Nexus 6P display measurements, standard mode

With a comparison between maximum brightness and approx 100 cd/m² in order to evaluate the calibration curves scaling.

Average gamma values:
Max (366 cd/m²): 2.37
100 cd/m²: 2.32

Short analysis today due to lack of time:

– The curves, measured with a 256-precision are smooth which indicates the absence of banding in the grayscale.

– The color gamut is extremely large, and color saturation is increased further by the higher gamma: as you can see in the CIE 1932 diagrams, the saturation points are not spaced evenly.
Visual inspection of shows color clipping due to the color processing present to increase color saturation.
Boosting color saturation on such a wide-gamut display is undesirable.

This is the first Nexus AMOLED device boosting color saturation. I wonder if it's intentional or something inherited from the panel supplier default setup.
The color saturation levels are so extreme that I would qualify this color rendition behavior as a bug and encourage to file it as such.

– On slightly lower brightness levels like measured at 100 cd/m², the shadows on this unit become a lot darker, quickly reaching below the minimum the i1 Display Pro sensor used here can read.

– Grayscale RGB levels tracking on this unit is better at 100 cd/m² than at maximum brightness.
This is the reverse of older AMOLED brightness scaling I had experience with, where maximum brightness was the most accurate.
This may vary between units, but it's worth mentioning that lower brightness levels doesn't necessarily equates to reduced color accuracy.
Although this remark is valid for midrange and highlights, the situation tends to degrade in shadows.

– RGB Levels:
Red is lacking.
The colorimeter here can't see things exactly like your eyes: a correction would be required due to the AMOLED spectral characteristics but it still gives an idea with red lacking compared blue and green, compared to a standard target of Natural Daylight D65, which is neither yellow, blue or green, nor warm or cold but average daytime neutral white.
Since our vision is most sensitive to green, it is apparent.
Also since the color temperature formula, giving a warm/cold indication essentially ignored the green component, it is not reflected in the grayscale temperature curves values.

The decision (or oversight) to boost color saturation using color processing by default really leaves me perplex.
Measurements confirms my subjective first impressions 😉

#supercurioBlog #display #color #measurements #analysis


In Album Nexus 6P #1 display measurements, standard

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Black and white in color trick

It's amazing how many seconds the effect lasts (and how true they appear) as long as you keep looking precisely at the dot.

In case you were wondering if you can use your eyes as instrument to calibrate displays, well.. let's say they're not the best tool for that 😀
– You can't access the RAW data from the sensors
– There's too much processing in the brain and even before that at the biological level.

Fascinating 🙂

Via +PetaPixel

#supercurioBlog #color #video #vision

Source post on Google+

10-bit color on OSX El Captain

The first thing.. okay the second thing I noticed when looking at a couple Retina iMac was the large amount of banding in gradients.
Like this one:×1600.png or a dithered version×1600-oversampled-dithered.png

It seems that Apple was applying a correction profile on only 8-bit – and quite a bit of it, which on this very large and sharp panel created simply banding galore.

10-bit, even for apps that support only 8-bit per channel (24-bit colors) should at least fix the calibration banding issue, if all is as it should be.

#supercurioBlog #color #calibration #banding

Originally shared by +PetaPixel

OS X El Capitan Quietly Unlocked 10-Bit Color in iMacs and Mac Pros

OS X El Capitan Quietly Unlocked 10-Bit Color in iMacs and Mac Pros
OS X El Capitan added some major features to the operating system when the update was released at the end of September 2015, but it appears that there was

Source post on Google+

Here's the results of the current state of my display calibration algorithm on the early batch Nexus 5 I sent back and its refurbished replacement

Following up on

On both, a 12-bit RGB LUT is loaded in hardware, but as you can see on the curves in these graphs, the panel being only 8-bit, there's some banding going on.
I started working on another driver approach that allows to avoid this 8-bit limitation and permits extremely precise correction.

The target for both is D65 white point (as seen by the sensor for simplification), gamma 2.2 curve with a fine-tuned near-black response to avoid clipping or visual artifacts in shadows and near black, also preserving the color balance as much as possible near black.

The replacement Nexus 5 stays better even when both are calibrated thanks to its higher native brightness, slightly higher contrast ratio, and better consistency in its RGB channels which requires less correction.
Although beside the brightness difference which is appreciable, they look the same.

On both, the grayscale Delta E stays below 1 which is a very good accuracy despite the current 8-bit per channel driver hardware limitation.

Subjectively, it also looks pretty darn good 🙂

Other info:

Maximum brightness – significant difference
original: 381 cd/m², replacement 474 cd/m²

Contrast ratio
original: 862:1, replacement: 891:1

On both, HCFR calculates an average gamma value of 2.18 without black point compensation and 2.21 with.

#supercurioBlog #calibration #display #color #development #measurements


In Album Display Measurements: my calibration algorithm on first batch Nexus vs refurbished replacement

Source post on Google+

A few days ago I sent back my Nexus 5, from the first batch shipped to France for a defect behind the glass lens

The replacement unit I received immediately seemed to have a better and brighter display, which is confirmed by the measurements graphs attached.

The replacement is brighter, with warmer white point, its RGB channels curves response are a lot closer across the board.
From comparing two phones, I can't tell if one is just better than the other or if Google improved the factory calibration process.

Neither display's white look like D65 daylight white compared to actual daylight or a reference CRT monitor (regardless of the sensor used).

Other info:

Maximum brightness – significant difference
original: 409 cd/m², replacement 510 cd/m²

Contrast ratio – about the same
original: 926:1, replacement: 952:1

Average gamma – interestingly about the same despite the difference in curves
original: 2.07, replacement: 2.08

Up next: results calibrated 😉

#supercurioBlog #calibration #display #color #measurements


In Album Display Measurements: first batch Nexus 5 vs refurbished replacement

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There's a new revision of the popular X-Rite i1 Display Pro colorimeter out here, and the latest ArgyllCMS release is not able to drive this sensor fully yet

+Vincent Sergère is a proud owner of one and can't use it quite yet for what it's intended for now.

Hoping this message will help ArgyllCMS's author!

#supercurioBlog #development #color #calibration

[argyllcms] Error with new i1 Display Pro revision – argyllcms – FreeLists
[argyllcms] Error with new i1 Display Pro revision. From: François Simond ; To: [email protected]; Date: Fri, 9 Oct 2015 02:29:27 +0200. Hi Graeme and the list! I’m assisting a friend with his brand new X-Rite i1 DisplayPro, which has a new revision and firmware.

Source post on Google+

A few small errors in comparisons methods, like:

– Comparing still images at 100% zoom for different sensor resolutions instead of normalized resolutions.
– Comparing still images taken at a different focal length / field of view.

But still an interesting video from +SuperSaf TV!
The +Sony Xperia Z5 does a good job at stabilization, especially in 1080p video.
It's a shame that 4K video recording doesn't benefit from the same stabilization quality, although there's still some.
As it's digital stabilization only however, you'll often see some artifacts coming from the motion blur due to movement in frames.

The Z5 also does a good job at stabilizing the front facing camera although it's at the expense of some artifacts and crop, is there no such capability on the Galaxy S6?

Galaxy S6 front and back lens are very good at dealing with flare, which is not the case with the Z5.

The Z5 color profile and automatic white balance is colder, as usual with +Sony products.

Galaxy S6 appears to be more reliable and consistent overall than the Z5, which can sometimes get the automatic white balance all wrong like at 4:57 (it gets a nuance of green as white reference, hence the whole scene turning into almost greyscale)

#supercurioBlog #camera #color #comparison

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So yeah, why lasers?! You may ask.
A cinema projector is supposed to display intergalactic ships, not shoot them down.

The reason motivating using lasers is driven by the UHD standard and its Rec. 2020 color gamut.
Rec. 2020 colorspace gamut red green and blue primaries are single wavelength colors.
That's how you can render the most intense saturated colors. More intense and saturated than any AMOLED or LCD with Quantum Dots.

Lasers, by nature are this single wavelength light source and thus are just what's needed to render the whole Rec. 2020 gamut when you mix three of them.

Because we're still talking only about making colors by adding variable amounts of 3 primaries, Rec. 2020 gamut doesn't include all colors visible by your eye. For that you would need more than 3 primaries.

It's possible to speculate than Rec. 2020 will be large enough that we might never go further than that by adding more single wavelength primaries and cover even more of the visible light.
But who knows, that might become the next marketing argument at some point 😁

TV manufacturers are also preparing laser backlight LCDs units.
We're not sure yet if they'll reach the public due to power efficiency concerns.
The wide gamut TVs you'll be able to buy, covering not the whole Rec. 2020 gamut but a good portion of them might stay AMOLED or LCDs + Quantum dots.

Between HDR high brightness and full Rec. 2020 support, be sure the future will have everything needed to massage your retinas just right.

#supercurioBlog #color #video

IMAX with laser: Superb contrast, 4K resolution, and huge color gamuts | Ars Technica
Ars checks out Europe’s first IMAX laser cinema.

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Nexus 6P AMOLED panel info

"SW: It has a Samsung WQHD AMOLED panel. We have spent a lot of time tuning the white-point and color gamut for these panels – hope you will enjoy the accuracy of the display."

"Yep, confirmed: Nexus 6P has the latest generation panels from Samsung. One of things we deeply care for is the quality and accuracy of the display through which all of us connect with the stuff we care about. We created a very tight spec (white-point temperature, delta-E variance, color-space accuracy, etc) for the 6P WQHD AMOLED panel, so it was important that we use the most cutting edge panel technology available."

That sounds good, and especially after +Dave Burke​​​​​​​​​​ claimed on stage that the display was "very vibrant", this promise of color accuracy will need independent verification 😉

Note that this answer doesn't specify to which color space or white point they decided to conform.
This display will show near exclusively content encoded to sRGB standard (which specifies the white point and RGB primaries, gamut and electronic-optical transfer function – aka EOTF aka gamma curves).
In case the display colorspace they chose is wide gamut, any color accuracy claim is automatically moot given the fact Android doesn't support color any management at the moment.

There are various ways to calibrate a wide gamut AMOLED to conform to sRGB specifications tho: using the panel's factory calibration in conjunction with either:
– the panel's color tuning
– Qualcomm Mobile Display Controller image processing, with basic colorspace conversion or 3D LUT
– the GPU (which taxes some GPU power however)

#supercurioBlog #display #color #calibration #Nexus

Hi, I’m Hiroshi Lockheimer, here at Google with the team that build Nexus 5X & 6P…Ask Us Anything! • /r/IAmA
Yep, confirmed: Nexus 6P has the latest generation panels from Samsung. One of things we deeply care for is the quality and accuracy of the…

Source post on Google+

Okay so calibrating the +Sony Smartwatch 3 display colors is gonna be tricky given how the measurements come out

Calculated from data: contrast ratio of 8:1.. yeah, nope that's not right ^^

However you can see quickly why colors on this display look so strange: the blue channel is way off and clips at IRE 82.
It might be a deliberate attempt of the people who profiled the panel to make it appear colder blue than the white point really has.
As you can see on the RGB Levels graph, there is tha much deviation between channels. If you saw the watch display in real life: you probably knew already.

I don't know yet what is it that makes darker values brighter than they should: it might be a content adaptive brightness algorithm tuned for readability.
As seen on the CIE Diagram there might be some more color processing going on as well.

The small size of the display is compared to the size of the X-Rite i1 Display Pro is not making things easy, I'll try tuning my patterns and using the i1 Pro instead.

Well, you gotta start somewhere right?

#supercurioBlog #calibration #color #display


In Album First attempt at measuring Sony Smartwatch 3 display

Source post on Google+