[Tips] Screen Color Calibration for the Galaxy Nexus

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mumchristmas

Member
May 9, 2011
12
53
0
After using the Galaxy Nexus for two weeks, I found the screen color of the new amoled+ is much better than the Nexus S, but still inaccuracy. I'm a part-time photographer who keen on the right Gamma, color accuracy and color temperature.

So I just finished some test with such things:
  1. Galaxy Nexus
  2. franco Kernel 18.5 nightly(with the ColorControl from Ezekeel)
  3. Voodoo Screen Test app
  4. x-rite i1 Display 2 color meter
  5. HCFR software

The test result was not so good...
  • Average Gammar value is about 1.9, far from the ISO stand 2.2. So the color is just too bright (I'm not saying screen brightness).
  • The shadow part (0-40% gray level) of 3 color curve were almost out of trim. In another words, incaauracy color balance.
  • As the color unbalance. The color temperature is starting from lower than 5500K to 6500K, which the ISO stand is 6500K at any color level.

I also tested the ColorControl in franco Kernel. After the adjustments, Gammar value is still bad, but I save the (most part of) color balance & color temperature in the end.

The adjustments step by step:
  • Make sure you have a rom/mod with /init.d autorun function.

    Bye, stock rom...:p

  • Make sure you have a kernel with ColorControl function.

    Such like Ezekeel, franco...Else? I don't know.

  • Set the screen brightness to 50%.

    It's the mesurement "baseline". But why 50%?
    Because, at this point the screen has a brightness about 120 Lux--also a ISO stand. So, it's very close to our desktop LCD.

  • Make a new file as /etc/init.d/900colorcontrol-b50

    Which could be done by Root Explorer or adb.

    Inside the file, type such line:
    Code:
    echo "-10 0 -10" > /sys/class/misc/colorcontrol/v1_offset
    
    echo "1820000000 1900000000 2000000000" > /sys/class/misc/colorcontrol/multiplier
    I choose "182 190 200" here, because the default value was about 200. Rising will increase the risk of LED Burn-in.

    And, don't forget the 7 zero!!!

  • Just reboot & enjoy the almost right color temperature.

    It's (6500±300)K at any color level in my device. Not perfect, but much better indeed.

Done, that's all I can do for you. :)
 
Last edited:

heo_con184

Senior Member
Oct 30, 2010
365
37
0
Montréal
Thanks so much for the mod.

I'm willing to test your new calibration for the GNex color but how can I revert back to stock in case of problem ?

So I guess we can only use this modification at 50% of brightness ? If we change to auto, how could it be ?
 
Last edited:

mohitrocks

Senior Member
Aug 15, 2010
829
581
0
Sorry for being a noob here, but this is compatible with any rom/kernel right? I'm currently running on AOKP Build 25 and Popcorn kernel 7.1

Thanks,
Mosh
 

mazubo

Senior Member
Jun 24, 2011
1,066
212
93
OnePlus 8
Hi, and thank you for offering your expertise. I'm not confident in doing the above.... Can you offer a little bit more step by step?

I've played around with root explorer which I imagine is what is necessary to change these values.you lost me at the 2nd step.....

Also, is 50% necessary?

Thanks kindly,



_______________________________
frAncO Kernel ;-P
 
Last edited by a moderator:

mumchristmas

Member
May 9, 2011
12
53
0
Hi, and thank you for offering your expertise. I'm not confident in doing the above.... Can you offer a little bit more step by step?

I've played around with root explorer which I imagine is what is necessary to change these values.you lost me at the 2nd step.....

Also, is 50% necessary?

Thanks kindly,



_______________________________
frAncO Kernel ;-P

Sorry for being a noob here, but this is compatible with any rom/kernel right? I'm currently running on AOKP Build 25 and Popcorn kernel 7.1

Thanks,
Mosh

Thanks so much for the mod.

I'm willing to test your new calibration for the GNex color but how can I revert back to stock in case of problem ?

So I guess we can only use this modification at 50% of brightness ? If we change to auto, how could it be ?

Step by step detail added. Thx for reading~
 
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fescen9

Member
Jun 24, 2008
46
1
0
You can change all of these settings from Franco's kernel updater program directly without modifying any files.
The OP's settings appear a little warm at first but I'm liking them so far...

Sent from my Galaxy Nexus using xda premium
 

dmmarck

Senior Member
Apr 11, 2011
467
78
0
Instead of making that script, can we just input those numbers into the Color Control?

-10, 0, -10 for Gamma (RGB);
182, 190, 200 for Multiplier (RGB)

Right?
 
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phunghoang24

Senior Member
Apr 18, 2010
291
7
0
Thank!
your feeling about color is exactly. Gray is dirty, it's not sync at all pixels.
I hope someone changes this by kernel - easy for me control everything :(
After flash franco kernel it's better more but not perfect.
If this problem is not improved, i'll buy other phone that uses Superamoled PLUS replace this one . HIZzzz
 
Last edited:
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dario3040

Senior Member
Feb 9, 2010
1,737
152
0
Oslo
Thank!
your feeling about color is exactly. Gray is dirty, it's not sync at all pixels.
I hope someone changes this by kernel - easy for me control everything :(
After flash franco kernel it's better more but not perfect.
If this problem is not improved, i'll buy other phone that uses Superamoled PLUS replace this one . HIZzzz

And that would do absolutely nothing :)
SAMOLED Plus displays are identical to the SAMOLED HD displays when it comes to colors and such.
 

solarus2011

Senior Member
Jan 9, 2011
945
994
0
Atlanta, GA
Thanks for the info. I had mine looking very similar but with a combination of lower brightness and higher multiplier values. Nice to have it set now without the additional risk of burn in. Thanks a ton.
 

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  • 50
    After using the Galaxy Nexus for two weeks, I found the screen color of the new amoled+ is much better than the Nexus S, but still inaccuracy. I'm a part-time photographer who keen on the right Gamma, color accuracy and color temperature.

    So I just finished some test with such things:
    1. Galaxy Nexus
    2. franco Kernel 18.5 nightly(with the ColorControl from Ezekeel)
    3. Voodoo Screen Test app
    4. x-rite i1 Display 2 color meter
    5. HCFR software

    The test result was not so good...
    • Average Gammar value is about 1.9, far from the ISO stand 2.2. So the color is just too bright (I'm not saying screen brightness).
    • The shadow part (0-40% gray level) of 3 color curve were almost out of trim. In another words, incaauracy color balance.
    • As the color unbalance. The color temperature is starting from lower than 5500K to 6500K, which the ISO stand is 6500K at any color level.

    I also tested the ColorControl in franco Kernel. After the adjustments, Gammar value is still bad, but I save the (most part of) color balance & color temperature in the end.

    The adjustments step by step:
    • Make sure you have a rom/mod with /init.d autorun function.

      Bye, stock rom...:p

    • Make sure you have a kernel with ColorControl function.

      Such like Ezekeel, franco...Else? I don't know.

    • Set the screen brightness to 50%.

      It's the mesurement "baseline". But why 50%?
      Because, at this point the screen has a brightness about 120 Lux--also a ISO stand. So, it's very close to our desktop LCD.

    • Make a new file as /etc/init.d/900colorcontrol-b50

      Which could be done by Root Explorer or adb.

      Inside the file, type such line:
      Code:
      echo "-10 0 -10" > /sys/class/misc/colorcontrol/v1_offset
      
      echo "1820000000 1900000000 2000000000" > /sys/class/misc/colorcontrol/multiplier
      I choose "182 190 200" here, because the default value was about 200. Rising will increase the risk of LED Burn-in.

      And, don't forget the 7 zero!!!

    • Just reboot & enjoy the almost right color temperature.

      It's (6500±300)K at any color level in my device. Not perfect, but much better indeed.

    Done, that's all I can do for you. :)
    10
    can someone help me out?
    Yes i can :)

    1. Connect your phone to PC
    2. Download and extract attached .rar file
    3. Open extracted folder and double click on "FixNexusGamma.bat".

    PS. make sure you have enabled "USB Debugging" (go to Settings->Developer options to double check).

    PSS. This and OP's guide won't work on ROM's that has no init.d script autorun function!
    8
    There's been a lot of bad suggestions by people in this thread in terms of "accurate" colors. If you just want to calibrate your device to what looks good to you, that's great. But accurate colors are something completely different.

    I spent a few hours messing around with HCFR and my Xrite i1d2 meter and came up with quite an accurate calibration. You can actually absolutely nail the colors on this screen - they are visually indistinguishable from perfect reference. The only thing I haven't figured out yet is gamma. It totally sucks no matter what I do - I can't get a flat gamma curve.

    Anyway, here's what I came up with using the Franco Kernel app:

    Absolutely perfect greyscale:

    galaxynexuscolors.jpg


    Pretty much bang on color temp

    galaxynexuscolortemp.jpg


    Once again, quite good

    galaxynexusprimaries.jpg


    And then gamma sucking the big one:

    galaxynexusgamma.jpg


    Despite the gamma, the screen looks a billion times better than before. But the gamma is quite frustrating for watching videos. It's better than stock, but pretty far off.

    Here were my settings:

    50% brightness

    Color Multipliers:

    Red: 190
    Green: 150
    Blue: 180

    Gamma:

    Red: 8
    Green: 0
    Blue: 8

    OMAP Gamma: 1.2

    Some things I noticed:

    The three gamma controls affect the low end more than the high. So for example, an adjustment of - or + 1 gamma was a big deal at IRE 30, but not much at IRE 80. The color multipliers were the opposite - they affected IRE 60-90 hugely, but not much down low. I almost used the multiplier and gammas like the classic gain and bias calibration controls on consumer electronics.

    Also, color multipliers over 200 DONT DO ANYTHING . You can jack it up to 350 if you want, but it won't budge even 1% on the meter. The best way to calibrate this screen is to pick your weakest color, and cut down the other two channels to match it.

    Unfortunately, what works for me may not work for you as all screens are different. But for my particular device (day 1 preorder, first revision) this is easily, easily, easily the best calibrated cell phone display I've ever seen.
    7
    So I started playing around with the color settings using Franco's Kernel and app. The settings I am using make the screen look amazing and the whites really pop.

    It looks like a totally new screen. When I went back to stock to compare, I could not believe how bad and washed out the screen looked. Curious what others think of these settings....

    In Franco App:
    Color Multilpliers
    Red = 180
    Green = 192
    Blue = 235

    Red / Green / Blue
    -10 / 0 / 10

    OMAP4 Gamma Interface
    1.4
    3
    I'm sorry, but this is not entirely right.
    Your recommended settings are correct for srgb as rgb working space - srgb however has a relatively low gamut compared to adobergb and ecirgbv2. Also, srgb should only be used by web designers, as it is also the native mode of every computer display. Photographers should use adobergb (native dslr color space) or ecirgbv2 (f.e. prepress retouching).

    here are the official calibration targets for each color space:

    srgb
    Gamma 2.2
    Color temp 6500k
    Whitepoint 140cd

    AdobeRGB
    Gamma 2.2
    Color temp 6500k
    Whitepoint 120cd

    eciRGBv2:
    Gamma L*
    Color Temp 5000k
    Whitepoint 120cd

    None of these settings are good for practical use tho (in prepress at least).
    For best color accuracy, I recommend a color temp around 5700-5800k, 140cd and L* or 2.2 gamma, depending on your rgb working space (adobe or ecirgbv2).

    photographers should use ecirgbv2 or adobergb, depending on what kind of work he or she does. ecirgbv2 is best suited for prepress use, as it offers the best color conversions to ISOCoatedv2.

    General note:
    whitepoint should always be adjusted to look like a white sheet of paper of your favorite photo paper.
    color temp should always match the grade of white of your fav photo paper (bleached paper f.e. has a higher white point as yellow natural paper)

    hth
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