how to use opple light master

dzwdev

i bought an opple light master but there is no use guide with it

to measure the pwm for a phone or laptop or a bulb how much the distance should be between the device and the target? is it better to measure pwm of phone with a black picture or a white one? do i have to turn off lights?

madmozg

On white background to see the precise PWM waves and see when the display turn on and off
On gray background, to see how the display behave with darker images
Its good to test at night or where there is no other lights sources.
I'm putting light master pretty close to laptop screen or a phone.

dzwdev

i tested it with redmi 10 2022 and dell latitude 7480 and heawei p10

all of theme according to the app have no pwm flickering

but when i use p10 i get hurt in my eyes and i feel pain in my brain. i thought it was because of pwm, but it seems there is another problem that causing the big pain to me when using that phone? in contrast: when i use readmi 10 i have no pain.

simplex

dzwdev when i use p10

my huawei p10 ( VTR-L09, android 8 ) works fine from 2018 year, display without issues and eye-strain/headache.

I bought new, not used, are you sure your screen is original?

dzwdev

simplex i also have VTR-L09 with android 9 MEUI
i bought it used, I'm not sure if the screen is original.

simplex

dzwdev if the screen is original

I suppose is the key. Do you know how to check panel inside android phone without tear-down?

Its sad but buying used "good for eye" phone not guaranteed to get "no flickering" original display inside

dzwdev

simplex

"Do you know how to check panel inside android phone without tear-down?"

I opened the phone back cover, but the screen is in the other side.

according to this video i need to use heat to remove the screen to read the information and this is risky.

dzwdev

i think the app has a bug? in the graphic chart the point is in the red area which means that it is risky but it print: no risk?
i tried that with several bulbs:

and what is "modulation depth" and "flicker index"? is it better to be slower or higher?

https://ibb.co/DkpxyrQ

(when i try to upload the image directly to the reply it shows a long text and not an image)

ryans

I also purchased one. Interestingly an incandescent bulb (US power) shows 'high risk' (no symptoms):

While my corporate HP EliteBook 840 G6 with Windows 10 21H2 shows 'no risk' showing a white background and I do get mild symptoms:

The device does not seem very precise as I sometimes get very different measurements. I would only begin to trust a median of many measurements.

dzwdev

ryans
"The device does not seem very precise as I sometimes get very different measurements. I would only begin to trust a median of many measurements."
I'm in the same situation.
i'm still confused about huawei p10: i tried several times and almost of theme i get: no risk with 0 flickering i tried with black image and with white one in absence of other light sources, but that phone is very harmful to me.

simplex

dzwdev no risk with 0 flickering

all graphics are ppl-average feeling of test groups. All you need - to get lower modulation % and higher freqs, smooth meandr PWM view.

If PWM is good but device is unusable - there is also dithering issues (software), LED backlight spectrum in UV zone (screen hardware), dithering (software) + pixel inversion (hardware) resonance

dzwdev

simplex
"all graphics are ppl-average feeling of test groups. All you need - to get lower modulation % and higher freqs, smooth meandr PWM view." i did not understand this. i hope that you can explain.

the dithering issues is not detectable with opple flickering test?
how to detect pixel inversion and LED backlight spectrum in UV zone?

according to notebookcheck.net: huawei p10 has LTPS screen. may the the technology of this screen is causing me that big pain?

simplex

dzwdev i hope that you can explain.

Opple engeneers place graphics with zones, how did they know where is red and where is green? Some test group of people sits in 1 place, then engeneers show them different flickering types, and test group push button "I can see" or "I cannot see". Then data collected show avg zones, but this is average results of test group, your personal results could be higher or lower or equal. Thats why I only use modulation depth from 1st page, and waveform type from 2nd page

dzwdev the dithering issues is not detectable with opple flickering test?

Correct

dzwdev how to detect pixel inversion and LED backlight spectrum in UV zone?

Regarding pixel inversion - at least I know 2 pattern types, I not sure how many types engeneers use. Also idk inversion frequency (if they flicker 120 times per second, you need 120fps camera with 1/120 shutter, if they flicker 1200 times… hope ou got the idea), in laptop panel (which have backlight + liquid crystals sandwich together) datasheets I also found nothing, only PWM freq range - from 200 to 1000hz

LED backlight spectrum in UV zone - not sure standart screen calibrator can show such data (100…400nm range)… which UV range you need… UVA, UVB? you need something like that

dzwdev huawei p10 has LTPS screen. may the the technology of this screen is causing me that big pain?

all you need - to get display model of your, to compare for mine p10

jen

The Opple meter is better than nothing, but tricky to use and quite limited in usefulness. My experience is that it's good to have as a quick check for particularly bad flicker that I can carry with me all the time, but it's not good enough to measure the flicker of lower-flicker lights that injure me, and for screens is only good enough for extreme flicker, such as significant backlight flicker.

See the IssuesWhenMeasuringLightFlicker_Public slideshow here for an analysis of the Opple meter and hints on how to best use it:
https://www.flickersense.org/testing-leds-and-screens

I use a professional flicker meter in most situations, Slow-motion videos (with a microscope for screens) are also helpful for attempting to measure color flicker. Note that I suspect color-to-color flicker may be significant in terms of triggering brain injury for me. Incandescents don't have color-to-color flicker - perhaps why their flicker is more tolerable to me and to a lot of us here. Flicker meters don't distinguish between the flicker of different colors of light.

Also, the "risk" graph shouldn't be used to infer safety - it's unfortunately extremely misleading. It's a graph based on estimates of flicker visibility based on a handful of normal observers with no history of any neurological condition. It isn't based on any health data at all for flicker at or above 100 Hz. Data underlying the IEEE flicker "risk" graph is discussed here: https://www.flickersense.org/led-health-effects/flicker-100-hz-scientific-literature

dzwdev

jen
thank you for your professional important reports and data.

it seems that the topic is complicated. and it is hard to find a proper phone not hurting eyes and brain.

simplex

dzwdev i need to use heat

yep, very complicated method. Maybe some apps can show panel ID in android, idk

dzwdev

simplex

i think that there is no opportunity till now to read screen info from the system.

can you test please if your phone send UV lights?

ensete

Also you issue might have nothing to do with flicker or PWM. It's not always the case, and with many people a complete red herring

dzwdev

ensete

yes, i start thinking that the problem is not in pwm

i was using a galaxy s6 before which has an amoled screen, and i did not have problems with it

there was something special in that phone: it has a filter in top of its screen, I'm not sure of it but i think it is a UV filter. (one time i opened it because of a screen problem then the motherboard was broken by mistake) .

the problem may be in UV light emitted by other phones. i will try to test that UV problem and post any new results.

simplex

dzwdev can you test please if your phone send UV lights?

If you know how, I can check!

look:

https://www.gizchina.com/2019/04/03/oppo-announces-dc-like-dimming-feature-for-coloros/

https://ebics.net/does-dc-dimming-of-oled-screen-really-work/

software DC dimming emulation smooth gray layer with original colors using… dithering

dzwdev

simplex
thank you. i will check it.

https://www.youtube.com/watch?v=A_S6pL5pznA

in this video he shows that the screen has a glass layer and a polarized layer. the top one of theme seems like having an effect in light, i tested to put in in top of p10 and the light is less harmful but i cant use the touch screen so i couldn't test it well.