Early measurements results of a +Sony Xperia Z2, captured from +Erica Griffin computer screen as she couldn't wait to see the results

I'm impressed by the capabilities of this device so far.
Gamut is large, comparable to Super AMOLED displays.
On the Z2 devices demonstrated in Barcelona, there's no chroma saturation boost added. If color seem plenty intense they don't look too over-saturated like we've seen often on Samsung wide gamut panels.

A bit later I'll publish the full measurements corrected based on a reference spectrophotometer, for precise color temperature and gamut evaluations.
Also, planned : wavelength spectrum to look even more in depth into this new +Sony backlight technology!

#supercurioBlog #display #measurements #MWC


In Album 2/24/14

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Currently measuring +Sony Xperia Z2 display :-)

You can see in this picture my exclusive analysis rig.

There's some dynamic contrast going on but besides that I can tell you already that Sony stepped up big time in panel quality compared to the Z, Z1 but also Z1 compact and Z Ultra.

#supercurioBlog #display #color #measurements


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I'm listening a lot of music from Play Music All Access lately, at the maximum bitrate which is 320kbit/s LAME mp3

And when I stumble upon a song or an album I've been used to listen to in lossless/FLAC, I'm like hmm no that's not quite it.

I wonder if I would be able to discern random samples using the same codec & bitrate and lossless in ABX test.
Maybe it makes a difference when you know a song very well in it's original lossless format already.

I would describe the main difference being in:
– impact of drums, typically snare drums and cymbals
– some flanger effect and loss of temporal resolution in vocals
– loss of resolution in synthetic instruments like those found in electronic music like trance or dubstep, or practically everything shaped like a square or triangle wave.

I still think All Access is probably the best sounding streaming service, and content discovery is great but boy I would like to be able to stream lossless instead. It's not the same experience.

Also I don't recommend to spend days listening to samples of every available audio compression codecs at various bitrates in order to find the transparency sweet spot for them.
Because you can't un-train your ear after that, too late ^^

#supercurioBlog #audio #streaming #compression #codec

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Eddie Sinnott from Wolfson MicroElectronics just announced Wolfson Pi Audio Card, a little board that gets me excited about its capabilities:


DIY and other audio enthusiasts might also like to build build stuff and play with it.

Why is this audio extension to the Raspberry Pi special?
As stated by Eddie, the main codec powering this board is WM own WM5102 Audio Hub.
http://www.wolfsonmicro.com/products/audio_hubs/WM5102/ plus what's necessary for SPDIF intput and output and more

WM5102 key features for me:
– 113dB SNR to Headphone out (DAC+amp)
– Headphone driver evolved from WM8994/WM1811 codecs as used in Voodoo Sound but with much lower hiss levels

The addition of SPDIF input means you can use it as standalone DAC.

But as it will be plugged on the Pi, it transforms it in a high quality 192kHz/24bit capable player on analog output with a lovely sounding headphone amp, gives it a standard SPDIF output without relying on HDMI, and also recorder for SPDIF and analog inputs.

I already have a head full of network audio rendering capabilities ^^
My first goal with this would probably be to:
– install pulseaudio on the Pi
– output everything from my computers here
– then plug my headphones here to finally have a DAC+Amp that sound good to drive my various headphones (especially the HD650) when I'm not using speakers.

Among other things 🙂

I'll see how it fares with some simple measurements and listening tests but I already expect higher sound quality than the typical over-hyped DACs+HP amp promising so much, being praised to no end and delivering so little in reality.
Also this WM5102 is present in Galaxy S4 I9500 but Samsung made several implementation errors preventing the phone to reach quality levels WolfosonMicro audio hub is capable of.
So this would also be a bit like a dev board to play with to no end and with very little limitations. Lovely!


I guess we'll need to wait a little bit to know more about price.

#supercurioBlog #audio

Community: Wolfson Pi Audio Card | element14
The Wolfson Pi Audio Card produced in partnership with Wolfson, the premier audio solutions chip company, offers Raspberry Pi users similar flexibility to a PC soundcard to capture audio alongside their camera, and experiment with stereo digital capture and playback.

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Yesterday I finally wrote my first display auto-calibration algorithm

Results are good 🙂
Also the approach is completely different from everything I saw so far.

Attached: D65 calibration on Nexus 7 (2013): very first results

I take all the measurements I need first and then everything can be done with calculations.
Usually auto calibration algorithms measure various kind of color patches that I can't justify, then try to improve their vastly interpolated early results by several optimization pass.
Not sure why they do that as it seems inefficient. Maybe those algorithms were designed with different goals in mind than mine.
Like if you're not sure of what the hardware will do with your profile, so you load it, retry, again and again.
But it means you're not measuring correctly to begin with or working with inconsistent and unpredictable hardware.

A huge benefit of my approach seems to be the accuracy first, and also you can tune the algorithm parameters all you want without taking any new measurement (which takes a vast amount of time).

Today I'm adding black point compensation strategies in it in order to provide a smooth gradation near black instead of clipping at rgb (10, 10, 15) on Nexus 7 (2013) when targeting a Gamma 2.2 response curve with pure black output.

And I'm having a lot of fun doing this!

I was really not sure I would be able to make this auto calibration thing, thinking I was too limited in my maths skills.
But it seems to be no issue even if it took quite some time to turn to code the theoretical concept I had in mind.

Back to code 🙂

#supercurioBlog #calibration #display #color #development


In Album Very first auto calibration algorithm results

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Alright I almost completed a brand new automated universal display measurement engine :)

The key here is that it's capable of measuring pretty much any kind of display: smartphone, tablet (any OS), TV, computer..
It also uses several techniques to give accurate results even on display implementing funky dynamic contrast, content adaptive backlight control or other similar effects.

During the process I learned a ton about color theory, maths, algorithms, colorspace conversion and representations.

..Which now gives me ideas on how to write my own automatic and high precision calibration engine!
Later maybe, but it's stuff I'm dreaming of since years actually.

Just letting you now that despite I didn't released new snapshots of the Android app, there's progress 🙂

#supercurioBlog #display #measurements #color

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Dear next person telling me "Movie Mode" on Samsung smartphones or tablets is color-accurate:

Please check your eye sight with a professional, and don't wait!

Here's the funky color response of Samsung Galaxy S 4 I9500 in Movie Mode.

#supercurioBlog #color #display #measurements


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Oh yeah, a win here!

Latest 2 or..3 days? and a bit more, I lost track of time I worked on something new, that among other things allows full-resolution measurements.

I never saw that before but I really wanted that for years so.. I did it 🙂
256 values per graph for grayscale.. can't do more accurate on a 24bit display!

This is a very good step towards a full calibration suite for mobile. I'll explain more about it later.

#supercurioBlog #display #measurements #color #development


In Album First full resolution measurements

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Look how well Firefox ICC profile color management works!

This test has been realized on Nexus 7 Original.
OG Nexus 7 (2012) display is quite under-saturated and generally dull.
Because of it's response curve (too bright) and also because of its weak gamut coverage: lacks in red, lacks even more in green.

In this example, I enabled Firefox Mobile color management support in about:config:
gfx.color_managmement.mode to 1
gfx.color_management.enablev4 to true
gfx.color_management.display_profile to /sdcard/og-nexus7.icc

Defining a color profile in software allows an application to alter the colors before they're sent to the lower levels and reach the display itself.
In the color-managed Firefox browser capture, you'll see that colors look over-saturated, especially Red and Green channels.
It's expected as applying the color profile compensate for the lacks of the display.
On the device itself, it looks just right and much nicer than anything the good old Original Nexus 7 is capable of usually.

A huge drawback today is that Firefox Mobile only renders content in 16-bit colors instead of 24, why you can see terrible banding in gradients.
Because of this, Firefox Mobile for Android is unusable for anything graphic related.
However, there's potential here.

Nightly built of the version 26 enables 24bit rendering!

It gives you and idea how color management, at OS or application level is useful, regardless of if you can actually calibrate the display hardware or not.

If the display is not calibrated, color management in software does all the work.
If the display is calibrated, color management in software will only compensate for hardware limitations of the hardware itself like typically the gamut size and coverage.

#supercurioBlog #color #colorManagement


In Album Color management and custom ICC profile in Firefox Mobile on Nexus 7 Original (2012)

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Do you know any color-managed Android web browser?

Just tested Chrome 29 and Firefox 23, and clearly they're not.

Here's a capture from Google Chrome Browser, the car should appear yellow.

Here's the test website: http://petapixel.com/2012/06/25/is-your-browser-color-managed/

Edit, another:

#supercurioBlog #color #colorManagement


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