representing information important to the artist, be completely lost on a certain subset of viewers. For example, I don't believe that it was James Cameron's, or any other person who worked on the movie Aliens, intent that the viewer perceive half the movie as a group of people screaming and firing weapons in a broom closet with the door closed, with only the occasional explosion or muzzle flash to let the viewer know they didn't forget to switch on their display. This is an absurd notion, yet it is the reality for some viewers of a reference display.

My question, then, becomes one of science, not of perception...in my view, the human eye is simply one more filter in the signal chain...has any work been done to provide standards for addressing differences in human visual acuity, or methods involved for assessing user eyesight in a way that is quantifiable and able to be applied to display calibration, bias lighting, etc? For example, instead of calibrating a display to a reference RGB 16 for black and 235 or above for white, is there any standard or procedure that would narrow this for a user of limited eyesight? Although said differences in vision may not be easily corrected with a simple linear factor, I would suppose that there is a method by which an adequate transform function may be arrived at for certain maladies of the eye, and accounted for on a lookup table or other similar means of tracking, similar to (but perhaps more dimensionally complex than) the way in which a viewer's ability to distinguish letters on an eye chart results in a prescription for eyewear.
post #94 of 108
Thread Starter 
The motion imaging industries rely on what are generally regarded as objective instruments, NIST trace-able for consistent accuracy, when setting up critical monitors in program mastering. Standards, engineering guidelines, and recommended practice documents guide the technicians who calibrate and use these monitors. Image performance and viewing environment conditions follow these methods. All this theory and practice is intended to unify results, independent of unique/individual human variables. Since natural reality observable around us doesn't attempt to compensate for unique perceptual differences in each viewer, each viewer must make adjustments to suit their requirements.

Video viewing environment recommended practice is our reference starting point. Each viewer may have to tweak viewing conditions slightly to suit their unique system challenges (always remember- the viewer is a legitimate component in the system). Just as there is no perfect display, there is no perfect viewer. All displays have adjustment features to compensate for non-linearities in practical use. Our challenge is to understand how to use such adjustments properly in the context of imaging industry standards and practices. The goal should always be to achieve/preserve image fidelity and artistic integrity as much as system components allow.

Understanding all of this, I don't see how a practical/reliable/affordable method would be do-able to address the issues you have presented. You are certainly free to pursue the development of such solutions. Personally, I think your inclusion of prescription eye wear may be the right remedy for the vast majority of people. What has been done for the cases you mention in the commercial cinema? How about computer monitors? Photo printers? If nothing has been done, why not?

Best regards and beautiful pictures,
G. Alan Brown, President
CinemaQuest, Inc.
A Lion AV Consultants Affiliate

"Advancing the art and science of electronic imaging"
post #95 of 108
Quote:
Originally Posted by GeorgeAB View Post

What has been done for the cases you mention in the commercial cinema? How about computer monitors? Photo printers? If nothing has been done, why not?


Why, nothing, of course...they adhere to a reference standard because they must serve the larger audience, whose vision, on balance, probably approximates what the engineer doing the master has/had.

The difference here is that a display used in a personal environment may be set to the needs of a single individual...and indeed, may be the only place said individual has the opportunity to be imparted all the information normally visible to the majority of others watching displays calibrated to a reference standard.

I also understand that a reference display can be said to most accurately mimic reality, if said reality is recorded with a reference camera, etc., and the resultant image is measured with reference equipment. For some, that is enough. But for those experiencing loss of vision over time, television might be the only refuge they have capable of providing an approximation of the sights and sounds they became used to over most of their lives, then were deprived of.

It is analogous to my example of prescription eyewear (but the example doesn't convey all aspects): I need glasses to read. You can speak all day on the advantages of a given printing or other process of production in the conveyance of clear images...but without my glasses in the signal chain, even the Mona Lisa herself is a blurry mess, and what is reported by my eyes could not be described in any fashion as "the intent of the artist". I'm not suggesting everyone view the Mona Lisa through my glasses; I am, however, suggesting that a personal device may be constructed (prescription glasses) by which the image, though altered from the norm, conveys more accurate information from the artist to the viewer, and enables more people to enjoy the work in measurably the same way that the artist attempted. By virtue of the controls on many televisions, I submit that a television could be another such device for some people.


Now, you can argue that manufacturers/artists do not by and large make print or artwork in sizes that take into account nearsighted people, but for a visual reproduction system in my own home, where lack of other alternatives exist, I may be very right in pointing out that there is a definite desire on the part of some consumers for devices that can...indeed, in some instances, there is a need.

I'm not suggesting that manufacturers or calibrators should account for glaucoma or retinal damage in their designs for consumer-grade devices, I was just wondering if any research has been done to, say, match a reference gamma curve to an individual's eyesight in order to provide a more meaningful approximation of the intended information in transit (and indeed, for said individual, more closely resembling that which the engineers saw on their reference display)...in other words, have we gone beyond the simple brightness/contrast adjustments to account for user eyesight in a measurable and predictable way, or is it a question that has not even been posed by display science (although I doubt this is the case)?

In a general sense, I believe that the reference standards exist for a valid and true purpose...if the engineer's vision and preferences can be regarded as "accurate" (which is quite the supposition in and of itself), and the medium of transmission and measurement be agreed upon, then reference points can provide an example of a display's ability to be adjusted and adhere to certain behavior in repeatable fashion. For a viewer whose vision behaves in accordance with the production team's, these reference standards may represent the points where a display best conveys the experience the artist intended. But I think people in this forum get "reference standard" and "best" confused. There is (gasp) a sense of elitism that exists here that doesn't take into account changes in vision over time, and neglects the end user's vision as a valid and often-times predictable and measurable component to information retrieval. I submit that if any user of this forum were given back the eyesight they experienced as a child, it would come as a shock to them with regard to the values they attribute to the color red, for example, and the amount of information they received about the world through those younger eyes. Perhaps what some regard as "wrong" settings, designed to sell televisions in retail settings, or set to the desires of an individual, more closely approximate that past experience of reality for some...and indeed, from an objective standpoint, could serve to be more beneficial in terms of the amount of accurate information transmitted, for more people than would be guessed by the majority of forum members.

We would do well to remember that all these standards, the D65 gamut, standards for brightness and contrast, even the bit rate of various transmissions, are all organized within, or a subset of, a set of perceived boundaries of human senses. I believe that reference standards for display emissions exist as a starting point, and I envision (pun intended) a world where more differing aspects of the user's own senses are quantified and adjusted for, allowing us to come closer to achieving the common experience and enabling a more personal means to communicate accurate information.

For the time being, we have enough of a problem just getting our sets to behave in accordance with agreed upon, uniform standards. One might express a certain level of concern that manufacturers are pursuing 3-D and internet-enabled entertainment in an environment where they don't even have color right yet for the majority of consumers. In 2010! But my hope is that we can arrive at that point one day, and that we move on from there. Who knows? Perhaps reference quality will, for all intents and purposes, be achieved with OLED or some other technology...but my sincere hope is that we do not stop at that point.
post #96 of 108
Thread Starter 
Don't hold your breath. I think it's doubtful such solutions would be economically viable for anything other than an outboard video processor of some sort, if even that. I suggest you devote yourself to starting a new thread to promote your ideas, hopes, and dreams. This is getting way off the topic of this thread.
post #97 of 108
Quote:
Originally Posted by GeorgeAB;18148787I View Post

suggest you devote yourself to starting a new thread to promote your ideas, hopes, and dreams. This is getting way off the topic of this thread.

Agreed, it's a little OT for this thread, but thanks for your time in answering.

Well, it's not that far OT:

Quote:
Originally Posted by GeorgeAB View Post

The world's most perfect calibration instrument cannot measure how our brain interprets what our eyes see. Some attempts have been made to emulate how humans perceive light but science has yet to produce an instrument which tells the whole story.



Quote:
Originally Posted by GeorgeAB View Post

Don't hold your breath. I think it's doubtful such solutions would be economically viable for anything other than an outboard video processor of some sort, if even that.

I dunno...ten years ago, if you'd have told me there'd be an afforable device that could fit in your ear discretely, offering a frequency response filter designed around your own hearing to return it to what you enjoyed years ago, and that said device would wirelessly connect to your telephone, stereo, or television system, I'd have thought you were talking Star Trek.
post #98 of 108
Thread Starter 
Quote:


Well, it's not that far OT:

Nice try. This thread is about viewing environment conditions. Your points became focused primarily on display adjustments that could compensate for individual vision problems. That's why I suggested you start your own thread. Such a discussion may have interest and merit within this community, but the only sure way to tell is to start one in its own thread. For clarity, simplicity, and coherency, I would like this one to stay on viewing environment principles.
post #99 of 108
I have a 50G10 Panny plasma in a "theater room" with no windows and no ambient light (other than my receiver display). I'm always looking for ways to improve the perceived contrast ratio of my display and I was thinking about bias lighting as a way to improve this. However, I'm not sure that I can use bias lighting and here's why...

My display is on a stand in a wall alcove. In essence, the display is flush with the walls on either side of it but since it is in an alcove, there is about 2' of unused space behind the display. If that wasn't enough, the alcove has 2 built in shelves. One is directly behind the center of the display and the other one is directly above the top of the display. I'm assuming that if I install a bias light on the back of my set, it will do no good because the light will not reflect properly and I most definitely will not get an even amount of illumination around my set.

Can someone please chime in on this. Is it worth it to try the lighting? I do not get any eyestrain while watching the display for hours so I would be installing the lighting strictly for improved contrast ratio perception since Panasonic decided to elevate the MLL's of their displays after certain 'on' hours. If the back of my set faced a flush wall I probably would have already purchased the lighting but I don't want to get stuck with a $60 light that might not do what it was intended to do because of my wall situation.
post #100 of 108
Thread Starter 
Your assumptions are correct. Unfortunately, many display systems were originally designed without a sufficient understanding of video best practices. Many times compromises are unavoidable, so we do the best we can with the hand dealt to us. You could consider walling off the alcove, either permanently or temporarily (like with movable acoustic panels). It sounds like this is a room you have dedicated to watching movies. You get to decide what your personal lifestyle priorities are.
post #101 of 108
I have a 6500K bias light on beige colored wall. When I measure the reflected bias light with a meter, I get somewhat warmer color than the desired D65. I don't recall the exact number but I think it was between 5000K and 6000K. I guess this is expected due to the wall color. Is there a way to remove this color bias? Try using a bulb with higher temperature rating (e.g. 7000K) or add a blue filter? I suspect many people have the same issue but I couldn't find any previous discussion on this topic. TIA.
post #102 of 108
Thread Starter 
You could try using pale blue theatrical filter gells but they will only take the yellow out. There will be red content in the wall color as well, and who knows what other colors.
post #103 of 108
Thread Starter 
I was informed by one of my customers that he learned about bias lighting from this 30 minute video program: http://revision3.com/hdnation/koreatrip . The portion discussing bias lighting is from 18:53 through 23:10. It doesn't mention my company or products but is the best presentation video I've seen on the topic to date. You don't have to watch the entire video stream. Placing your mouse cursor in the video image, once the video fully loads, reveals a slider you can use to select the right time into the program.
post #104 of 108
Thread Starter 
Here's a direct link to just the bias lighting section of the video:
http://revision3.com/hdnation/koreat...bias-lighting-
post #105 of 108
Thread Starter 
These videos demonstrate how even subtle changes in ambient lightness can instantly alter our black level perception of an object: http://www.youtube.com/watch?v=xl1lL...eature=channel ; http://www.youtube.com/watch?v=rFmgSP97fTg ; http://www.youtube.com/watch?v=kdOQBPCOk5w&NR=1 http://www.youtube.com/watch?v=MMJ6t...eature=channel . This explains why backing up a TV with a dark wall can be counterproductive in preserving convincing blacks on the screen. Only the darker portions of the screen image are enhanced by a lighter surround. The lighter areas of the image are not affected, therefore increasing perceived contrast ratio as well. These quotes document this characteristic:

"Contrast could be considered to be the most significant quality that impacts not only the perceived depth of an image, but also affects the apparent sharpness.....While the luminance level of a given image affects how the eye perceives contrast and detail, the ambient conditions surrounding the image can also have a dramatic impact. This phenomena was studied by Bartleson and Breneman (1967) to examine the impact of perceived contrast based not only on the luminance level of the image but taking into account the surrounding ambient luminance levels as well. Their results showed that the perceived contrast increased as ambient luminance increased. With the increase in ambient luminance, the eye interprets black levels as being darker while the impact to the white level is minimal. Since the perceived difference in dark areas is greater under the higher ambient luminance conditions, the perceived contrast is higher. It is a natural tendency to want low ambient luminance levels to strive for "better" perceived image quality and what is thought to result in higher contrast. However, in reality, the opposite is true. This tendency may be justified for current direct view CRT televisions due to the issue of glare that results from the glossy surface of the glass tube [also true for certain flat panel displays today]. With less ambient luminance, the glare is reduced- but it may be important to keep some ambient luminance behind the television [as in the case of bias lighting] to keep the perceived contrast higher.....While sharpness can affect the apparent contrast of an image, the converse is true in that contrast can also impact the apparent sharpness of an image. Images that have lower contrast will appear to be not as sharp as an image of the same content, but with higher contrast.....A subjective study was then conducted to verify the impact that ambient lighting has on perceived contrast. Several non-technical (and thus presumably non-biased) and technical observers were asked to compare a series of images with various ALL [average luminance levels] under different ambient luminance extremes in order to understand the impact that ambient viewing conditions might have on the perceived contrast between the two television technologies [CRT and DMD (DLP RPTV)]. Under dark ambient conditions, the result for images with an ALL > 5% was found to be equal between the CRT and the first DMD display. However, under bright ambient conditions (about 250 nits of luminance on the wall behind all of the units), the DMD display was favored over the CRT by 50% of the observers as having higher perceived contrast.....This proved that ambient conditions have the effect of potentially raising the black level threshold of the eye above the actual black level of the television such that the perceived contrast ratio is higher." from the SMPTE Journal, 11/02. 'The Importance of Contrast and its Effect on Image Quality' by Segler, Pettitt and Kessel

"Their experimental results, obtained through matching and scaling experiments, showed that the perceived contrast of images increased when the image surround was changed from dark to dim to light. This effect occurs because the dark surround of an image causes dark areas to appear lighter while having little effect on light areas (white areas still appear white despite changes in surround). Thus since there is more of a perceived change in the dark areas of an image than in the light areas, there is a resultant change in perceived contrast.....Often, when working at a computer workstation, users turn off the room lights in order to make the CRT display appear of higher contrast. This produces a darker surround that should perceptually lower the contrast of the display. The predictions of Bartleson and Breneman are counter to everyday experience in this situation. The reason for this is that the room lights are usually introducing a significant amount of reflection off the face of the monitor and thus reducing the physical contrast of the displayed images. If the surround of the display can be illuminated without introducing reflection off the face of the display (e.g., by placing a light source behind the monitor that illuminates the surrounding area), the perceived contrast of the display will actually be higher than when it is viewed in a completely darkened room." from 'Color Appearance Models,' by Mark D. Fairchild, Ph.D., of the Chester F. Carlson Center for Imaging Science: Munsell Color Science Laboratory

Best regards and beautiful pictures,
G. Alan Brown, President
CinemaQuest, Inc.
A Lion AV Consultants Affiliate

"Advancing the art and science of electronic imaging"
post #106 of 108
Thread Starter 
Here are a couple of pertinent excerpts from Charles Poynton's 5/26/10 article titled: 'B, V and M Are Obsolete'

"I use the word “reference” because the display used at the end of the
content creation chain establishes the intended reference for all downstream
displays. If an identical display is present downstream in an
identical environment
, then it should present an identical picture. In
the consumers’ premises, we don’t expect the tight tolerances of
a studio display, but we do seek the same aim points."

"Color appearance is strongly influenced by surround conditions. My
recent proposal for a new standard is entitled 'studio HD reference
display and viewing conditions.'"
[emphasis is mine]
post #107 of 108
Hi,

I have a question regarding how much of the space surrounding the tv should be of neutral color. Should I aim to make everything in my field of view neutral, all the way to the very limits of my peripheral vision? Or would 12 or so inches around the screen, like Ictusbrucks is planning, be sufficient?

Thanks in advance, lots of interesting info in this thread.
post #108 of 108
Thread Starter 
Quote:
Originally Posted by AudioVideoPhilia View Post

Hi,

I have a question regarding how much of the space surrounding the tv should be of neutral color. Should I aim to make everything in my field of view neutral, all the way to the very limits of my peripheral vision? Or would 12 or so inches around the screen, like Ictusbrucks is planning, be sufficient?

Thanks in advance, lots of interesting info in this thread.

As in life, most things in this topic are by degrees. I have encountered no definitive/authoritative statements regarding your question. It's a human condition to gravitate toward dogmatism and rigid pronouncements. The ideal is good to shoot for, just not always 100% practical in specific applications. Most important is to understand the essential principles involved and intelligently adapt to conditions in the specific system.

In other words, provide as much neutral surround as feasible. Any amount is better than nothing. Balance the priorities at issue for your circumstance. Far too many system designers don't know enough about viewing environment principles and human perceptual factors to make informed and balanced recommendations.
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