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

[Metallice]

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.

 

[Metallice]

I may use this for other sysfs tweaks... mine for now.

 

[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

 

[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!

 

[Metallice]

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

 

[Metallice]

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

 

[archie88]

This is awesome. It definitely needs to be implemented in a ton of ROMs

 

[jarjar124]

so does flashing this decrease battery life when watching videos? im confused by op..

 

[hamdir]

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

 

[phanboy4]

Nice find. Hopefully Google/Nvidia/Asus will fix this in an update.

 

[jtrosky]

Thank you very much for this! While I don't own a Nexus 7, I *do* own an Asus TF700T and this problem also exists on it. On the TF700, this "mode" is active all of the time, no matter what you are doing and it is *very* noticeable and distracting, especially when watching videos (but it *is* noticeable everywhere else as well).

Disabling this "Feature" makes the problem go away. At the very least, you can enable/disable as needed now.

Thanks again!

Sent from my ASUS Transformer Pad TF700T using Tapatalk 2

 

[Riquelme10]

Hello from Germany,

my Nexus is unlocked and rooted

Terminal:

su
cd /sys/devices/tegradc.0/smartdimmer
./enable

"Permission denied"

change user rights:

chmod 744 enable
(old settings are 644)
./enable

./enable[1]: 1: not found


so where is my fault?

 

[hamdir]

ever since i disabled this gamma destroying feature and my screen keeps getting better and better

starting to fall in love with it really

 

[sharp2G]

Hello from Germany,

my Nexus is unlocked and rooted

Terminal:

su
cd /sys/devices/tegradc.0/smartdimmer
./enable

"Permission denied"

change user rights:

chmod 744 enable
(old settings are 644)
./enable

./enable[1]: 1: not found


so where is my fault?

you didn't even enter the command line properly...

Sent from my Nexus 7

 

[espionage724]

you didn't even enter the command line properly...

Sent from my Nexus 7

Care to post how it should be done then? Might be a little bit more helpful

Also, does this affect battery life overall? Or just while watching movies?

 

[jtrosky]

Hello from Germany,

my Nexus is unlocked and rooted

Terminal:

su
cd /sys/devices/tegradc.0/smartdimmer
./enable

"Permission denied"

change user rights:

chmod 744 enable
(old settings are 644)
./enable

./enable[1]: 1: not found


so where is my fault?

You do not "run" the "enable" file. You need to do this:

echo "0" > /sys/devices/tegradc.0/smartdimmer/enable
or
echo "0" > enable (if you are already in that dir).

That will disable the SMartDimmer "feature". Echoing a "1" will re-enable it. I have not noticed any battery life difference....

Sent from my ASUS Transformer Pad TF700T using Tapatalk 2

 

[hamdir]

Care to post how it should be done then? Might be a little bit more helpful

Also, does this affect battery life overall? Or just while watching movies?

yes its an LCD battery saving feature and so disabling it will definitely reduce battery life

choose between battery life or quality display

 

[Metallice]

yes its an LCD battery saving feature and so disabling it will definitely reduce battery life

choose between battery life or quality display

Yes as said in the OP smart dimmer analyzes the video frames and determines whether it can lower the backlight while increasing the color brightness and maintain almost the same image. Lower backlight = better battery life.

Sent from my Nexus 7 using xda premium

 

[Ravynmagi]

After I turned off the dimmer, the screen got a little brighter, so I manually turned down my normal 40% brightness to 30% brightness. So in the end I don't think I'm losing any battery life at all.

 

[jtrosky]

After I turned off the dimmer, the screen got a little brighter, so I manually turned down my normal 40% brightness to 30% brightness. So in the end I don't think I'm losing any battery life at all.

I agree - I think any battery life reduction will be *very* minor for most people... I certainly haven't noticed any difference...

Sent from my ASUS Transformer Pad TF700T using Tapatalk 2