2007WFP gradient banding

[B4RK0D3]

Originally posted by: xtknight
Here is another good pattern to use to test banding:

http://www.prad.de/en/monitore/color_gradients_4.html

Save the picture and resize it so you can see easier. After some (rather tricky) gamma and OSD contrast adjustments I've gotten my VP930b so it's quite hard to see transitions between colors and those that do appear are very subtle. Changing brightness does not affect the banding (at least on my monitor), which is actually quite a godsend. I can increase brightness without turning my grayscale into a sloppy mess. Interestingly enough I have never, ever noticed banding in real usage, and having discovered the VP930b dithering you'd think I'd have the eyes for this stuff.

xtknight - Unfortunately, scaling a gradient in an image will actually create banding in the image itself, so that is not really a great example.

Also, I've decided to keep the 2007WFP. Very, very slight banding on large gradient images is not enough to push me away from this LCD. I've also spent a day with this monitor, testing it on many different applications (uncalibrated). I'm very happy with it so far, and at this point I would recommend it. The use I get out of the monitor is primarily for graphic design, photo editing, Flash, games (HL2/CS, Quake 4, Oblivion, etc.)

No ghosting, no tearing, color is EXCELLENT, consistent backlighting, very ergonomically friendly, and overall attractive build. No complaints moving from my 19" CRT

 

[orion23]

Does this "problem" affect both teh 2007WFP and the 2007FP models?

What exactly is "banding"? is it like an "un-even shade"

When I compare the screen saver background on my 2007WFP and my Dell LCD TV W2600, I can see a solid black background on the LCD TV, but it is not so solid on the 2007WFP, kind of like black and black cherry

 

[Heartbreaker]

Originally posted by: orion23
What exactly is "banding"? is it like an "un-even shade"

Run this. (esc gets you out)
http://xtknight.atothosting.com/tools/gradlin-v0.2-fs.exe

Then run it again with 16 bit color. What banding is should be very clear.
Right click the screen background, properties-> display-> settings-> color quality -> medium (16 bit).

Every second row which should have been smooth continuous tone is now banded. This is banding. When in 32 bit mode, every second row should be a continuous smooth tone.

 

[orion23]

OK
In 32bit mode, every second row is almost smoth (I can see a few lines)
In 16bit mode, I can definately see lines instead of smoth tones

Is that right?

Is this also the case with the 2007FP?

and thanks guidryp

 

[JMWarren]

Yeah, I'd say from what your discribing that your problem isn't as bad as mine.

Try setting your video card to cloned output. Then hook up the DVI and VGA and switch between them. I see a marked difference do you?

 

[orion23]

Sorry guys, I really don't understand the issue completely.

I plugged my second monitor, a Dell LCD TV 1260X768 and the program looks exactly the same on both.

 

[xtknight]

Originally posted by: B4RK0D3
xtknight - Unfortunately, scaling a gradient in an image will actually create banding in the image itself, so that is not really a great example.

Good point, but what if you scale it to 2x, 4x, 8x, 16x, etc?

 

[JiOwon]

Ok I've looked at this some more and this what I think.
xtknight's gradient tools do show banding with the 2007WFP but not my old CRT. In fact the previously mentioned T41 laptop screen also shows the banding but it is not as evident as is with the 2007WFP. I believe that is because the 2007WFP shows more detail and is much brighter.
Here are some photos of what I can see when running xtknight's full screen gradient test -

http://members.iinet.net.au/~json/stuff/blue-grey.jpg
http://members.iinet.net.au/~json/stuff/red-green.jpg

I took two photos in portrait of the areas I can see the most banding (the darker end of the scale).
A quick test on an IBM/Lenovo Thinkvision L200p (analogue in this case) showed much smoother gradients when using xtknight's full screen tool - I'll try DVI on that screen when I get back to work in a few weeks.

As for banding in other applications I believe it's mostly to do with the fact that this screen shows so much more detail than I'm used to. The 2007WFP simply blows away the T41 screen and my old 'tron crt when it comes to brightness and sharpness. Some of the banding I noticed with the 2007WFP was just gradient banding caused by jpeg compression that was too subtle to notice on my other screens - looking very hard on the crt I could make out similar patterns in banding on some pictures which would definately either be compression or rendering related.

So apart from xtknight's gradient tool and some home made gradients I'm pretty happy. I still would like to know what xtknight's tool is showing the banding like it is - oh well.
As for for photos and homemade graphics I haven't noticed any banding - that wasn't already in the image itself - same goes for the yellowpages site I would think - that's too subtle to notice on the crt even with max contrast and brightness.

 

[JiOwon]

JMWarren: try this program - http://www.ykwong.com/checkemon.html

run the colour gradients and let me know if you see a difference between the 128 shade line and the 256 shade line - for me they're almost the same which to me suggests I'm not getting anywhere close to 256 shades.

B4RK0D3: how does that look on your 2007wfp? Can you see a big difference between the 128 and 256 lines?


If this was the case then why do games, photo's and graphic art look so good on this screen. Could it be that the monitor just has a problem showing gradients like this?

 

[Heartbreaker]

Color banding is insideous, because you won't know when banding you see is part of the image or part or a screen rendering issue. Since it seem to affect dark tones more, it won't be as obvious. In blue sky photos for example, which is one place where banding makes itself known quite often (annoyingly so).

 

[JiOwon]

That's the thing - I have 1000's of photos I've taken over recent years - some of which have clear skies with gradients ranging from the pale horizon to the rich blue above. None of those photos show any banding what so ever.

 

[Heartbreaker]

Though it is there. It clearly will show up in some circumstances. After I knew it was there, I would always be looking for it and wondering.

I am surprised this simple gradient test doesn't make it into more reviews.

Have you tried hooking up via VGA and seeing if it goes away?

To me those who think this is brought out by DVI because DVI is more accurate are mistaken. If anything it should be better under DVI as DVI is perfect it should record tones as 80 80 80 79 79 79 78 78 78 78 77 77 77 77 76 76 76 etc.. Clearly it is going 80 80 80 80 80 76 76 76 etc...

There is no reason for DVI to show more banding unless it is faulty in some way.

 

[JiOwon]

Yes it's certainly skipping some colours and repeating ones it has diplsayed which is causing the banding effect.
Running the checkemon application on the T41 screen and the 128 line clearly shows evenly sized bars - ie. none being repeated to creat a thicker bar. The 256 line is quite different from the 128 line above it - more difficult to make out the individual bars which is what I would expect. On the 2007WFP even on the 128 line some of the colours are repeated showing thicker bars in some areas along the line. This happens more so on the 256 line creating the banding effect which prompted my op.

I have both analogue and digital cables connected so I can switch between either of them fairly quickly. The banding effect is less noticable when using VGA - still some colours on the 128 line are repeated but not as much as DVI. The 256 line still shows banding as well but I would say the colour is being repeated less often so less banding.

 

[JMWarren]

I got my third 2007FP today. Still has banding issues. It looks like it's going back. This is simply not good enough.

Anyone got any last ideas?

 

[xtknight]

Originally posted by: JiOwon
If this was the case then why do games, photo's and graphic art look so good on this screen. Could it be that the monitor just has a problem showing gradients like this?

I don't know. Personally, I think it is much ado about nothing, unless you are extremely picky.

The analog connection is just more immune to imperfections because it itself is not perfect. When you look at text on the VGA connection, it appears blurry. Pictures and even the color components themselves get blurred, especially at resolutions like 1600x1200 and 1680x1050.

 

[JMWarren]

xtKnight - I've gotta disagree with you on this one. I'm convinced the problem stems from the DVI decoder on the panel. Since this is handeled by the video card in the case of VGA this is why it's not present on VGA.

As to the people who say it's not visible in photos, it most definatly is, if your eyes are attuned to it. If I'm processing photos I've gotta know that the banding is actually in the photograph and not just my lousy display.

 

[xtknight]

The 20" S-IPS panels may indeed have a DVI problem but I still think VGA is part of the reason CRTs perform better. As for the few CRTs that have DVI, I'd be curious as to how they'd perform. If you're willing to spend the money and have widescreen, I don't think anything but an expensive Eizo will beat the NEC 20WMGX2 in this aspect. It's too bad NEC doesn't offer a non-widescreen display that is just as good for a reasonable price.

 

[Heartbreaker]

Originally posted by: xtknight
I don't know. Personally, I think it is much ado about nothing, unless you are extremely picky.

The analog connection is just more immune to imperfections because it itself is not perfect. When you look at text on the VGA connection, it appears blurry. Pictures and even the color components themselves get blurred, especially at resolutions like 1600x1200 and 1680x1050.

I also disagree. If the analog display is capable of displaying level 10 11 12 13 14 15 16 17 18 19 20 without no jumps and the LCD displays 10 10 12 12 16 16 18 18 20 20 then the Analog display is more accurate. It is a big deal if you edit pictures.

I am using a 21" Trinitron right now at 1600x1200 and the text is very nice and sharp. Not blurry at all, but it is smooth, the pixels blend together. I don't need to see individual pixels. In fact that is usually referred to as an artifact in video circles. SDE - Screen door effect.

 

[JMWarren]

My 21" CRT uses DVI but I belive it's DVI-A not DVI-D.

 

[xtknight]

I mean, it doesn't matter for the casual user, and it's probably unnoticeable to most people still in real-life pictures. Having used LCDs for 2 years I can stand by this. If you need a "perfect" (more or less) grayscale then you're going to have to look elsewhere.

The screen door effect doesn't occur on CRTs because they have a much smaller dot pitch, and because of how the pixel holes are arranged on the shadow mask/grille. (It doesn't have to do with the input connection.) With LCDs, pixels are just RGBRGBRGB, or BGRBGRBGR, depending on your panel. Without knowledge of how the TFT in this monitor is driven, it is impossible to know whether VGA can address more colors than DVI can, or if it can't due to there being an ADC. Is the TFT not a digital display device? Like I say, I don't know how the whole thing fits together so I can only speculate. What I do know is that to get rid of this effect, Eizo had to use a 10-bit gamma system.

The real question is, is the banding on this display worse than on other LCDs?

PDF about grayscale on LCDs: http://www.radiforce.com/en/support/pdf/wp_en_04_001_grayscale.pdf

 

[Heartbreaker]

Originally posted by: xtknight
I mean, it doesn't matter for the casual user, and it's probably unnoticeable to most people still in real-life pictures. Having used LCDs for 2 years I can stand by this. If you need a "perfect" (more or less) grayscale then you're going to have to look elsewhere.

Most casual users would never notice they are in 16 bit mode. So that is hardly saying much. LCD can certainly do better than this. My DEll 2405 did not show any banding IIRC. I put up Gradients. The guy who bought did the same while testing it before buying it.

The screen door effect doesn't occur on CRTs because they have a much smaller dot pitch, and because of how the pixel holes are arranged on the shadow mask/grille. (It doesn't have to do with the input connection.) With LCDs, pixels are just RGBRGBRGB, or BGRBGRBGR, depending on your panel.

Actually the dot pitch is often around .24 mm on Trinitrons like I am using right now so it is similar dot pitch. The thing is in the vertical direction. There is no separation between pixels. Abutting pixels have no gaps at all in the vertical direction. Trinitron as also much more like LCD in that it is an RGB stripes across the screen. Cleartype even works quite well on a a trinitron (though is less necessary than in LCD). The big difference is the gaps, which are sharply defined on LCD.

The real question is, is the banding on this display worse than on other LCDs?

As mentioned above, I would say yes. I think there are many banding free LCD. The 2007fp and LG L2000C seem to be standouts for producing more than typical amount.

 

[imported_greyhound]

Re the gradients posted by JiOwon, my L2000c has much less DVI banding than this - none in blue and only slight in red and green. The gray banding is more noticeable but not nearly as severe as this.

Adjusting contrast level does help to some extent.

 

[yacoub]

Originally posted by: guidryp
First off lets all make sure we know what we are talking about.

The Gradlin program should display ever second line as a smooth continuous tone change:
row 1: Red Blocks
row 2: Red Smooth
row 3: Green Blocks
row 4: Green Smooth
row 5: Blue Blocks
row 6: Blue Smooth
row 7: Grey Blocks
row 8: Grey Smooth

Put graphics card in 16bit mode, properties-> display-> settings-> color quality -> medium (16 bit) and now:

row 1: Red Blocks
row 2: Red blocky
row 3: Green Blocks
row 4: Green blocky
row 5: Blue Blocks
row 6: Blue blocky
row 7: Grey Blocks
row 8: Grey blocky

Now if you graphics card is in 32 bit mode (color quality highest 32 bit) and see any of the even numbered rows as anything but smooth toned, you have banding and it will be difficult to use the monitor for photo editing and you may see this occaisionally when watching videos etc...

So if you only see it from 3 inches, I wouldn't worry about it, If you see it on a CRT, check your settings, I have never seen it on a CRT in highest color (32bit) mode.

Flip back and forth between 16 bit and 32bit to see the difference. 32 bit will undoubtedly be better, but really it should be perfect smooth tones.

FWIW, my four+ year old Sony SDM-X72 17" LCD displays the gradients beautifully with the first of each color being blocky and the second band perfectly smooth. DVI, 32bit, X800XL videocard.
My 2007WFP should be here in a day or two. I will compare and post results.

Here is a link to a pic of the results.

 

[JiOwon]

Just looked at those gradients (xtknight's and checkemon) on a Samsung SyncMaster 153V flat panel, Inspiron 6400 laptop(1280x800 screen) and again on the T41 laptop. The 2007WFP is bar far the least capable monitor when it comes to displaying smooth gradients.
I'm going to have a chat with Dell and see what the official word is.

 

[JMWarren]

Dell played completely clueless with my 2007FP.

Customer Service, Tech Support, Second Level.