Originally Posted by KD8118
I’m no expert on this and there are two opinions on this. Some feel we are not there yet but I feel like how can we not have the processing power to manage double or even quadruple the amount of zones.
This would mean that in order for them to add more zones next year we would have to wait for new hardware to develop. I would be shocked if we are waiting for more powerful hardware to increase the zone count.
I do admit that I may be completely wrong. Maybe dimming algorithms just take an extraordinary amount of cpu power. If someone has a deep understanding of this feel free to correct me.
It is just a form processing where dedicated hardware has not been massed produced. Essentially you have to look at all the pixels in the zone and figure out the average and peak bright pixels in each zone. A good one also knows how much light bleed over there would be from adjacent zones to put in the calculations. It probably would take a couple of passes get the basic part done - first pass based on peak brightness in each zone, second making adjustments for adjacent zone bleed, and then third and forth pass to better blend it. The third and forth passes should adjust how much the LCD opens to blend in better based on the back light (both the directly behind zone and adjacent zone bleed) to prevent banding. In other words if the zone is lets say at 50% light, the LCD has to open the pixels that are supposed to be 50% to 100% and those at 25% to 50%, etc. And if there is too much back light because of adjacent zone additional lighting have to close pixels some even if they are supposed to be 100%.
The review by Vincent shows that the algorithm is not blending in his expanding circle at about 10 minutes in. It is not just the edges of the circle that show the zones, but there is a second ring (and some of the third ring) of zones that show. A zone that is completely inside the circle and non adjacent to the black should be blended in smooth. The ones that have black in them at the edge of the circle have to make the choice of brightness or trying to reduce halos. I attached some screenshots of the TCL 8, Q90R and LG C9 reviews. The Q90R has half the number of zones, but notice how the circle smoothly darkens to the edge as the outer zones dim to keep blooming in the black down. This was the results of more processing passes (the OLED of course does not have to worry about this just ABL).
The Sony Z9G is said to have 720 zones (in reviews), not too far from this set. But, some reviews have mentioned that there are more than 720 LEDs in the back light and Sony is grouping them together in zones rather than controlling them individually. This to me seems to indicate that even Sony in a $13k set does not have the processing power (they are doing 8k) to do a lot more zones. The prior set with BMD from Sony had an estimated 630 zones (in reviews). So, Sony has had a few years and has not bumped up the zone count much. Unfortunately I was unable to find the circle test on the A9G, but I suspect it is as good at blending as the Q90R or it would have been called out in reviews.
So, it is a lot of processing to get it done right. You have to figure out how much each zone is lit, then you have to process every pixel again in the main LCD image to compensate for the back lighting condition.