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Gamma setting (Grey screen)

One more thing

Active Member
Quick question to the colour pros out there,
Whilst projecting onto a grey BW painted wall, I have had to change the gamma down (or up?) to 1.8, to reveal all the shadow detail, the blacks were getting severely crushed at 2.2-2.4. Is this normal for a grey screen or could it just be the PJ i'm using (Benq1400)?
 

Peter Parker

Distinguished Member
I doubt it's anything to do with the screen as it's a passive device. Shadow detail visibility and the Gamma you use will be affected by the available on/off contrast of the projector, and the surroundings. In a dark decor room with no ambient, you can use a higher gamma, but the on/off contrast will limit how high you can go. 1.8 doesn't sound far wrong for something that probably has only around 2000 to 3000:1 genuine on/off contrast. An entry to mid level JVC can go to around 2.2 without crushing unless you make a custom gamma.

Have you set up the brightness and contrast using a test disk? That can also make a difference to what you see, but it shouldn't affect the gamma. Have a look at my link for basic calibration, and specifically the avforums videos. They will show you how to set the levels and the effect it has on the image. Then try the gamma again. Also, check both HDMI settings to make sure you're using the correct one, because that can cause issues there too.

Gary
 

One more thing

Active Member
I doubt it's anything to do with the screen as it's a passive device. Shadow detail visibility and the Gamma you use will be affected by the available on/off contrast of the projector, and the surroundings. In a dark decor room with no ambient, you can use a higher gamma, but the on/off contrast will limit how high you can go. 1.8 doesn't sound far wrong for something that probably has only around 2000 to 3000:1 genuine on/off contrast. An entry to mid level JVC can go to around 2.2 without crushing unless you make a custom gamma.

Have you set up the brightness and contrast using a test disk? That can also make a difference to what you see, but it shouldn't affect the gamma. Have a look at my link for basic calibration, and specifically the avforums videos. They will show you how to set the levels and the effect it has on the image. Then try the gamma again. Also, check both HDMI settings to make sure you're using the correct one, because that can cause issues there too.

Gary
Thanks Gary,

Yeah it's in a living room so not the best for contrast anyway.

I couldn't find a link for the basic calibration, is it a disk? Will try that out though. Thanks for your input it's all a learning curve!

Chris
 

mojogoes

Remembered (1961-2016)
Remember when calibrating to calibrate your pj in the very same lighting conditions that you usually view under as to some degree it won't mean a thing especially when it come to the basic brightness and contrast settings.
 

One more thing

Active Member
Many thanks to all for all that. I run all my media from a mac mini htpc so would need a download, I tried to download the AVS 709 mp4 one but it seems the link is broken or missing. Is there any other downloadable calibration test out there that runs on a mac?

Cheers
 

One more thing

Active Member
Hi mate,

Trouble is I don't use bd player or any optical disk just play from plex on Mac mini, do you know if there are any download equivalents?
 

Peter Parker

Distinguished Member
What I used to do was rip the disk to my HTPC and then run it in my software player. Can you do that?

I always used video levels (16 to 235) rather than expanded.

Gary
 

One more thing

Active Member
Being apple though they dropped the optical drive on mac minis a while back! Am surprised I cannot get an Mkv or similar download of the same?
 

Peter Parker

Distinguished Member
There might be something - if you go to the forum the download is linked from (avsforum), you can ask there. Can you use an external drive?

Gary
 

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