Sony HX75x "dragging blacks"

esdbag

Standard Member
My Sony KDL-40HX753 (40", LED backlit LCD TV, 2012 model) seems to have a low-medium issue with the so called "dragging blacks" (could be also called smearing, or a type of ghosting), which means for example that when a black object is moving on white background, the black object leaves a dark fading trail behind it.

The panel's response time seems otherwise good, movement looks clear. The dragging blacks issue is only visible on very contrasty pictures with large areas of constant colors, such as when scrolling through a webpage with white background and thick black or dark objects on it. The issue is not visible with regular text, probably because the lines in text are not usually thick enough.

I have the TV connected to my computer via a DVI-HDMI cable and have it set at 1920 x 1080 resolution with 60 Hz refresh rate (and 32 bit colours, but that's standard nowadays).

The issue looks very similar, although much less severe than what is seen in this YouTube video I saw while searching the internet for info about the issue:


In that video the dragging blacks/smearing issue looks much worse than on my TV though, but the principle is same. The dragging blacks issue is visible even on slow movement, the trail is just shorter with slow movement and longer with fast movement.

I have read that many if not all LCD TVs suffer from the dragging blacks issue, to a varying degree. On some TVs it's very noticeable, and on some almost invisible. Gladly on my TV it's not that bad, but still enough for me to notice it when using the TV as a computer monitor.

Picture adjustments don't seem to make much of a difference to the issue, including whether MotionFlow is on or off (even though movement looks otherwise sharper with MotionFlow on).

I understood that Sony had some line-up of TVs that suffered from dragging blacks more than others, but then Sony improved it in later models. My TV is a quite new model (the HX753 came out early this year (2012)), so I'd like to ask that is it normal for this product line (Sony HX75x, or HX85x even) to have this issue? I can live with it, but it would be nice to know if that issue is common/normal on this line-up of Sony TVs.
 
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esdbag

Standard Member
After a quick test with Windows' Paint I found out that in order for the "dragging blacks" issue to appear on my KDL-40HX753, the black must be pure black or almost pure black. The trailing is visible against almost any color background, as long as it's uniformly colored. The trailing seems to be most visible on a pure white background.

In Paint, I made cubes on a large uniformly colored background and ran manual movement tests by simply moving the window, thus effectively moving the black cubes on the background color. I changed the black level of the cubes step at a time and repeated the movement test to observe the effect. Here are my observations:

1. Pure black 0/0/0 (Red/Green/Blue) cube causes the most visible trail. The trail might be visible enough, so that it could distract in some rare cases.

2. Almost pure black 1/1/1 (R/G/B) cube causes noticeably less trailing while moving, although it still could distract in some rare cases.

3. Still almost pure blacks between 2/2/2 and 6/6/6 cause again less trailing, at 6/6/6 it's almost invisible. Most likely never distracting at these levels.

4. 7/7/7 cube (can be still considered black) causes practically no visible trailing at all. At this point the only noticeable thing is the typical motion blur caused by LCD's response time.


The amount of trailing/dragging blacks can be reduced or even removed by increasing brightness so that black is a few steps brighter than the darkest black the TV can show, however this obviously makes blacks look less deep, which could be noticeable in a dark room.


In addition to pure black, pure red color also causes an almost identical trail as pure black does, with the difference that any brightness of red causes trailing, as long as it's close to pure red (1-255/0/0 Red/Green/Blue). Red color's trailing disappears when green and blue levels are increased enough (e.g. about 255/25/25).

Has anyone else noticed trailing/dragging blacks and reds on new (2012) Sony TVs, especially on the HX75x series? I would be curious to know if this is normal for this model.
 
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