bz268

Hi,

I was checking out the Samsung website. They made a big deal about how their LCD TV reached 92% of the NTSC color gamut thingy.

I also was checking out the Sharp website. They didn't make a big fuzz about color gamut but did make a big deal about their 4-wavelength and 5-wavelength back light.

I don't know... So... the bigger the #, the better the color? How do you tell what # it is from a TV? (plasma and lcd?)

Siddig

The only way to tell any of that is with a grey scale chip chart, a color chart, a waveform monitor, and a vectorscope. Basically, all these companies are using oddly worded language to sway new consumers with a "well this TV has this" factor. Unless you are a video tech, its all really pointless reading.

SiGGy

Actually... I can explain a bit further. There's a bit more to answer in his question.

The reason Sharp doesn't have any color Gamut number is because it's less than 50% of the NTSC chart. Meaning it can only display less than 50% of the NTSC color chart. You can find this information looking for professionally claibrated sets on AVS forums.



LCDs inherently have problems trying to fulfill the complete NTSC colorchart. You'll find most LCD displays are around 40% of the NTSC color chart. This is also why LCDs usually have real poppy colors. Especially overly saturated greens or called green push. Easily seen when watching football on newly planted grass fields.

To help alleviate this the new Samsungs use *colored* LEDs (red,green,blue) for back lighting. Helping that area of the screen reach it's true desired color by modifying the back light color. The only setback to this is it's a compromise depending on the color needed in that areas of the screen. They can only put so many back light bulbs behind each square inch of screen. So while the Samsung display is capable of showing *up to* 80% it will have a hard time doing it simultaneously around the entire screen. In other words you can only have the color led back light bulbs help compensate for so many colors at once. The video may require both more green and red compensation. So the LEDs have to compensate and do both at once making them 1/2 as efficient. Verses if it only needed to extend the green range it could do so by lighting mostly the green bulb. Giving a greater measured green performance.

Another huge gain from the LED backlight is they can be turned off, or dimmed. Thus improving your blacks and subcontrast.

In the end the Samsung will have better measured color and better blacks than the Sharp because of the LED backlighting.

... in regards to numbers from the manufacturers

You need to find professional calibration results from a neutral 3rd party. The reason I say this is there are no set standards by which companies are required to measure their products.

So for example if a company was measuring their contrast ratio (a measurement how bright a picture it can show over how black (dark) picture can show) and they took the bright measurement then shut the TV off to take the black measurement would you consider those results legitiment?

The only standardized testing that I'm aware of is THX certification. And even it has it's flaws...

bz268

You mean Samsung use a bunch of color fluorescent lights in the back?

SiGGy

Samsung uses *many* colored lights yes, florescent NO. They're LED lights; I think I stated that a few times. LED = light emitting diode. (only the latest Samsung models use LED backlighting) Also 3-4 LEDs may only light up a small portion of the viewing screen.

Sharp uses a large single (CCFL) Cold Cathode Fluorescent Lamp that stays on the entire time and is uniform in (white) color and brightness. Or a similar type of florescent lamp (FFL).


To explain what you're seeing here... (**note** This is not an example of the actual Samsung screen. Just a general sample of how the technology could be implemented)

The top blue square is the entire LCD back light screen with a circle cut out to show the LED lights.

The next photo below is zoomed in to show the actual LED lights themselfs.



Samsung probably doesn't use 3 seperate LEDs for red/green/blue. They probably have one LED bulb that is has all 3 built into it. And also probably have the lights arranged differently.

bz268

So... the Samsung TV (I am shopping for a 37" model) has a panel in the back that has a bunch of LED shining the screen in the front? Like one of those "We Are Open" LED sign?

IlliNorge

That's excited neon gas. Look at the screen of a CRT and you will see the same red, green, and blue dots. In the case of an LCD, a liquid crystal is the medium and the diodes are behind it.

SiGGy

Maybe he's talking about one of those scrolling digital signs? I dunno, I don't have any more time for this though.