[One (M7) General] puremind:
HTC One Display Brightness

The HTC One uses an adaptative contrast mechanism for the screen brightness that is in operation even when auto-brightness is off. This mechanism means that brightness settles after each picture change only after a 4-5 seconds, which means that measurements that are taken too quickly can overestimate brightness by 15%, which is why there is a wide fluctuation across all reviews.

At which level brightness settles depends on the average picture level. You can sometimes observe this while browsing: when the content displayed varies between dark and bright content, an adjustment is visible.

In my measurements below, I have indicated the brightness range as well as the typical settled brightness for the standard 100% Voodoo test pattern.

HTC One Black Levels

Like with brightness, black levels also fluctuate due to the adaptative contrast mechanism:

Content with darker average picture level will be dimmed

Content with brighter content will will brightened

Overall black levels will fluctuate between 0.29cd/m² and 0.55cd/m², so dynamic contrast will be around 1700:1 whereas ANSI (or intra-picture contrast) will be around 1000:1.

Color Temperature: Three phones, three different display calibrations.

Unit 1 (silver)

Fabricated on 12th March 2013 at factory Tierra del Fuego Factory in Argentina (Serial: FA33CWxxxxxx, Panel ID JDI C2_2)

Display: color temperature slightly on the cool side

White color temperature: 6950K (some meters will incorrectly measure this up to 350K higher, especially if not using the right spectral file for the type of display)

Black Level: 0.37cd/m² to 0.50 cd/m²

Black Level (typical voodoo test pattern): 0.43 cd/m²

White Point: 370cd/m² to 490cd/m²

White Point (typical voodoo test pattern): 435cd/m²

Typical Contrast (without adaptative mechanism): 1000:1

ANSI Contrast: 1100:1
​

Unit 2 (silver)

Fabricated on 3rd April 2013 at Hsinchu, Taiwan factory (Serial: HT343Wxxxxxx, Panel ID JDI C2_2)

Display: neutral color temperature, slightly lower contrat:

White color temperature: 6550K (some meters will incorrectly measure this up to 350K higher, especially if not using the right spectral file for the type of display)

Black Level: 0.50 cd/m² to 0.64cd/m²

Black Level (typical voodoo test pattern): 0.52 cd/m²

White Point: 400cd/m² to 530cd/m²

White Point (typical voodoo test pattern): 466cd/m²

Typical Contrast (with adaptative mechanism): 900:1

Typical ANSI Contrast: 970:1
​

Unit 3 (black)

Fabricated on 12th April 2013 at factory Tierra del Fuego Factory in Argentina (Serial: FA34CWxxxxxx, Panel ID JDI C2_2)

Display: Even cooler color temperature unit 1 but same brightness and contrast

White color temperature: 7200K (some meters will incorrectly measure this up to 350K higher, especially if not using the right spectral file for the type of display)

Black Level: 0.37cd/m² to 0.50 cd/m²

Black Level (typical voodoo test pattern): 0.43 cd/m²

White Point: 370cd/m² to 490cd/m²

White Point (typical voodoo test pattern): 435cd/m²

Typical Contrast (without adaptative mechanism): 1000:1

ANSI Contrast: 1100:1
​

Comparison of warmest color temperature on Unit 2 (left) vs. coolest on Unit 3 (right):

Based on the collective reviews of the HTC One including my own measurements, it is now clear that HTC One displays can have different display characteristics in terms or color temperature, contrast and brightness. Even displays with the same Display ID have can have widely fluctuating brightness and color temperature depending on factory calibration.

Settled brightness between 390cd/m² and 475cd/m²

Color Temperature between 6550K to 7350K

ANSI contrast between 930:1 and 1100:1

Currently available reviews for the HTC One Display

Neutral Color Temperature

20.03.2013 GBR pcpro: 481cd/m² brightness | 1202:1 contrast (measured with i1 Display Pro)

20.03.2013 DEU Computerbase.de: 483cd/m² brightness | 1100:1 contrast | 6,600K white temperature (measured with DTP94)

26.03.2013 FRA 01net.fr: 485 cd/m² | 0,29 cd/m² | 1679:1 contrast | 6638K white temperature (measured with Minolta CA-210 and DTP94)

26.03.2013 FRA Puremind@xda (see below): 466 cd/m² | 0,52 cd/m² | 939:1 contrast | 6650K white temperature (measured with i1 Pro 2)

Medium-High Color Temperature

26.03.2013 DEU puremind@xda 463cd/m² brightness | 1073:1 contrast | 6934K white temperature (measured with i1 Pro)

02.04.2013 DEU notebookcheck.com: 488.9cd /m² brightness | 0.23 cd / m² black level | 2117:1 contrast | 7205K white temperature

26.02.2013 RUS 3dnews.ru: 382cd/m² and 1,258:1 contrast | 6,938K white temperature (measured with Spyder 4)

High Color Temperature

14.03.2013 GBR uk.hardware.info: 426cd/m² brightness | 977:1 contrast | 7,820K color temperature (measured with i1 Display Pro)

26.02.2013 RUS 3dnews.ru: 453cd/m² and 1,328:1 contrast | 7,598K white temperature (measured with Spyder 4)

14.03.2013 NLD Tweakers.net: 489cd/m² | 1159:1 contrast | 8,166 color temperature (measured with i1 Display Pro)

26.03.2013 DEU puremind@xda 420cd/m² brightness | 1060:1 contrast | 8,130K color temperature (measured with Chroma 5)

28.03.2013 RUS high-tech@mail.ru 492cd/m² brightness | 1189:1 contrast | 7980K white temperature

Unknown color temperature:

14.03.2013 USA laptopmag: 463cd/m² brightness

19.03.2013 DEU Notebookjournal: 385cd/m² and 1100:1 contrast

19.03.2013 DEU PC Welt 447cd/m² brightness | 1711:1 contrast

20.03.2013 DEU Chip.de: 479cd/m² brightness | 1020:1 contrast

21.03.2013 FRA Les Numériques 460cd/m² | 1568:1 (measured with i1 Pro or i1 Pro 2 tbc.)

21.03.2013 FRA 01.net 480cd/m² brightness | 1,655:1 contrast (measured with Konica Minolta CA-210)

23.03.2013 BGR GSMArena: 647cd/m² brightness | 1541:1 contrast

Having said that, there are still different display calibrations out there, I myself measured "settled" brightness

I will try and keep this updated with new tests to confirm where each screen type can be found.

For reference, here are the luminance ranges of the color testing devices listed above.

i1 pro__________________________ 0.20 cd/m² to 300 cd/m²

i1 pro 2_________________________0.20 cd/m² to 1200 cd/m²

Chroma 5/Sencore Color Pro V_______0.01 cd/m² 1000 cd/m²

Spider 3/4_______________________0.02 cd/m² 5000 cd/m²

i1 Display 2______________._____._.__0.02 cd/m² 3000 cd/m²

i1 Display 3/i1 Display Pro/C6___._____0.003 cd/m² 1200 cd/m²

Konica Minolta CA-210______________0.01cd/m² 1000 cd/m²