Calibration issues (clipping) - AVS Forum
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post #1 of 2 Old 01-06-2013, 11:53 AM - Thread Starter
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Has anyone done tests to verify Mac can output full 16-235 levels? And full 0-255 levels? I can't get full 16-235 and nothing from WTW and BTB. I don't think the problem is my TV.

Connecting my Macbook Air (2012, Mountain Lion) via Thunderbolt port to Samsung LED TV (UN50EH6000) using Thunderbolt-to-HDMI cable (Monoprice) shows lots of white clipping. A check in system preference/display/color shows the display profile used is called "HD 709-A". This was chosen for me when I plugged the mac into the Samsung.

Using AVSHD709 test patterns, the white clipping pattern shows no white flashing at all, including all the ones below reference white, all the way down to at least 223 (the last white shown in the pattern). Terrible white clipping. Lowering the contrast and/or backlight does not change this. The blacks are pretty much spot on, clipping at just about reference black level, no BTB levels show up regardless of brightness level.

Next, I use Apple's built in calibration tool to create a new color profile. This helps the white a little. Now the test pattern shows white up to around 228, everything above is pure white. Still no where near the 235 reference. The black levels got a bit worse, showing around 19 and up.

I want to get at least 16-235 to the TV. Any help is appreciated.
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post #2 of 2 Old 03-11-2013, 08:18 AM
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Quote:
Originally Posted by derekwwww View Post

Has anyone done tests to verify Mac can output full 16-235 levels? And full 0-255 levels? I can't get full 16-235 and nothing from WTW and BTB. I don't think the problem is my TV.

Connecting my Macbook Air (2012, Mountain Lion) via Thunderbolt port to Samsung LED TV (UN50EH6000) using Thunderbolt-to-HDMI cable (Monoprice) shows lots of white clipping. A check in system preference/display/color shows the display profile used is called "HD 709-A". This was chosen for me when I plugged the mac into the Samsung.

Using AVSHD709 test patterns, the white clipping pattern shows no white flashing at all, including all the ones below reference white, all the way down to at least 223 (the last white shown in the pattern). Terrible white clipping. Lowering the contrast and/or backlight does not change this. The blacks are pretty much spot on, clipping at just about reference black level, no BTB levels show up regardless of brightness level.

Next, I use Apple's built in calibration tool to create a new color profile. This helps the white a little. Now the test pattern shows white up to around 228, everything above is pure white. Still no where near the 235 reference. The black levels got a bit worse, showing around 19 and up.

I want to get at least 16-235 to the TV. Any help is appreciated.

I am having the same problem with my late 2012 mac mini. I used the AVS contrast pattern on my WDTV and had no clipping well over 235. When playing the same file on the mini, I am getting up to 228-230 max. I know there was an issue with the new mini and crushing whites, but I am running the latest beta which allegedly fixes the issue (i can now see the grey lines in finder.) I also tried a script that forces OSX into RGB, and that did not help at all. I tried several different calibrations within OSX settings to no avail. Brightness seems to calibrate normally.. To make sure it was not the connection, I tried several different HDMI cables, a Mini DP/HDMI adapter and a Mini DP/DVI adapter. I would love to hear if anyone else has managed to get a good contrast cal.
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