Mobile engineer & analyst specialized in, display, camera color calibration, audio tuning

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 http://dl.project-voodoo.org/screen-tests/CIExy1931.png 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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Nexus 6P first impressions

I just received a +Huawei Nexus 6P, ordered during Amazon.fr flash sale: 499€ instead of 649€

Screen
– My unit's display exhibit a color shift that's visible enough to be an annoyance with your face right in front: the center and top/bottom do not look the same color tone. More pink in the center, more green off-center.
It's a problem since the display is so large, also both your eyes don't see the same colors since they receive light from the panel at different angles.
When holding the device in hand, you can't keep perfectly in front so the colors vary with angle. It is most apparent with bright UIs, which is the norm nowadays with Material Design.

– White point is a lot greener than it should, as seen often with this technology. It doesn't seem Google/Samsung used an adequate color matching function for AMOLED.
(It's the mathematical model uses to transform spectral light data to perceived color, so you can make two colors look the same on different screen technologies)

– Color over-saturation is more pronounced than previous AMOLED I own/owned. Every color tone becomes so intense it feels nauseous like I ate too much candy.

– sRGB mode that can be activated from Developper settings looks nothing like a sRGB calibrated display. I see why it didn't make it to display settings: it is extremely poor.
I don't imagine anyone being satisfied with it.
Colors look abnormally pale and desaturated, more than they should.
The end result is simply awful.

– Grayscale calibration is not bad on my unit, there's no obvious shift and it scales reasonably well through the brightness scale.

– Black clipping at 3, with rgb (3, 3, 3) being bright enough compared to the extremely deep black so that it introduces artifacts in dark videos.

– There is sharpening. It's slight but present, introducing halos around text fonts.
Entirely unnecessary with a pixel density that high.

Performance
Highest Android performance I've used so far.
It is the first time I observe apps like Maps not drop frames.
Google Play Store still drop frames on basic scrolling operations as it loads network assets however, but less than on other devices.

Speakers
They can get very loud and keep distortion in check.
However I expected a lot better in terms of frequency response.
They still sound tiny: there's no bass, high frequencies are lacking.
At least they're not unpleasant to listen to and offer reasonable clarity.
They could use some EQ tuning.

Camera
– HDR+, even more this time should not be named "HDR"
As you can see in the quick samples attached, the HDR+ image reduces the dynamic range from the normal shot.
It makes poor processing decision in sunny outdoor conditions.

– Automatic white balance and color profile invent colors that do not exist in reality. Typically, yellow/brown tones that should be white or almost gray instead.

Good surprises
– Netflix app gets the 1080p stream.
The video is decoded on a hardware DRM-enabled surface.
(How to check quickly: enable "Invert Colors", the Netflix video content will become all white since the OpenGL compositor can't access the video surface)

– How it wakes up when you pick it up, like Android Wear watch react with movement is a very pleasant addition.

Conclusion
I'm not keeping this unit.
I learned my lessons with keeping AMOLED devices with sub-par panels before.
A couple hours in I don't know yet if I should ask a replacement from Amazon.fr hoping for a better display (but might get the same or worse) – if it's even possible.
I've seen worse AMOLEDs, this one might be good enough for someone not too demanding. It is not good enough to me tho, I know very well what a good AMOLED, unaffected by color shifting is.
Or return for refund, or sell it (I could even make a profit, but it's not the point)

The only thing is that it would be a good development platform for my color correction driver since it really needs better color calibration.
But I'm not yet at the stage where I need more development devices right now.

It's really an underwhelming experience to receive a brand new premium device and.. yeah no. AMOLED quality control is ruining the show again.
Google boasted about the quality of this panel in their AMA, including on its color calibration.
Yeah, in their dreams.

#supercurioBlog #Nexus

In Album Nexus 6P HDR+ reducing dynamic range

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I received the +NVIDIA Shield Android TV!

Ordered on black Friday (160€) with the cheapest free shipping, it got here earlier than I expected.
The device itself is a beauty. It impresses.

I don't have a TV at the moment so it's plugged on a 1920×1200 monitor (supports HDCP) via a HDMI to DVI connector.

On first boot, for the initial setup it configured the output to 1920×1200 (in RGB limited tho) which was fine. It applies an update as soon as it can and is stuck on 640×480 since it rebooted, HDMI settings doesn't allow to change it, shoot.
Maybe something can be hacked until I get a TV.

Its super convenient that there's two Audio Outputs beside the HDMI one that's not connected to anything at the moment.

First output: on the controller. And wow, there's a capable DAC & HP amp in this thing already! Very good surprise, it sounds great.
It's native to the system and I wonder if it's actually streaming in a compressed format or in lossless PCM. I'll measure later. In case it's compressed it's pretty well done.
The output level is sufficient to drive the 300 ohms Sennheiser HD 650 (albeit not super loud for quiet content, but for music it's fine).
The HP amp output impedance appears to be high so the amount of bass is reduced on some headphones.

Second output: on the remote. This one appears as a Bluetooth audio device to the system so it probably streams as SBC.
Unfortunately my unit seems defective. There's a loud permanent icky noise on the left channel that makes it unusable. It persisted after the accessory firmware upgrade so I guess I'll have to request a replacement. Boo.

I got this device to study the possibility to write a color correction driver on this platform.
Either fully hardware using the display controller capabilities – if any or using the (very powerful) GPU.
I expect the GPU and compositor to not be able to access DRM protected surfaces like what Netflix app likely uses, just like on the Nexus 7 2013.
I'll let you know if I get any result, who knows 😊

#supercurioBlog #development #nvidia #shield #TV

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Online accounts creation safety

A few things to keep in mind for mandatory online accounts:

– never create an account if not required in the first place, avoid "surveys" and member cards as much as possible
– use temporary email addresses redirection if it's a one time thing, like from http://jetable.org
– if you have a VPN, enable it before the creation to avoid being geo-localized (you may choose an IP from the same country however)
– unless absolutely required like for shipping address, enter the least information possible.
– unless required to be valid like for warranty or shipping, never hesitate to enter fake name, fake address, fake age, fake everything. Against Terms Of Services? Don't care.
– if you have the ability to pay things with an unique and temporary credit-card, do that.

During your lifetime, you will have no control over the personal information you gave away on yourself.
Hopefully you'll live a fruitful and long life.
Who knows how many websites and services owning data on you will be breached during this lifetime.
That's why the only defense is least info & random fake info.

The VTech breach explained by +Troy Hunt is an excellent example of why you may apply similar rules to yourself (whatever works), your family and teach them as well to your kids since their whole life will be online.

This one is particularly bad because the unique identifier in this very verbose database allows to contact individually every kid on their capable connected toy, by sending messages, pictures.
VTech didn't inform anyone yet. Yes: That bad.

#supercurioBlog #security

Troy Hunt: When children are breached – inside the massive VTech hack

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First consumer grade 360° video camera

+Tony Northrup demonstrates the Ricoh Theta S in this insightful review.
Everyone will find his own usage of course but that's the first video I see from it showing so well how to use this little tool with examples for commercial purposes, family memories or even plain vlogging.

If you find the picture quality sufficient, go ahead!
Otherwise it might be wise to wait for a future product that will record at higher resolution, with sharper lenses, with a little better color profiling.

360° video will get substantially better with 4K overall, including recording on such device: as you can observe, due to the dual circular projection, what is recorded lacks details:
– once transformed geometrically into a 360 video
– once again projected into planar or VR view.

Even with 1080p delivery, higher resolution recording will help.
I don't know about you but I'll certainly get one at some point ☺

#supercurioBlog #VR #video #review

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Vulnerable self-signed root certificates: how many out here?

Since Dell computers shipped with a vulnerable root certificate containing the private key which can be extracted, it is not impossible that other manufacturers do so as well.

And like me, you maybe wonder if it's the case for smartphones too.
Adding this to my TODO list 😊: is there a CTS test for that, do apps exist already to verify all certificates installed on your phone.

#supercurioBlog #security

Dell apologizes for HTTPS certificate fiasco, provides removal tool | Ars Technica
Meanwhile, credential that posed man-in-the-middle threat found on SCADA system.

Source post on Google+

LG partially explains why it canceled the LG Watch Urbane 2nd Edition

"During aggressive testing over thousands of hours under severe conditions, it was revealed that this component failed to meet LG’s quality standards and could potentially impact our image quality over the life of the device."

Since the watch doesn't have a camera, the only "imaging" component is it's display: a 480×480 P-OLED round panel.
The first generation of the Watch Urbane was already prone to display defects appearing with aging. On the second gen, the higher density might make this occur more often.
It could also be adverse effects of rapid burn-in.
Those who received the few first units now know where to look – sort of.

#supercurioBlog #display #OLED

LG says component affecting image quality behind smartwatch recall
A faulty component in LG’s Watch Urbane 2nd Edition, which had the potential to affect image quality, was behind the smartwatch’s removal from sale

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Feature complete Android Malware

This article is an excellent description of "Banker", an Android app designed to use very straightforward and efficient ways to steal all sort of credentials.

It also explains why Google protected several features behind additional permissions in Marshmallow:

– Draw over other apps:
A malware overlays anything it wants on screen, including with a transparent window, invisible but intercepting any touch event: which can let a malware guess everything you touch and type.
Now needs to be activated from the Apps "Configure Apps" settings.

– Apps with usage access:
A malware runs a background service to monitor which application activity is shown in front to the user like every second, and launches an activity or starts an overlay emulating legitimate credential / banking / credit card information request dialog.
Now needs to be activated from the Security settings.

Discussion on Hacker News: https://news.ycombinator.com/item?id=10619675

#supercurioBlog #security

Android malware drops Banker from PNG file
Nowadays is malware trying to hide wherever it is possible to get under the radar of anti-virus companies. Lately I found Trojan dropper carrying malicious payload, encoded by base64, embedded inside an image file. It’s nothi…

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DRAM errors misconceptions

Same address failures trump isolated errors.
And it's a good news, since it allows to blacklist a few error-prone cells to improve RAM reliability much more easily than by swapping the entire hardware components.

However since mobile devices do not use ECC memory, memory errors, leading to crash or corruption stay undetected and non fixable.

Discussion on Hacker News: https://news.ycombinator.com/item?id=10616428

#supercurioBlog

DRAM’s Damning Defects—and How They Cripple Computers
An investigation into dynamic random-access memory chip failure reveals surprising hardware vulnerabilities

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New self-hosted Git repository service

+Sourcegraph looks like an excellent alternative to +GitHub, that you can install on your own server.

I particularly like the IDE-like features making exploring the code so much easier.

It's source code released under "fair source license" is an original approach as well.
It is not exactly "open source" but "hackable source" instead, still much better than the commonplace proprietary.

Discussion on Hacker News: https://news.ycombinator.com/item?id=10621751

#supercurioBlog #development

README.md at b1af2ab4761618930f6f7e44eb775e08fac3f38e – sourcegraph – Sourcegraph
Sourcegraph: the intelligent, hackable code host for teams. Sourcegraph is a self-hosted Git repository service with Code Intelligence. It runs on your own server or cloud and installs in 5 minutes. Sourcegraph gives your team the power to build better software by offering: …

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