Amazon Review by David
712 people found the following review helpful
Does not support full-resolution chroma (4K 4:4:4): only does 4K 4:2:0 via HDMI2
The TV is a mixed bag.
On the one hand, it’s a relatively sharp, saturated display (not that I can rate color reproduction with any expertise) at a good price. It nominally supports 4K@60Hz, unlike the Seiki (the only other contender in the 40", sub-1000 space).
The SmartHub software is very featureful and the remote is fancy, although like most Samsung products, the UI is pretty convoluted. In particular, depending on the display mode and context, the menus will have random items disabled without any explanation why (“Item not available”). You have to unplug HDMI devices in order to enable/disable Game Mode. Who knew? The UI and manual didn’t provide any hints. Along that vein, there seems to be no way to fully disable dynamic contrast: even with everything seemingly off, filling your screen 95% with black will make everything else on the screen suddenly dim, which is unfortunate but somewhat forgivable.
The main reason I’m writing this 2-star review, and the point of contention where I feel the product description here and on Samsung’s webpage is disingenuous and misleading, is that the display is not really 4K@60Hz in the way a consumer would expect, and certainly not “4 times full HD”. From my testing (and confirmed by a Samsung tech support rep), the display itself is only physically capable of 4:4:0 subsampling. You can look up the “Chroma subsampling” page on Wikipedia for some background, but it basically means that for every two vertical pixels, the display can only present one color (but different brightnesses). Unfortunately, HDMI2 does not define 4:4:0 subsampling as a valid subsampling, so when not in SmartHub the display is further downgraded to 4:2:0 subsampling, which is one color (but four brightnesses) for every block of 2x2 pixels. That means that while the display is 4K in luminance (brightness), it’s really only 1080p in chroma (color). In fact, an HDMI2 device can support 4:2:0 without actually supporting the higher bandwidth provided by the spec, so these “HDMI2” ports are only so in the most minimal way possible.
What this means is that the display is fine for TV, and probably fine for gaming (60Hz and general color reproduction is the only thing in this area setting it apart from the Seiki, which at time of writing is a third the cost). It is not good for displaying colored text or sharp drawings. To be clear, it is fine for displaying black-and-white text, since that’s purely luminance.
Frankly, I’m disappointed in Samsung for carefully omitting such a critical spec from their product listings, manuals, and website. It’s disingenuous of Samsung to highlight the HDMI2 advertising point when they don’t support its single most critical consumer-facing feature (4K @60 Hz with no subsampling).
Time to wait for round three of the sub-1000 40" 4K displays…