HDTV Calibration Sweep Method DIY

Greetings,

This is a method I discovered by accidentally adjusting contrast and brightness and seeing that these parameters have an effect on rgb levels during continuous measurements. Instead of focussing primarily on rgb levels at each window ire interval, I concentrated on what would be the best contrast and brightness level for my hdtv that would allow rgb levels close to 100 % from 30 ire to 80 ire. The reason that I call it the sweep method is simply sweeping or raising/lowering the contrast or brightness levels to produce consistent rgb levels across the grayscale.

I just calibrated my Samsung PN50b450 by using hcfr software and xrite eyeone lite and gamma response is pretty level. I have been DIY calibrating for over two years. Recently, I initially started using the HD DVE disc with the red/green/blue levels even at 100% at 80 ire. I then noticed the other rgb levels at 50, 60, and 70 were not level but were greatly affected when adjusting the contrast and brightness levels. I kept adjusting the rgb levels at from 50 to 80 ire by using the contrast/brightness controls (and also readjusting the rgb gain and offset levels if necessary to tweak the levels for consistency), and later separately rgb levels from 30 to 40 ire, until all rgb levels of the greyscale from 30 to 80 consistently came within 2 percent of 100% levels. This made my gamma a straight flat line and a terrific picture. My highest delta E is 2.5.

I think that all hdtv's have a sweet spot which can be found by adjusting (slowly but surely) the contrast and brightness settings to where rgb levels are consistent between 30 and 80 ire. For example, if your 70 ire has a red level at 95%, adjusting the constrast or brightness may raise this level while not affecting the 80 ire rgb levels. After I completed my adjustments, my 100 ire had a measurement of 40.8 ftL and the 10 ire was exactly .65% of the 100 ire, which may be perfect.

I call this the "sweep" method and it primarily involved adjusting the contrast and brightness levels and a lot of trial and error. See the images below for the gamma and rgb graphs.

Suggestions and protocols imho:
1. measure each window pattern while adjusting contrast or brightness in continuous measurement mode (green arrow). if using DVE patterns (not for avs) turn off continuous measurements when changing window patterns. also readjust rgb gains and offsets if necessary and for greyscale consistency when changing to a different contrast or brightness level.
2. make sure sensor is in middle of window pattern to avoid light impact on measurements from edges
3. light from on screen controls used while making adjustments may impact measurements. may need to turn off controls while in continuous measurements to get true measurement
4. plasma displays such as mine may need to warm up as much as 1 hour or more to obtain true color measurements
5. recalibrate sensor every 20 minutes or just prior to final greyscale measurement
6. turn off sharpness settings on your dvd or blu ray player when setting sharpness for your hdtv
7. follow Curt Palme's calibration for dummies religiously

The cell light was originally set at 10 - as recommended for this display, but readjusted to 9 to level out a bump in the gamma graph. I also attempted to lower the cell to 8 but the gamma graph just went bonkers.

The following are my settings for a dark room setting. The resulting gamma was 2.36 (the hcfr gamma setting preference for 2.4 for dark room environment), with static contrast at 1173:

movie mode
cell 9
contrast 87
brightness 53
sharpness 29
color 47
tint 50
gamma 0
color space auto
Grayscale:
offset: red 29, green 25, blue 35
gain: red 25, green 25, blue 45
mode warm2
16:9
hdmi black level low
all options off

Good Luck,

Vincentfam

Attachment 218751

Attachment 218752

Greetings again:

Below are other calibration settings I obtained using the above method for component cable connection for my samsung plasma hdtv. I have also attached the gamma graph which shows a very flat gamma curve.

One reason why the gamma curve may be flatter for 80 through 100 ire is because I used the small apl patterns instead of the window calibration patterns to avoid the automatic brightness limiter (abl) that is usually found on plasma tvs.

100% ire was measured at 50+ ftL, but this was probably high due to the use of small apl patterns.

Color readjusted back to 48
component cable, using apl small windiows

cell 9
contrast 89
brightness 53
sharpness 42 (used dve disc for sharpness with 720p pattern)
color 48
gamma 0
color space auto
offset red 35, green 25, blue 36
gain red 30, green 25, blue 44
mode warm2
16:9
hdmi black level low
all options off

As always,

Vincentfam



Attachment 219670

Attachment 219671

Greetings finally,

I am posting the following "quote" from another discussion in this forum to further illustrate the calibration sweep method:


In doing calibrations for my samsung, I used windows and small apl patterns. The apl's were used to avoid the automatic brightness limiter (abl) effects on my plasma. A recent calibration disclosed the effects of abl when my measurements @ 80 ire windows for blue and red suddenly dropped from 100% to 95% and there was nothing I could do raise them back to 100%, other than time and allowing the hdtv to readjust itself. Apparently, the tv was designed to have abl for its energy saver feature.

Final analysis: I am opting to use [Preference for using apl patterns deleted. Felt that post calibration using apl patterns may not produce realistic calibration. Picture appeared off. Went back to using regular window patterns for a calibration that provides a "real" response].

Forum Hint: "abl" is probably affecting your plasma tv calibration if your 100% ire ftL luminance (Y) reading for a small apl pattern is higher than a 100% ire ftl luminance (Y) reading for a regular windows pattern.

Nonetheless, sharpness is very important as well. Here is another quote that may be useful:


Edit Note: Sharpness adjustment - I check my hdtv's service manual that stated that a "720p" signal be used when calibrating. I previously used 1080i settings for calibration. I then calibrated sharpness using the DVE on my blu ray in 720p setting with a 720p sharpness pattern, which made a significant difference. Also, a recheck of rgb levels and the gamma curve revealed no changes.
Finally [Oct 3, 2011], I believe that this is a good calibration method, especially if your hdtv does not have the necessary picture controls like cuts or offsets, like my wife's Toshiba 37AV502, which doesn't have the cuts or bias controls in the service menu. Changing contrast and brightness impacts rgb in the 0 to 50% ire windows, much like bias, cuts, or offset controls.
Good luck,

As I remain, Vincentfam.

tedmales,

You may want to check out my updated settings in the plasma display forum at this link: http://www.avsforum.com/avs-vb/showp...postcount=1235

I used the "ganging" method by equally increasing/decreasing the rgb gains and offsets, where necessary, and decreased the gamma setting in the advance settings to get an average gamma level between 2.4 and 2.5, which is recommended by some forum regulars. Also, later in that link above, I set the black tone to darkest and adjusted contrast to obtain proper brightness level to increase the static contrast ratio, with some adjustment to color and tint. Also used pop sharpness technique to get a pop from the picture. The thread is Samsung PN**B450 Picture Settings in the plasma display area. Picture looks great.

Good luck,

Vincentfam

thebox,

For your basic ganging technique, per this forum, evenly raising rgb gain levels will lower gamma level from 50 - 100 % gray, and vise versa. raising rgb cut or offsets will impact gamma level from 0 - 50 % gray. Lowering the rgb levels will of course raise the gamma levels. Please note that cell light settings also impact gamma levels.

You want to get a brightness level and contrast (picture) level where the contrast is at its highest possible setting that does not produce color at 100 % ire. For my samsung, anything over a contrast setting of 89 introduces a red tint.

Let me know how it turns out.

Vincentfam