Home Theater Geeks 439 Transcript

Please be advised this transcript is AI-generated and may not be word for word. Time codes refer to the approximate times in the ad-supported version of the show.

00:00 - Scott Wilkinson (Host)
In this episode of Home Theater Geeks, I answer a question from Dan who's wondering about TV brightness and color as they relate to LED TVs and OLED TVs. So stick around Podcasts you love From people you trust. This is Twit. Hey, there, scott Wilkinson. Here, the home theater geek. In this episode I answer a question from Dan, who writes Regarding the new Sony TVs you covered in episode 432,.

00:48
What I find confusing is this On LED TVs, the colors don't look as deep as on OLEDs, and on LEDs, if I turn up the brightness, the colors look worse to me. I don't mean only blacks, all colors look better on an OLED to me. I don't know if that's called saturation. How would making the Bravia 9 super bright make it look better? I have a 55 inch Sony X90L. I didn't get an OLED because I was afraid it wouldn't be bright enough. After getting this TV, I realized I can fit a 65-incher in my room. I'm considering getting a 65-inch Bravius 7 or 8, depending on how they look, and if the 8 is bright enough, I just don't understand how the brightness can help LED TVs. Well, dan, these are interesting observations and I'm going to help you understand what's going on here.

01:50
Let's review the two technologies. We're talking about LED TVs, which are actually LCD TVs with LED backlights, use LEDs to shine light through an LCD shutter matrix, then RGB color filters, one on each subpixel, a red, a green or a blue. Led TVs have backlights that emit blue light that then passes through a film infused with quantum dots that are green and red, so this is called quantum dot enhancement film. Here we first see a picture, a depiction of what I was talking about before white LED passing through a diffuser sheet, the LCD matrix, the color filters and finally the image. As we move along in this video little clip we see a QDEF quantum dot enhancement film impregnated with red and green quantum dots and the backlight is blue, and so the blue light shines through the QDEF film. Some of the quantum dots get hit with blue photons and then they re-emit red or green depending on their size. While some of the blue light passes straight through, it doesn't hit any quantum dots. So we get red, green and blue which, when combined, make white. That passes through the LCD panel that forms the picture and then passes through color filters on each subpixel to form a color picture. So that's how LED TVs work, and there are two types one that uses quantum dots and one that doesn't, and therein lies an important part of your observation. An important part of your observation.

04:09
So let's take a look at OLED TVs. Conventional OLED TVs combine blue and yellow OLED material behind each subpixel, and blue plus yellow equals white. So the white light is passed from this material under each subpixel, behind each subpixel. It gets electrically stimulated directly and it emits light, and the more stimulation, the brighter the light it emits. That light then passes through a red, green or blue color filter and in the case of conventional OLEDs, as you can see on the left of this diagram, there's also a fourth subpixel which is called white. It's basically clear. It doesn't filter the light, it just lets the white light from the back of the subpixel pass straight through. So these sometimes are called WOLEDs or WRGB because they're red, green, blue and white. Now the Quantum Dot OLED, which is new as of a couple years ago, use a blue OLED material behind each subpixel and the red and green color filters are replaced with red and green quantum dot material, just like the enhancement film. But unlike the enhancement film, the quantum dots are packed so tightly that none of the blue light passes through the red or green subpixel material. All of the blue light gets converted to red in the red subpixel or green in the green subpixel, and the blue subpixel is clear and it lets the blue light through. So quantum dot OLED, qd OLED, does not have a white subpixel. So that's how those two technologies work and we're going to talk about them again in a little bit.

06:31
Most of the time, when you see the range of colors that a TV can reproduce, it's shown or depicted as a color gamut, which is a triangle inside of this sort of horseshoe shape. The horseshoe shape is the range of colors that humans can perceive, but with their eyes, and the triangles are different subsets of that which the TV or the display can reproduce. So you can see, the yellow triangle is the HDTV color gamut, the middle triangle is what's called P3 or DCI, which is what most ultra HD or 4K content uses, and the widest triangle, the biggest triangle, is Rec 2020, actually technically called BT 2020, which is the official gamut of high dynamic range. Now here's the problem with this depiction it only shows you the range of colors at one luminance level, so it doesn't tell you anything about what happens when the brightness goes up or down. For that you need to look at what's called the color volume, which is a three-dimensional shape, and here we can see the color gamut is only at one brightness level, one luminance level, indicated by this dotted line. But as the brightness goes up, you can see that at high brightness, high luminance, the colors sort of converge on white and as you go down to black they converge on black. So the saturation, the depth of the color, if you will, changes as the picture becomes brighter or darker.

08:29
So, comparing QLED and conventional OLED, that is, w OLED the color volume of QLED is actually larger than conventional OLED and we can see this in the next two graphics. Here we see the color volume of QLED, on the left, along with a picture that is a representative of that type of technology QLED and on the right, w OLED conventional OLED and, as you can see, that picture looks somewhat duller and the color volume is not as big, it's smaller. So here's another example of that. This is actually a photograph I took at the Samsung booth that I believe it was the 2017 CES, where they had this. They first introduced QLED, quantum dot, led, backlit TVs and the color volume on the left is QLED and the one on the right is OLED, conventional OLED, and you can see that the OLED color volume is smaller than the QLED. What was really interesting about this demo is that the lower color volumes the one you see towards the bottom of the picture were actual 3D printed objects that you could pick up with your hand and turn around and look at different angles. That was a really excellent way to depict color volume, because otherwise it's a 3D object and to look at it in 2D makes it a little difficult to understand.

10:19
Generally speaking, the reason that QLED has a greater color volume than conventional OLED is that white subpixel in conventional OLED. They put it in there in order to make OLED brighter. Oled inherently is less bright than LCD TV or LED backlit LCD TV, so they put a white subpixel in there to increase the brightness, but it also reduces the saturation as you get brighter. So that's why those color volumes in the OLED case are smaller. They converge to white sooner as you get brighter, converge to white sooner as you get brighter, while the LED backlit LCD TVs don't have that white subpixel and they can retain saturation at a higher luminance than the OLED can.

11:20
Now let's take a look at LED TVs that don't use quantum dots. Okay, so those that don't use quantum dots have a slightly different story. Lg has a graphic that shows color gamut, in this case of an OLED on the left and a conventional LCD on the right, and, as you can see, the OLED has a greater gamut, a wider, bigger triangle, than the LCD does. And the example picture you can see the OLED colors are more saturated than the LCD colors are more saturated than the LCD. Now, this doesn't show you color volume, but it was an example that I thought would be good to see there, which leads me to the fact that you have an X90L Sony X90L 2023 model LED backlit TV which, as far as I can tell, as far as I've been able to determine, does not use quantum dots. Their X95 does and their X93 does, but, as far as I've been able to determine, the X90 does not. Therefore, it does not have as great saturation as you get brighter, and this might well explain what you're seeing. The new Bravia 9 and Bravia 7 TVs both use quantum dots, so they're going to have a greater saturation as they get brighter, larger color volume, and they're going to have a larger color volume than the Bravia 8 OLED, which is a conventional color W-R-G-B OLED with a white sub-pixel. It's not a QD OLED.

13:14
Now, I reject the notion that OLED is not bright enough. It's plenty bright for all, but the very brightest of rooms. So if you're used to watching TV during the day and you got the windows open and it's really bright outside, then yeah, maybe an LCD, an LED, particularly a quantum dot LED, would be better. But in most situations I think OLED is fine. Oled is fine Now. Granted, a W-OLED or WRGB OLED will desaturate its colors as it gets bright You're right about that but so will a conventional LCD LED TV without quantum dots. And granted, oled is more expensive for a given screen size than LEDs. Generally speaking, not that much. For example, the 55-inch Bravia 8, which is the W OLED, is only $100 more than the 55-inch Bravia 7. Now, at 65-inch, the difference gets a little bigger. The Bravia 8 is $500 more than the Bravia 7. So you need to look at your budget for that.

14:43
I still prefer OLED for its deeper blacks, deeper and more uniform blacks and superior off-axis performance. So you're looking straight on both types of TVs look great. As you move off-axis, the LCD TV, led TV will start to not look so good, but the OLED will, and the Bravia 7 does use quantum dots, so that's going to give it a greater color volume, more saturation as it gets brighter, probably more than the Bravia 8, which is a white-based OLED TV, because the Bravia 7 uses quantum dots. Now, ari, regarding your comment about turning up the brightness, making LED colors worse, that has something to do with the fact that the brightness control affects both the top and bottom of the dynamic range. So as you turn it up, the black goes up and the white goes up. They both go up, so you're seeing less good blacks, they're becoming gray and the whites may very well be clipping, so you're going to get lower saturation generally speaking. So it's really no wonder that it makes the colors look worse. It's really important to set the brightness control and the contrast control, which controls only the bright, the high end of the brightness range, not the bottom end. You want to set those correctly to get the best performance out of your TV. So, bottom line, I'd say either the Bravia 7 or 8 would do you well. If you can spend the extra 500 bucks, I personally would get the Bravia 8 OLED, unless you have a room that is just really, really bright, in which case, the Bravia 7 might do you better, but the Bravia 7 is not going to look washed out like your X90 does at high brightness levels. So there you go. That's the answer. That's my answer to your question. I hope it helped. Now, if you have a question for me, please send it along to HTG at twittv. We love to answer as many of those as we can on this show and, as always, we thank you for your support of the Twit Network with your membership in Club Twit. With that membership you can see the video of this show and all of the Twit shows and you can come into the Discord channel and watch us make the show live. So until then, geek out. I did see a comment asking about your thoughts on the Bravia 9, but oh, reststreambot, what is your opinion of the new Bravia 9? Well, I haven't seen it myself yet. I hope too soon.

18:27
Its claim to fame is a peak brightness of 4,000 nits, and the biggest importance of that is that movies on UHD Blu-ray are mastered to a peak brightness, typically of 1,000 or 2,000 nits, but sometimes 4,000 nits.

18:49
One example of that is the Meg, which I happen to be on the soundtrack of, interestingly enough, but that's another story. So a movie like the Meg is mastered to a peak brightness of 4,000 nits. If you have a TV that can do 4,000 nits then you don't need to do any tone mapping. So a TV that can't do 4,000 nits, if you play the Meg on it, as the brightness gets higher, the luminance gets higher, you need at some point to roll it off because the TV can't go to 4,000 nits. So something above whatever the TV's maximum is is going to have to get rolled off. If your TV does do it like going to have to get rolled off, if your TV does do it, like the Bravia 9 and not very many others, you can go all the way to the peak of a movie like the Meg and not have to roll it off. So that's the big advantage there.