closeup photo of 4k pixel grid on tv

closeup photo of 4k pixel grid on tv

[hiro]

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they added white pixels - but that makes fonts less crisp.
cinap was right

i guess there is no way to actually address those pixels individually, the input bandwidth wouldn't be high enough anway.

if anybody else struggles with their 4k tv and rpi4: dont forget to try different refresh rates. this one wanted 50hz instead of 60hz!

(the other one supports both)
-- 
Sent from my Android device with K-9 Mail. Please excuse my brevity.

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Re: [9front] closeup photo of 4k pixel grid on tv

[Steve Simon]

hi,

the up-conversion should increase the pixel density without changing the detail or colours.

i cannot see how plain areas could have modified colours from up-conversion alone but some of the image enhancement in modern TVs have very non-linear enhancers (and sometimes try a little too hard).

try turning the picture “mode” to cinema, and disabling any detail enhancement or deblocking options. if you get nice even colours then try re-enabling the enhancements to work out what is breaking the pictures.

-Steve


> On 5 Jan 2020, at 12:17 pm, hiro <23hiro@gmail.com> wrote:
> 
> they added white pixels - but that makes fonts less crisp.
> cinap was right
> 
> i guess there is no way to actually address those pixels individually, the input bandwidth wouldn't be high enough anway.
> 
> if anybody else struggles with their 4k tv and rpi4: dont forget to try different refresh rates. this one wanted 50hz instead of 60hz!
> 
> (the other one supports both)
> -- 
> Sent from my Android device with K-9 Mail. Please excuse my brevity.
> <IMG_20200105_130518.jpg>

Re: [9front] closeup photo of 4k pixel grid on tv

[hiro]

i'm not sure you mean the same thing, or at least i don't know if it's
valid to call what is happening "up-conversion".

i think the plain areas are fine. and black on white is also fine.

the top bar otoh has some font on a yellow background, and there the
TV does something stupid and makes use of the white pixel, creating an
asymmetry. e.g. the letter 'a' in Plan 9 looks really weird.

my interpretation is that the white pixel is there to increase the
max. brightness, but i could imagine they have a fault in their color
balance, not doing any gamma filtering for the additional subpixel, or
they purposefully sacrificed spatial resolution for color/contrast
with some scheme that i cannot understand.

it's not possible to turn this off, already tried all possible settings.

it's not super problematic for me personally bec. i don't read longer
texts on anything but completely black or white backgrounds.

On 1/5/20, Steve Simon <steve@quintile.net> wrote:
> hi,
>
> the up-conversion should increase the pixel density without changing the
> detail or colours.
>
> i cannot see how plain areas could have modified colours from up-conversion
> alone but some of the image enhancement in modern TVs have very non-linear
> enhancers (and sometimes try a little too hard).
>
> try turning the picture “mode” to cinema, and disabling any detail
> enhancement or deblocking options. if you get nice even colours then try
> re-enabling the enhancements to work out what is breaking the pictures.
>
> -Steve
>
>
>> On 5 Jan 2020, at 12:17 pm, hiro <23hiro@gmail.com> wrote:
>>
>> they added white pixels - but that makes fonts less crisp.
>> cinap was right
>>
>> i guess there is no way to actually address those pixels individually, the
>> input bandwidth wouldn't be high enough anway.
>>
>> if anybody else struggles with their 4k tv and rpi4: dont forget to try
>> different refresh rates. this one wanted 50hz instead of 60hz!
>>
>> (the other one supports both)
>> --
>> Sent from my Android device with K-9 Mail. Please excuse my brevity.
>> <IMG_20200105_130518.jpg>
>
>

Re: [9front] closeup photo of 4k pixel grid on tv

[Steve Simon]

yep, i see what you mean.

i didnt zoom in and didnt realise i was seeing display pixels -my bad.

i think this is a side effect of vertical enhancement. this is my educated guess at what is happening...

the fine horizontal line in the middle of the letter a is enhanced (artificially sharpened) by generating a brighter middle line with dimmer areas above and below.

unfortunately the extra brightness generates a signal that is too bright for the display and this is clipped. the clipping seems to be contant luminance rather than constant hue - hence the white pixel.

the root cause (i think) is the algorithms assume digital signal is proportional to brightness, but for simple graphics this is not true. the tv has a gamma correction curve (mostly historic now) but which makes everything rather non linear.

if your tv has a gamma control and depending on the order of gamma, enhancement, and limiter, you may be able to use this to fix it.

tv is a bit of a pain, thank goodness interlace has (pretty much) gone now.

-Steve


> On 5 Jan 2020, at 4:31 pm, hiro <23hiro@gmail.com> wrote:
> 
> i'm not sure you mean the same thing, or at least i don't know if it's
> valid to call what is happening "up-conversion".
> 
> i think the plain areas are fine. and black on white is also fine.
> 
> the top bar otoh has some font on a yellow background, and there the
> TV does something stupid and makes use of the white pixel, creating an
> asymmetry. e.g. the letter 'a' in Plan 9 looks really weird.
> 
> my interpretation is that the white pixel is there to increase the
> max. brightness, but i could imagine they have a fault in their color
> balance, not doing any gamma filtering for the additional subpixel, or
> they purposefully sacrificed spatial resolution for color/contrast
> with some scheme that i cannot understand.
> 
> it's not possible to turn this off, already tried all possible settings.
> 
> it's not super problematic for me personally bec. i don't read longer
> texts on anything but completely black or white backgrounds.
> 
>> On 1/5/20, Steve Simon <steve@quintile.net> wrote:
>> hi,
>> 
>> the up-conversion should increase the pixel density without changing the
>> detail or colours.
>> 
>> i cannot see how plain areas could have modified colours from up-conversion
>> alone but some of the image enhancement in modern TVs have very non-linear
>> enhancers (and sometimes try a little too hard).
>> 
>> try turning the picture “mode” to cinema, and disabling any detail
>> enhancement or deblocking options. if you get nice even colours then try
>> re-enabling the enhancements to work out what is breaking the pictures.
>> 
>> -Steve
>> 
>> 
>>>> On 5 Jan 2020, at 12:17 pm, hiro <23hiro@gmail.com> wrote:
>>> 
>>> they added white pixels - but that makes fonts less crisp.
>>> cinap was right
>>> 
>>> i guess there is no way to actually address those pixels individually, the
>>> input bandwidth wouldn't be high enough anway.
>>> 
>>> if anybody else struggles with their 4k tv and rpi4: dont forget to try
>>> different refresh rates. this one wanted 50hz instead of 60hz!
>>> 
>>> (the other one supports both)
>>> --
>>> Sent from my Android device with K-9 Mail. Please excuse my brevity.
>>> <IMG_20200105_130518.jpg>
>> 
>> 

Re: [9front] closeup photo of 4k pixel grid on tv

[hiro]

yep. no options for that, no gamma control or anything.

interesting to see their poor little tricks to make the TVs bright
enough. painful to imagine how many customers/victims are falling for
such simple benchmarks and then forever wondering why the quality got
worse.

i don't think it's possible to use it for photo editing, but text and
highly compressed video junk from hollywood should fit this technology
perfectly. i'm happy they optimized for brightness as (unlike the
target group) most of my screen is white normally, haha.

if you count VGA chars per dollar it's a good price, it was only 160 bucks.

i had nearly sent back the TV bec. of the non-standard unexpected 50Hz
requirement, but the support guy from this little
reselling/relabeling? company was competent enough to point out the
exact thing i was missing. he wasted no time, 1 line email to him, 1
line back, problem solved.

so nice to have little companies still, even if the product they are
responsible for is objectively such a low quality, in comparison to
the marketing i heard about the competition at least.

i never thought i'd ever be in the place where i have so many pixels
in abundance, more than i will ever need on a display. this most
boring, gradual technology advance is nonetheless the most amazing to
me in practice, haha.

may all catclocks be ALL OVER YOU and protect all your pixels, and
have a good day.

On 1/5/20, Steve Simon <steve@quintile.net> wrote:
> yep, i see what you mean.
>
> i didnt zoom in and didnt realise i was seeing display pixels -my bad.
>
> i think this is a side effect of vertical enhancement. this is my educated
> guess at what is happening...
>
> the fine horizontal line in the middle of the letter a is enhanced
> (artificially sharpened) by generating a brighter middle line with dimmer
> areas above and below.
>
> unfortunately the extra brightness generates a signal that is too bright for
> the display and this is clipped. the clipping seems to be contant luminance
> rather than constant hue - hence the white pixel.
>
> the root cause (i think) is the algorithms assume digital signal is
> proportional to brightness, but for simple graphics this is not true. the tv
> has a gamma correction curve (mostly historic now) but which makes
> everything rather non linear.
>
> if your tv has a gamma control and depending on the order of gamma,
> enhancement, and limiter, you may be able to use this to fix it.
>
> tv is a bit of a pain, thank goodness interlace has (pretty much) gone now.
>
> -Steve
>
>
>> On 5 Jan 2020, at 4:31 pm, hiro <23hiro@gmail.com> wrote:
>>
>> i'm not sure you mean the same thing, or at least i don't know if it's
>> valid to call what is happening "up-conversion".
>>
>> i think the plain areas are fine. and black on white is also fine.
>>
>> the top bar otoh has some font on a yellow background, and there the
>> TV does something stupid and makes use of the white pixel, creating an
>> asymmetry. e.g. the letter 'a' in Plan 9 looks really weird.
>>
>> my interpretation is that the white pixel is there to increase the
>> max. brightness, but i could imagine they have a fault in their color
>> balance, not doing any gamma filtering for the additional subpixel, or
>> they purposefully sacrificed spatial resolution for color/contrast
>> with some scheme that i cannot understand.
>>
>> it's not possible to turn this off, already tried all possible settings.
>>
>> it's not super problematic for me personally bec. i don't read longer
>> texts on anything but completely black or white backgrounds.
>>
>>> On 1/5/20, Steve Simon <steve@quintile.net> wrote:
>>> hi,
>>>
>>> the up-conversion should increase the pixel density without changing the
>>> detail or colours.
>>>
>>> i cannot see how plain areas could have modified colours from
>>> up-conversion
>>> alone but some of the image enhancement in modern TVs have very
>>> non-linear
>>> enhancers (and sometimes try a little too hard).
>>>
>>> try turning the picture “mode” to cinema, and disabling any detail
>>> enhancement or deblocking options. if you get nice even colours then try
>>> re-enabling the enhancements to work out what is breaking the pictures.
>>>
>>> -Steve
>>>
>>>
>>>>> On 5 Jan 2020, at 12:17 pm, hiro <23hiro@gmail.com> wrote:
>>>>
>>>> they added white pixels - but that makes fonts less crisp.
>>>> cinap was right
>>>>
>>>> i guess there is no way to actually address those pixels individually,
>>>> the
>>>> input bandwidth wouldn't be high enough anway.
>>>>
>>>> if anybody else struggles with their 4k tv and rpi4: dont forget to try
>>>> different refresh rates. this one wanted 50hz instead of 60hz!
>>>>
>>>> (the other one supports both)
>>>> --
>>>> Sent from my Android device with K-9 Mail. Please excuse my brevity.
>>>> <IMG_20200105_130518.jpg>
>>>
>>>
>
>

Re: [9front] closeup photo of 4k pixel grid on tv

[Ethan Gardener]

On Sun, Jan 5, 2020, at 4:30 PM, hiro wrote:
> 
> it's not possible to turn this off, already tried all possible settings.

That's a shame. I can set my 4k screen to "scenery" mode to see nice crisp text, although I admit I haven't tried it with rpi/plan 9. "Text" mode is awful, by the way, can barely see the characters. ;) It's an Asus, 28", possibly the cheapest 4k they do. It's not great, colors change with viewing angle, but I bought it for text.

Re: [9front] closeup photo of 4k pixel grid on tv

[hiro]

yeah, the one i got is definitely not TN, so it has good viewing
angles. apart from price and resolution that was my only requirement.
it's possible to get very good value nowadays.

since it's a tv and so big, i'm sitting far away anyway, and the only
thing i care that much about to be crisp is black on white text. so i
would be good even if i sat quite near.

in the meantime i got a little surprise accident shipment from amazon.
instead of something else that i had ordered they got confused and
sent me instead a usb-c adaptor to hdmi that is able to pass through
4k@59Hz from some laptop.
lessons:

1) if 60hz doesn't work, but 59hz does, perhaps rpi hdmi output SNR
was just a *little* too low and 5/6 bandwidth from the 50hz mode gets
it to be just low enough to still work.
next thing to try: increase rpi4 hdmi output signal power (there are
some config.txt options)
2) it must be an *active* usb-c DP alternate mode->HDMI adaptor of
some sort, bec. HDMI output bandwidth of the igpu is actually too low
for 4k@59Hz (yes, intel still has this problem and they seem not to
care or notice). DP would be high enough.
i had tried really hard to find exactly such type of active adaptor on
amazon and ebay, but it's impossible to find. most such adaptors are
just forwarding hdmi signals directly from the gpu without conversion,
and it's never specified in the technical data which strategy they
use. e.g. i already had bought 2 adaptors and they don't do any
conversion, so the igpu limits the hdmi output to 4k@30hz. this makes
mouse movements so laggy as to be completely unusable. so i got very
lucky amazon accidentally sent me what i needed anyway. funny, eh?

i would recommend these cheap kinds of 4k TVs to anybody, if intel
didn't fuck up their igpu's HDMI output bandwidth, or if it was
possible to get the right adaptors easily.
since neither is the case you are in for quite some experimentation
unless you get a proper monitor (that isn't a PC) bec. they al come
with less problematic DP input.

On 1/16/20, Ethan Gardener <eekee57@fastmail.fm> wrote:
> On Sun, Jan 5, 2020, at 4:30 PM, hiro wrote:
>>
>> it's not possible to turn this off, already tried all possible settings.
>
> That's a shame. I can set my 4k screen to "scenery" mode to see nice crisp
> text, although I admit I haven't tried it with rpi/plan 9. "Text" mode is
> awful, by the way, can barely see the characters. ;) It's an Asus, 28",
> possibly the cheapest 4k they do. It's not great, colors change with viewing
> angle, but I bought it for text.
>

Re: [9front] closeup photo of 4k pixel grid on tv

[hiro]

s/that isn't a PC/that isn't a TV/