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post #1 of 23 Old 04-02-2013, 02:21 PM - Thread Starter
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I have been trying to calibrate a friends Toshiba 40vr525rz LCD panel. The set has less than 1200 hours on it, he's owned it since new. I can get the RGB grayscale to track at dE of less than 1.5
from 10 to 100 IRE. The average gamma is 2.2, but has a slope going up from 10 to 90 at 2.0 to 2.4 and tracks poorly from 70 and up. The luminance chart looks pretty good. I've set the brightness so I can see a 1% window, and the contrast to the point where the RGB balance at 100IRE is just below a clip. The back light is set to put out 42fL.

The set has gains for red green and blue, and drives for green and blue only, so the gamma cannot be changed much from where the red tracks. There is no CMS, just a color and tint control. All enhancements are off. The gains are part of the service menu, and are available for the 3 preset color temps, cool, normal, and warm. There is not much else to adjust in the service menu.

The shadows on the picture when watching any content are red to a degree, most notably on faces. The only way I have found to remove this is to set the brightness so high the picture washes out badly. The backlight, and contrast controls have little to no effect on this. Moving the gamma control to a point where it measures 1.6 seems to get rid of most of the red. The dynamic contrast control will correct the shadows, but it makes a huge mess of the gamma, from 2.2 at 10 IRE to .96 at 90 IRE.

I'm using an i1d3 pro and an i1pro rev d, HCFR, and the AVCHD 709 disk played on a Panasonic blu-ray player.

Has anyone come across this problem, or this set in particular? Any ideas on how to minimize the discoloration in the shadows? The set is all my friend can afford at this time, and I would like to be able to make the best of what he has.





thanks in advance
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post #2 of 23 Old 04-02-2013, 02:57 PM
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I am going to guess here from what i have read about backlights. Not sure how low yours is set but if contrast is just below clipping at 100%, I assume you are going for high contrast rather than WTW head room
In doing this I assume you need to reduce the backlight to maintain 42fl.

Try setting contrast so you can see up to 253 and raise the backlight and readjust brightness if needed.
Check you gray scale and see if it doesn't need to be readjusted with a higher backlight but the same light output.
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post #3 of 23 Old 04-02-2013, 04:03 PM - Thread Starter
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I can set the contrast to 100 and still see all the way to 255. There is discoloration until the contrast is reduced to 70 or less. The clip in the red ends at a setting of 68. This is on a scale of 0 to 100 on the adjustments. The backlight is at 54 and gives 42 fL. At 60 51fL. The backlight on this set has next to no effect on the grayscale. Contrast and brightness have more of an effect, but not as much as I would have assumed. I've calibrated many sets, plasma, LCD, LED, CRT, and various projection technologies. I've only encountered this phenomena once before where it could not be corrected.

From where I have it set now, the only direction I can take the contrast is down, otherwise red will begin to clip, and quite quickly.I have had it as low as 45, and that improved the gamma marginally, the red in the shadows persists until the brightness is set so high the picture is washed out. A setting of 55 to 57 will show the 1% pattern without raising the MLL, Once the setting goes above 58, the picture begins to wash very quickly.

thanks for the reply Doug. Feel free to throw any other ideas my way. I feel I may learn something of value here, as this set does produce a very descent picture short of this anomaly.
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post #4 of 23 Old 04-02-2013, 04:53 PM
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Quote:
Originally Posted by vega509 View Post

I can set the contrast to 100 and still see all the way to 255. There is discoloration until the contrast is reduced to 70 or less. The clip in the red ends at a setting of 68. This is on a scale of 0 to 100 on the adjustments. The backlight is at 54 and gives 42 fL. At 60 51fL. The backlight on this set has next to no effect on the grayscale. Contrast and brightness have more of an effect, but not as much as I would have assumed. I've calibrated many sets, plasma, LCD, LED, CRT, and various projection technologies. I've only encountered this phenomena once before where it could not be corrected.

From where I have it set now, the only direction I can take the contrast is down, otherwise red will begin to clip, and quite quickly.I have had it as low as 45, and that improved the gamma marginally, the red in the shadows persists until the brightness is set so high the picture is washed out. A setting of 55 to 57 will show the 1% pattern without raising the MLL, Once the setting goes above 58, the picture begins to wash very quickly.

thanks for the reply Doug. Feel free to throw any other ideas my way. I feel I may learn something of value here, as this set does produce a very descent picture short of this anomaly.

I think the issue is grayscale tracking at very low levels of stimulus. Red might be overemphasized below 10% gray (maybe around 5% stim or even lower). Can you measure RGB tracking at lower levels then 10% gray? Also, does the grayscale ramp or steps pattern show discoloration at/near black? If you can see a red tint to grayscale patterns that are very dark (or any obvious discoloration), odds are there is a grayscale tracking problem at the very low end.

If that is not the case, I suppose it could be a gamut issue that could be exposed with luminance sweeps (dark reds are too bright/ruddy looking).

(I don't think it's the latter though.)

You say "the set has gains for red green and blue, and drives for green and blue only."

Does this mean the user grayscale controls are 1-pt (high end only) Green and Blue and also 1-pt (high end only) in the service menu for Red, Green, and Blue? Do you have any cuts/offsets/low end RGB controls?
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post #5 of 23 Old 04-02-2013, 05:28 PM - Thread Starter
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The 1% through 5% patterns show no color, nor does the 10% pattern. The ramp shows some color in the 60 to 80% range, slightly green.

The gain controls are in the service menu, the 2 drive controls are in the user menu. The drives work on the low end like you would expect cuts to. I have tried intentionally setting red 5% low at the lower IREs and still have reds in the shadows. I'll take a pic later and post it.
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post #6 of 23 Old 04-02-2013, 05:34 PM
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Originally Posted by vega509 View Post

The 1% through 5% patterns show no color, nor does the 10% pattern.

did you check this by eye?
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post #7 of 23 Old 04-02-2013, 07:12 PM - Thread Starter
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did you check this by eye?

both with the d3 and by eye.
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post #8 of 23 Old 04-03-2013, 01:19 PM - Thread Starter
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Here is a picture



this has the brightness set well above where the black patterns suggest, and high enough to still wash out the picture.
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post #9 of 23 Old 04-03-2013, 01:31 PM
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What does a 21 step gray scale ramp look like?
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post #10 of 23 Old 04-03-2013, 01:38 PM - Thread Starter
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Originally Posted by airscapes View Post

What does a 21 step gray scale ramp look like?

good, little to no color up to 65%, then a little of either of the 3 colors to 100%.

So far, the only way I've found to eliminate this is with the brightness control.
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post #11 of 23 Old 04-03-2013, 01:51 PM
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what happens if you turn down the color control a bit?

also, if you turn down color to zero, does the resulting B/W image still look discolored?
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post #12 of 23 Old 04-03-2013, 02:44 PM - Thread Starter
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the color control is set to 31 on a 1 to 100 scale. turning it down to 18 and the shadow becomes gray and remains right down to 0.



with color set back to 31, and the brightness set to 63, where 56 is the correct setting



this pic is inaccurate, my camera added some noise that is not there. The shadow area is actually rendered quite well with no discoloration. The brightness is now far too high as the image washes out badly.
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post #13 of 23 Old 04-04-2013, 11:27 AM
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so, it seems like a gamut or color decoding issue... not grayscale since B/W images are neutral gray

I'm not sure raising the black level is worth it, since an elevated MLL will always be detectable whereas as the discolored shadows only show up in dark scenes... if any controls should be manipulated to help minimize the issue, it would be color/tint (or possibly color space or color decoding presets, if they exist on this TV)
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post #14 of 23 Old 04-04-2013, 11:38 AM - Thread Starter
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Thanks for the replies. I find it strange that if a black and white film is viewed there is no discoloration in the shadows, much the same as when the color is set down to 0. A good example is the opening scene in Casino Royale.

PlasmaPZ80U you are likely correct that it is a color decoder issue. I do find it strange that on some movies like MIB it is far more prevalent than it is in Casino Royale in what would be equivalent dark scenes.
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post #15 of 23 Old 04-04-2013, 11:45 AM
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Quote:
Originally Posted by vega509 View Post

Thanks for the replies. I find it strange that if a black and white film is viewed there is no discoloration in the shadows, much the same as when the color is set down to 0. A good example is the opening scene in Casino Royale.

PlasmaPZ80U you are likely correct that it is a color decoder issue. I do find it strange that on some movies like MIB it is far more prevalent than it is in Casino Royale in what would be equivalent dark scenes.

it could be that the dark scenes in MIB are darker than the dark scenes in Casino Royale... probably has to do with whatever gamma number they chose when making the BD or DVD

also, in some movies the blacks are not true black, even in the darkest scenes (for example, when the black bars on the top and bottom of the screen appear darker than the blacks in the movie itself)
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post #16 of 23 Old 04-04-2013, 11:59 AM
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Just wanted to make sure.. you see this from all your input devices and from different movies from the same device correct? Sorry .. I just read back you do see it in other movies..
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post #17 of 23 Old 04-04-2013, 12:39 PM
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Something I didn't see mentioned and a possible root of the problem - often on LCDs, especially the less expensive ones, there is non defeatable color in the backlight (even if it is set to 0) which can be easily viewed with a grayscale step pattern. If that is the case, you're stuck with it. I've seen it many times measuring very low White luminance with my Klein K10-A.

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post #18 of 23 Old 04-04-2013, 12:46 PM
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Here it is:


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post #19 of 23 Old 04-04-2013, 12:50 PM - Thread Starter
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Quote:
Originally Posted by PlasmaPZ80U View Post

it could be that the dark scenes in MIB are darker than the dark scenes in Casino Royale... probably has to do with whatever gamma number they chose when making the BD or DVD

also, in some movies the blacks are not true black, even in the darkest scenes (for example, when the black bars on the top and bottom of the screen appear darker than the blacks in the movie itself)

I have noticed large differences from one movie to another in both the black level and the gamma levels. When I compared scenes between the 2 movies I did try to select scenes with the same overall brightness. The best I could do was to move the meter back from the set @ 30" and take some free measures and try to get as close as possible matching Y levels.

Quote:
Originally Posted by airscapes View Post

Just wanted to make sure.. you see this from all your input devices and from different movies from the same device correct? Sorry .. I just read back you do see it in other movies..

Back and white movies, or the opening scene in Casino Royal show none of this anomaly. It does show itself in most everything I've watched, but to varying degrees. Its almost non existent in the Underworld movies, Van Helsing, more prevalent in the Batman movies, and most noticeable in the MIB series. This I have not noticed on any of my sets, Plasma, LCD, and LED.

I just tried taking the cool color setting and calibrating it to D75, most of the shadow discoloring is gone. Taking cool to D65 and the shadows are colored once again. I've played across all 3 HDMI inputs, and now all 3 color temps. There are very large differences when selecting the color temp, even when they have all been adjusted for D65. The presets such as sports, cinema, etc all are horrendous, and cannot be adjusted. They all have dynamic contrast turned on which destroys gamma to get higher light output. For now, unless there is something I have overlooked, D75 is going to have to do. I doubt my friend would even see the difference, unless he has become used to the Plasma I loaned him while working on his set.

I guess I've been fortunate that with all the sets I've calibrated for friends and family, I've never had a set that had this anomaly, or as many bad traits as this one. It has definitely been a learning experience.

Thanks to all, and if you have any other thoughts please post them here, I'll have this set here until the weekend.
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post #20 of 23 Old 04-04-2013, 01:00 PM
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Quote:
Originally Posted by buzzard767 View Post

Something I didn't see mentioned and a possible root of the problem - often on LCDs, especially the less expensive ones, there is non defeatable color in the backlight (even if it is set to 0) which can be easily viewed with a grayscale step pattern. If that is the case, you're stuck with it. I've seen it many times measuring very low White luminance with my Klein K10-A.

are you referring to tinted blacks across the whole screen? or screen uniformity issues with respect to color specifically?
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post #21 of 23 Old 04-04-2013, 01:03 PM
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Have you checked for updated firmware?
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post #22 of 23 Old 04-04-2013, 01:24 PM
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Quote:
Originally Posted by PlasmaPZ80U View Post

are you referring to tinted blacks across the whole screen? or screen uniformity issues with respect to color specifically?

The backlight might show differences in the amount of color in different places just like clouding, flashlighting, etc,

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post #23 of 23 Old 04-04-2013, 01:39 PM - Thread Starter
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Quote:
Originally Posted by airscapes View Post

Have you checked for updated firmware?

just checked, it has the latest firmware.
Quote:
Originally Posted by buzzard767 View Post

The backlight might show differences in the amount of color in different places just like clouding, flashlighting, etc,

I quickly checked for uniformity issues when I began, by taking grayscale and gamut readings on all 4 corners and the middle of the set. The differences were very small. Surprisingly this set has no flashlighting I can see, Any grayscale patterns or gamut patterns show very good uniformity.
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