# Are all Grey Scale images the same?



## carlscan26 (Apr 17, 2012)

Hello all,

The power supply on my Samsung Plasma (PN50B850Y1F) was replaced so I pulled out my calibration tools. I have two sets of calibration discs: the DVE Basics BR and I recently added the AVCHD 1.3 disc. I have the latest V4 version of Calman and a Chroma 5 meter.

Out of curiosity I ran the grey scale measurements using each disc's grey scale images and recorded the following results:

This is the GS with the DVE Basics images:









And here are the results with the AVCHD images:









I did not make any adjustments to the display between these two sets of readings. I didn't expect them to be exactly the same but I didn't expect to see opposite curves for the gamma as you can see from 80-100% The differences stayed consistent as I retested after color gamut adjustments too. 

Are these differences normal?


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## mechman (Feb 8, 2007)

Go pad 5 posts here and retry the attachments. You can't do certain things here until you have 5 posts. And sometimes it may take an hour or so for you privileges to be given after the 5th post.


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## carlscan26 (Apr 17, 2012)

mechman said:


> Go pad 5 posts here and retry the attachments. You can't do certain things here until you have 5 posts. And sometimes it may take an hour or so for you privileges to be given after the 5th post.


Ok I just got to 5 - this should be #6. I think I followed the directions about posting images correctly. So I'll wait a few hours and hopefully I did do it correctly.


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## carlscan26 (Apr 17, 2012)

mechman said:


> Go pad 5 posts here and retry the attachments. You can't do certain things here until you have 5 posts. And sometimes it may take an hour or so for you privileges to be given after the 5th post.


I followed the directions on this thread (http://www.hometheatershack.com/for...-attachments-system-prior-having-5-posts.html) to upload the images above - so do those directions not work if you don't have 5 posts?

Going forward should I still use this method for postig images or is there a better/preferred method to use?

Thanks in advance


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## Joel Barsotti (Nov 26, 2011)

The big difference is window size.

The size of the pattern on a plasma can make a big difference in how they measure. You really want the smallest size available to get the most consistent response.


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## tonyvdb (Sep 5, 2007)

Upload your images here its fairly straight forward and then link to those images in this thread.


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## carlscan26 (Apr 17, 2012)

I've re-done the link to the images. I'll have to queue up the discs but I believe the DVE fields are bigger and they also have the pluge bars displayed too.

I'd appreciate some thoughts on the differences between these readings, the opposite gamma points at the high end really surprised me.


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## carlscan26 (Apr 17, 2012)

The DVE results:










and the AVSHD:


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## mechman (Feb 8, 2007)

I'll check these disks today. I have both of them and I'll see if I'm getting the same results.

What meter are you using?


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## carlscan26 (Apr 17, 2012)

mechman said:


> I'll check these disks today. I have both of them and I'll see if I'm getting the same results.
> 
> What meter are you using?


That would be great; I wasn't able to run them last night and I'll be traveling for a few days.

I have a Chroma 5 meter, running the latest version of CalMan v4 (Version 4.6.0, Build 368)


Thanks again!


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## Joel Barsotti (Nov 26, 2011)

carlscan26 said:


> That would be great; I wasn't able to run them last night and I'll be traveling for a few days.
> 
> I have a Chroma 5 meter, running the latest version of CalMan v4 (Version 4.6.0, Build 368)
> 
> ...


I'm nearly certain the issue is with the different window sizes. The discs have been verified to have the same levels. What you can see it that 100% of white has a bit different Y values, I don't have the discs infront of me, but I'd guess the AVS disc has smaller windows and therefore has higher Y values.

Plasmas are very sensitive for gamma, but if you notice the RGB tracking is good on both of them.


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## mechman (Feb 8, 2007)

I will get the screen grabs later but there was very little difference (something like .001) difference between the 2 discs on my Sony LED/LCD. I intended to check this on one of my plasmas but I do not have a blu-ray player hooked up to either of them. :huh:

I would take Joel's word for it that it is more than likely the different window size. Plasmas are sensitive to this. Plus Joel knows what he's talking about. :T


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## mechman (Feb 8, 2007)

Here are my measures using my Chroma 5.

DVE HD Basics










avs Disk measures










Looks like the largest difference is at 20% - .0007.


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## carlscan26 (Apr 17, 2012)

Thanks Mechman! Those tracked are even better than I expected.

I am definitely taking Joel's word as gold :T 

Do you enable the low light handling with your Chroma 5? If so do you use the default settings?


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## carlscan26 (Apr 17, 2012)

Joel Barsotti said:


> I'm nearly certain the issue is with the different window sizes. The discs have been verified to have the same levels. What you can see it that 100% of white has a bit different Y values, I don't have the discs infront of me, but I'd guess the AVS disc has smaller windows and therefore has higher Y values.
> 
> Plasmas are very sensitive for gamma, but if you notice the RGB tracking is good on both of them.


Thanke Joel! So do you recommend calibrating with the smaller pattern then? If this creates a conflict with a vendor/partner, then please ignore my question.


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## Joel Barsotti (Nov 26, 2011)

carlscan26 said:


> Thanke Joel! So do you recommend calibrating with the smaller pattern then? If this creates a conflict with a vendor/partner, then please ignore my question.


Yes we recommend using the smallest patterns available for plasmas.


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## mechman (Feb 8, 2007)

carlscan26 said:


> Thanks Mechman! Those tracked are even better than I expected.
> 
> I am definitely taking Joel's word as gold :T
> 
> Do you enable the low light handling with your Chroma 5? If so do you use the default settings?


You know I never even looked at the settings to see if it was enabled. :scratch: I usually just use it at the default settings unless something doesn't seem right.


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## carlscan26 (Apr 17, 2012)

I spoke with Spectracal tech support and found out its not needed for the Chroma 5. Sounds like the readings may be a hair more stable with it on but the meter has excellent low light sensitivity.


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## carlscan26 (Apr 17, 2012)

Joel Barsotti said:


> I'm nearly certain the issue is with the different window sizes. The discs have been verified to have the same levels. What you can see it that 100% of white has a bit different Y values, I don't have the discs in front of me, but I'd guess the AVS disc has smaller windows and therefore has higher Y values.
> 
> Plasmas are very sensitive for gamma, but if you notice the RGB tracking is good on both of them.


OK so I measured the fields last night, and on my 50" plasma the fields measured in at:

AVSHD: 15"X9.5"
DVE: 16"X10"

The DVE also has the pluge bars to the sides of the fields, so the AVS disc definitely has less on the screen.


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