Cheap monitors are generally not good if you want color accuracy because they use 6-bit color technology as opposed to 8-bit color technology. Basically a 6-bit LCD monitor can only produce 64 shades of Red, Green and Blue which means only 256k of actual colors can be produced. An 8-bit LCD monitor can create 256 shades of R,G,B which means an actual 16.7m of colors can be produced.
6-bit LCD monitors must use A-FRC (Advanced Frame Rate Control) to blend up to around 16m colors. It is known as temporal dithering. The pixels flicker between two color very rapid to blend a 3rd color that the LCD panel cannot normally produce. For example, the pixels would flicker between red and blue to create purple. The results are inaccurate colors and color banding issues when gradients are concerned as well as possible pixelation issues in some rare instances.
Basically all cheap monitors use 6-bit panels. All TN panels are 6-bit. Nearly all e-IPS panels are 6-bit with maybe two panel models that are actually 8-bit. More expensive monitors like the Dell U2410 use an 8-bit IPS or VA panel. The Dell U2311H uses a 6-bit e-IPS panel. It is still better than a monitor that uses a TN panel, but generally not ideal if color accuracy is important.
The NEC EA231WMi maybe something that is more appropriate. It too uses an e-IPS panel, but based on reviews from people who compared the Dell U2311H and the NEC side by side, the NEC seems to have less or no color banding issues. This indicates that the NEC EA231WMi may actually have an 8-bit e-IPS panel.
Those reviews are relatively old so they will probably say the NEC uses an 8-bit e-IPS panel. Even reviews of the Dell U2311h will probably say it uses an 8-bit e-IPS panel. That was a logical assumption at the time since all IPS panels that were manufactured before the e-IPS panel were 8-bit panels.
It was not revealed until this year (February 2011) that nearly all e-IPS panel models were in fact 6-bit panels.
thank you so much for your detailed answer
so basically i should search for true 8-Bit panel (H-IPS or VA )
so far i only saw U2410 (which i can't use because of res) and BenQ EW and VW class
which lead me to choose Benq
I've never had a chance to work with these brand
is it a good choice ? for exp EW2430
i like the specification on their website specially the 3000 Contrast Ratio !!
( i don't know is it okay to post the link or not so i prefer not to !)
but here is the details:
Screen Size 24"W LED-backlight
Resolution (max.) 1920 x 1080
Pixel Pitch 0.276 mm
Brightness 250 cd/m2
Contrast Ratio 3,000:1
Response Time 8 ms (GtG)
Display Area 531.36 x 298.89 mm
Display Color 16.7 million
Viewing Angle (L/R;U/D) (CR>=10) 178 / 178
Terminals D-sub / DVI-D / HDMI x2 / headphone jack / audio line in / audio line out
Horizontal Frequency (Max) KHz 30 ~ 83
Vertical Frequency (Max) Hz 50 ~ 76
Video Bandwidth (MHz) 205
Color Temperature Reddish / Normal / Bluish / User mode
Power Consumption 65W (max) / 25W (Eco mode)
Auto Switching Power Supply Built-in
Features Senseye® Human Vision Technology
Advanced Motion Accelerator (AMA)
Windows® 7 Compatibility
Speaker 2W x2
Adjustments Tilt (down / up) -5 ~ 20
Dimensions (HxWxD) 433.4 x 579.2 x 169.3 mm
Weight Net weight: 5.6 kg.
Gross weight: 7.9 kg.
Accessories (Standard) VGA / audio / USB cable
Product Color Black with metalic design
Vista Certification Premium
VESA Wall Mounting (mm) 100 x 100
It seems okay. The only issue I have with WLED backlight is that it does not produce true white light. WLEDs (or simply LED) use blue LEDs with a yellow phosphorus coating to imitate white. This sometimes lead to slightly bluish colors.
Based on what little information there is for this monitor it does seem to use an 8-bit VA panel. DCR (dynamic contrast ratio) is usually overstated; I prefer static contrast ratio which is the true measure of contrast.
you are right about lighting issue but if i want a better one i have to go with something like HP DreamColor which is way out of my league !
as you mentioned DCR is somehow useless
but real Contrast Ratio of 3000:1 seems to be pretty cool !
there is another version (EW 2430V) which have many more cool features
i hope they import it to US asap