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[GUIDE][FIX] Nvidia PRISM/smartdimmer - fix screen washout after watching videos

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By Metallice, Recognized Contributor on 4th August 2012, 11:53 PM
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THE PROBLEM

To save battery while playing video Tegra intelligently decreases the backlight while increasing color brightness and contrast. Because it monitors on a frame by frame basis the changes are often unnoticable. You basically end up with the same displayed image using less backlight.

Unfortunately it seems to get stuck even after you leave the video and the changes are very noticeable as the changes were specific to the video frame you just left and not your homescreen.

This also may be the cause of some ghosting issues and for some it seems to eliminate any ghosting problems for them.

MANUAL FIX
(will reset at each reboot)

In terminal -
(You may need to type "su" and press enter before entering these commands)

To turn it off

echo "0" > /sys/devices/tegradc.0/smartdimmer/enable

To change how aggressive it is (untested)

echo "#" > /sys/devices/tegradc.0/smartdimmer/aggressiveness

Note: battery life while watching videos WILL decrease if you turn it off or decrease the aggresiveness

AUTOMATIC FIX

Trickster Mod
- has the ability to disable PRISM and set it to disable on boot.

N7scripts.rar
- A collection of scripts compiled by hamdir which, in conjunction with Script Manager (available in the market) will allow you to toggle smartdimmer/PRISM on and off at will.
- You can also use script manager to toggle it at boot if you want.
- Also includes a script to disable 3D scaling which may improve 3D gaming performance (untested)

Thanks to hamdir for his pack of scripts and for convincing me to make a new post for these fixes.
Attached Files
File Type: rar N7scripts.rar - [Click for QR Code] (435 Bytes, 2230 views)
File Type: rar N7scripts.rar - [Click for QR Code] (435 Bytes, 2230 views)
Last edited by Metallice; 7th October 2012 at 06:42 PM.
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4th August 2012, 11:54 PM |#2  
Metallice's Avatar
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I may use this for other sysfs tweaks... mine for now.
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5th August 2012, 01:08 AM |#3  
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Thanks. Easier to save and flash then manually entering in these values each time I crackflash.

If the T3 can increase the color saturation and gamma while decreasing backlight, wonder if we can increase the colors while leaving the backlight alone. All of the N7s I've played with have a dull washed out look with a warm tone for whites.

Sent from my Nexus 7 using xda premium
Last edited by player911; 5th August 2012 at 01:11 AM.
5th August 2012, 02:01 AM |#4  
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does flashing the .zip just delete the PRISM file? cuz when I manually enter the command after flashing it via CWM it doesn't allow me to any more.

"
ROM may flash stock recovery on boot? Fix?

No
.
.
.
.
.
Yes - Disable Recovery flash
.
.
.
+++ Go back +++

which reboots if you "go back" what is this?


-------------------------------------------------------------------------

How do you set up the script? I have script manager and the Scrip.rar saved onto my SD card. Thanks in advance!
Last edited by sharp2G; 5th August 2012 at 02:24 AM.
5th August 2012, 02:53 AM |#5  
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Quote:
Originally Posted by player911

Thanks. Easier to save and flash then manually entering in these values each time I crackflash.

If the T3 can increase the color saturation and gamma while decreasing backlight, wonder if we can increase the colors while leaving the backlight alone. All of the N7s I've played with have a dull washed out look with a warm tone for whites.

Sent from my Nexus 7 using xda premium

Messing with the kernel I haven't had any luck. You could ask Morfic. He might be able to make something happen.

Also prism increase color BRIGHTNESS for the most part (you said saturation). That's why the homescreen ends up looking washed out and bright and not oversaturated when PRISM fails to shut off.

Sent from my Nexus 7 using xda premium
5th August 2012, 02:58 AM |#6  
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Quote:
Originally Posted by sharp2G

does flashing the .zip just delete the PRISM file? cuz when I manually enter the command after flashing it via CWM it doesn't allow me to any more.

"
ROM may flash stock recovery on boot? Fix?

No
.
.
.
.
.
Yes - Disable Recovery flash
.
.
.
+++ Go back +++

which reboots if you "go back" what is this?


-------------------------------------------------------------------------

How do you set up the script? I have script manager and the Scrip.rar saved onto my SD card. Thanks in advance!

There's no prism file. These tweaks are changing a sysfs value. There's no file. The flashable zip adds an init.d file that runs the manual command at every boot.

In your case CWM is complaining about a file that flashes stock recovery on boot and overwrites CWM. These are completely different things. Let CWM "disable recovery flash" and you'll be good to go.

Sent from my Nexus 7 using xda premium
5th August 2012, 04:24 AM |#7  
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This is awesome. It definitely needs to be implemented in a ton of ROMs
5th August 2012, 04:33 AM |#8  
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so does flashing this decrease battery life when watching videos? im confused by op..
5th August 2012, 11:33 AM |#9  
hamdir's Avatar
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awesome post, thx!

yes this fix, completely get rid of the grey levels washout issues!!! and greatly improves the quality of the display, it will cost some battery life, but any boost to this average screen is welcome

now about ghosting it did reduce it a lot but sadly it didn't kill it, i still get the very random occasion of faint LCD ghosting

finally we really need to find out a way to fix the stupid low saturation, in particularly the greens are very low

google....these screen issues, lack of tablet UI and launcher rotation issues, makes want to smash it through the wall
Last edited by hamdir; 5th August 2012 at 11:36 AM.
5th August 2012, 02:01 PM |#10  
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Nice find. Hopefully Google/Nvidia/Asus will fix this in an update.
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