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Owen

"True 4K" Discussion

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Sorry mate, but must I always have to point out the obvious ?

The test pattern image you posted above does NOT show 4K. The left side block shows a 2K horizontal pattern NOT 4K, and the right side pattern is 2K vertical resolution.

To be fully resolved the alternating lines must be full black and full white which equals 100% MTF (or no loss). White lines that are grey and black lines that are grey represent a loss of MTF and "resolution". The closer the lines get to 50% grey the greater the loss of MTF and usable resolution.

 

Here is the full test pattern.

Overscan-4K-BenQ-W2700-1024x565.jpg.c3e0af4e1226957853576b03d51cfa45.jpg

 

 

Note that there are blocks of vertical lines to the left of centre and 4 blocks of horizontal lines to the right, not 3 as in the close up image you posted above.

Only the blocks on the far left and far right are 4K. The blocks 3 out from centre are 2K, the blocks 2 out from centre are 1K,  and the blocks either side of centre are 0.5K.

 

So the close up of the test pattern you posted above only goes out to 2K and as we can see even 2K is very poorly resolved with VERY low MTF.

 

 

The colour test pattern that was posted earlier is a mess, no 4K resolution there.

Its interesting a colour pattern was used in place of standard black and white pattern. I'm confident this was done because the black and white line pattern looks a lot worse. 

 

Edited by Owen

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The French review of the Benq W2700 reveal its significant performance short comings.

 

Lumen output after colour calibration = 981 lumens on high lamp and 725 on low lamp, a LONG way from the advertised 2000 lumens. Thats a worse than normal light loss after calibration for DLP projectors.

If wide gamut colour is used output drops to 609 lumens in high lamp mode, bloody useless.

 

Native contrast ratio comes in at a staggering 991:1 native (in scene contrast). Yes thats LESS THAN 1000:1 people, and thats worse than most cheap 1080 DLP projectors. Dynamic  contrast (scene to scene contrast) came in at 2769:1, which is around one tenth the native contrast of a 7 year old base model JVC with no "dynamic" enhancement.

Note that Benq quote a contrast ration of 30,000:1 for this projector, they are only off by a factor of 10

 

BS marketing obviously works and sucks in the uneducated who make perchance decisions based on spec sheet numbers that are down right deceptive and therefore meaningless.

Edited by Owen

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On 04/08/2019 at 1:07 AM, MLXXX said:

Edit:

I've now found such a review for the BenQ W2700. It's at https://7review.com/benq-w2700-review/ :-

 

"Anyway, while imperfect, the line separation was the best I’ve yet seen from this breed of XPR DLP projectors.

BenQ-W2700-Review-4.jpg

▲ Close-up detail of the UHD test pattern delivered as video and captured photographically. The individual lines of pixels visible are a single pixel wide with a single pixel separation, showing that full 4K is delivered accurately."

 

 

By way of comparison, here is what looks to be the same design of test pattern, as displayed on a flat screen 4K television (source: review of Panasonic Viera TH-65AX900A):-


"Switching this off restored my test patterns to perfect, full resolution display (see second image). You aren’t going to see your high-resolution photos look any better for the foreseeable future than on this TV.

 

4K test clean

 

 

 

*                *                 *

 

I don't know whether the blur in the green lines in the image above was due to the camera used for the review article, but if we assume the above image is accurate, and not an artefact of photography, green was not displayed with single pixel resolution.


 

Tonight I've tried with my own TV, a 75" Samsung Q75, getting it to read a thumb drive with the 4K test pattern file downloadable from http://hifi-writer.com/wpblog/?p=4400.  (Although it is only a jpeg file, it has single pixel resolution.)
 

With default settings, my Samsung Q75 does not render the 1-pixel wide green lines clearly when reading the thumbdrive image, interspersing some red between those lines (as I was able to confirm by inspecting the screen with a magnifying glass). It renders the black 1-pixel wide lines very clearly, and the blue and red lines fairly clearly. 


 

The photo below taken of my Q75 screen tonight has sufficient resolution that it reveals the colour subpixels making up the white background. 


 

Care needs to be taken when interpreting the very fine detail of these sorts of images because the physical layout of the subpixels of the camera sensor can interfere a little. (The camera used was a Panasonic DMC-G85).


 

I would still be keen to see a photo demonstrating that single pixel UHD resolution has been achieved using advanced pixel shifting. 


 

As Owen has pointed out, the image in the review article in French does not include the extreme left and extreme right blocks of the standard test pattern that we can assume would have been used. Those missing blocks are where the UHD performance would be tested using lines only a single pixel wide. So the most demanding blocks of the test pattern, arguably the main feature of interest in evaluating the "4K" performance, have not been revealed. 


 


 

Close-up view of 75" Samsung Q75 QLED TV displaying vertical lines of a UHD test pattern:-

 

4ktest-SamsungQ75.png

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All this 4k hype i feel its so overrated..

I have my Panasonic AE8000u, my next upgrade path is unclear...

Needs.

1 lens memory
2 better picture than my Panasonic, but after a significant upgrade in picture quality

4k pixel shiftet or true 4k, thou true 4k is unlikely with the crazy pricing around. Would look at second hand of a great deal comes my way...

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15 hours ago, Perth.hifi said:

All this 4k hype i feel its so overrated..

I have my Panasonic AE8000u, my next upgrade path is unclear...

Needs.

1 lens memory
2 better picture than my Panasonic, but after a significant upgrade in picture quality

4k pixel shiftet or true 4k, thou true 4k is unlikely with the crazy pricing around. Would look at second hand of a great deal comes my way...
 

Go down to your local west coast hi fi store and check out the epson 9400,  you'll be impressed. Under 4 grand too, for that price you can't lose.

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