Ambient contrast ratio of LCDs and OLED displays - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 12 Old 03-25-2019, 12:16 PM - Thread Starter
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Ambient contrast ratio of LCDs and OLED displays

I found this research article interesting, measuring contrast ratios of OLED/LCD displays relative to the ambient lighting.
PDF: https://www.osapublishing.org/oe/vie...26-33643&seq=0
HTML: https://www.osapublishing.org/oe/vie...eq=0&html=true



I mean it's not that unexpected that the contrast ratio is higher with low light, for example this is for TV sized panels:

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post #2 of 12 Old 03-25-2019, 12:52 PM
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Your link does not work.

To provide context, this article gives the levels of illumination suggested for a variety of environments: https://www.noao.edu/education/QLTki...oor+indoor.pdf

In short, the 300 lux is not an overly high value for indoors.
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post #3 of 12 Old 03-25-2019, 01:03 PM - Thread Starter
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Quote:
Originally Posted by bobknavs View Post
Your link does not work.

To provide context, this article gives the levels of illumination suggested for a variety of environments: https://www.noao.edu/education/QLTki...oor+indoor.pdf

In short, the 300 lux is not an overly high value for indoors.

Thanks, I fixed the link now. And you're right 300 lux is not a lot, but as you can see even such a brightness has an enormous effect on contrast ratio.
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post #4 of 12 Old 03-25-2019, 02:03 PM
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While the theory sounds sound, the practice doesn't bear it out.
You may want to look at cell phone measurements. The only displays able to hold a CR over 4.0 in daylight are OLED. About 3.5 is where LCD top out and OLED top out at about 5.5.

So, the graphs above are theoretical and do not match the measurements.

They were modeled on very simple theoretical equations, while real life is much more complex. Even LCD designed specifically for light rejection still reflect and diffuse a lot more light than emissive screens. Also, the absolute values of contrast in real life are much lower than shown on the graph.

I've experienced this in practice; it's mostly just possible to see something on an OLED phone out in the sun and mostly almost possible on the brightest LCD ones.
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post #5 of 12 Old 03-25-2019, 02:10 PM
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Originally Posted by AnalogHD View Post
You may want to look at cell phone measurements. The only displays able to hold a CR over 4.0 in daylight are OLED. About 3.5 is where LCD top out and OLED top out at about 5.5.

Thus, the graphs above are fake.
They were modeled on very simple theoretical equations, while real life is much more complex.

I've experienced this in practice; it's much more possible to see something on an OLED phone out in the sun than any LCD one.
The only real measurements in the paper are of cell phone displays. (DisplayMate Technologies Corp, http://www.displaymate.com/) I don't think that the measurement conditions resemble a phone "out in the sun"; the light source is supposed to be very diffuse, as if the phone was illuminated from all angles.

I'm not sure that this has much interest to home theater. The conventional wisdom has always been that if you wish to enjoy the infinite contrast ratio of an OLED, the room has to be pretty dark.

The viewing angle considerations might drive buyers to OLEDs even for a room that isn't really dark. (I think I've read that some new Samsung LCDs are much improved in that, but they may not be cheaper than OLEDs.)

I think that a reasonable reaction to this is "meh".
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post #6 of 12 Old 03-26-2019, 10:00 PM
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ABL makes the simulation more tricky. An OLED TV can only do 160 nits for 100% window.

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post #7 of 12 Old 03-28-2019, 08:04 AM
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In my living room, in ANY light condition, my OLED's better blacks are readily apparent compared to the outgoing Panasonic ST60 (measured at 0.002 ftl and after it was calibrated ANSI contrast of something like 15,000:1). Without doubt the darker the room the more the blacks standout, but the point is even with normal ambient lighting the better contrast of OLED is easily realized.

My reasonable guess is that a high end LCD's would fare about the same as the ST60, despite the extra brightness on tap. The best LCD's are getting something like 6,000:1 native contrast and boosted to around 15,000:1 with FALD, going on memory I think the best blacks they see is around 0.006 ftl, which isnt bad, but significantly higher than the ST60 that I compared with. The overall contrast ratio should be similar enough between a high end LCD and the ST60, so that is what I am making my assumption on. While LCD might get brighter than OLED's, the limited contrast ratio will be the limiting factor, and this is also noted by the phone screen examples above.

As a bad comparison to the LCD that I have, it does a bit over 300 nits full screen (almost double the OLED), is limited to about 1,400:1 contrast, and has a matte finish on the screen rather than a proper black filter. No matter the settings or light conditions it looks like a washed out mess. It is a far cry from a high end LCD, but an easy example of why contrast is more important than overall nits.
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post #8 of 12 Old 03-29-2019, 11:25 PM
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Sony Z9D is achieving 0.005 fTL according to measurements taken by HDGuru. I think the 940e goes a tad darker, but it seems even these flagships fall short.
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post #9 of 12 Old 03-30-2019, 08:21 PM
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Quote:
Originally Posted by video_analysis View Post
Sony Z9D is achieving 0.005 fTL according to measurements taken by HDGuru. I think the 940e goes a tad darker, but it seems even these flagships fall short.
Off topic for a moment. Wondering if you got the Z9 yet and how you like it. If so, how is the 3D on it?

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post #10 of 12 Old 03-30-2019, 09:44 PM
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Quote:
Originally Posted by video_analysis View Post
Sony Z9D is achieving 0.005 fTL according to measurements taken by HDGuru. I think the 940e goes a tad darker, but it seems even these flagships fall short.
I love photometric units.

A foot Lambert is 3.426 nits (cd/m^2).

I don't get it. If "black" is 0.017 nits, and the peak luminance is 1600 nits, that would give a contrast ratio of nearly 100k. The measured contrast ratio of a Z9F at rtings.com isn't anywhere near that.
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post #11 of 12 Old 03-31-2019, 09:26 AM
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Quote:
Originally Posted by bobknavs View Post
Quote:
Originally Posted by video_analysis View Post
Sony Z9D is achieving 0.005 fTL according to measurements taken by HDGuru. I think the 940e goes a tad darker, but it seems even these flagships fall short.
I love photometric units.

A foot Lambert is 3.426 nits (cd/m^2).

I don't get it. If "black" is 0.017 nits, and the peak luminance is 1600 nits, that would give a contrast ratio of nearly 100k. The measured contrast ratio of a Z9F at rtings.com isn't anywhere near that.
Contrast on a local dimming LCD isn't as simple as dividing the back by the white. While those may be accurate peak white and darkest blacks for the Z9D, the set cannot do those at the same time in a dimming zone.
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post #12 of 12 Old 03-31-2019, 09:32 AM
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Quote:
Originally Posted by plasma_fan View Post
Contrast on a local dimming LCD isn't as simple as dividing the back by the white. While those may be accurate peak white and darkest blacks for the Z9D, the set cannot do those at the same time in a dimming zone.
Yes, but...

rtings gives a contrast with and without dimming. I presume that the "with" measurement isn't within the same dimming zone. Z9D review: https://www.rtings.com/tv/reviews/sony/z9d

(Significantly better contrast than the Z9F, but nowhere near 100k:1.)
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