LG IPS231P
Simon Baker, 13 July 2011

 

 

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Introduction

In our recent review of the Asus ML239H we talked about the recent market trends, showing an influx of IPS based screens into all segments, especially the 23" market. More recently this has also been combined with the 'technology of the moment' (as far as manufacturers seem to see it) which is W-LED backlighting. We've already tested the aforementioned Asus model and also NEC's IPS + LED offering, the EA232WMi. As many readers might realise, the IPS panels themselves are manufactured by LG.Display, and so when these become readily available and widely used, it is not normally long before LG themselves emerge with a screen using them. In this case we have LG's IPS231P monitor for testing which uses this same panel. LG also have another similar model available which is the IPS236V. That is a similar screen only differing in its design, ergonomics and a few features.

The IPS231P is marketed on their website based on its IPS panel and LED backlighting, with wide viewing angles, superb brightness and "spot-on-detail". We will test all of these points during the course of this review.
 


Specifications and Features

The following table gives detailed information about the specs of the screen:

Monitor Specifications Table

Size

23"WS (58.4cm)

Colour Depth

16.7m (6-bit + AFRC)

Aspect Ratio

16:9

Colour Gamut

~72% NTSC colour gamut (~sRGB)

Resolution

1920 x 1080

Panel Coating

Anti-glare (matte), 3H

Pixel Pitch

0.2652mm

Interfaces

1x DVI-D (HDCP), 1x D-sub

Response Time

5ms G2G (14ms ISO)

Design colour

Matte black bezel and stand

Static Contrast Ratio

1000:1

Ergonomics

Tilt -5 (front) ~ -15 (rear), 356 swivel, 110mm height, pivot mode

Dynamic Contrast Ratio

5,000,000:1

Special Features

Integrated speakers

Brightness

250

VESA Compatible

Yes

Viewing Angles

178/178

Physical Dimensions

(WxHxD with stand)
548.2 x 476.7 x 137.5mm

Panel Technology

e-IPS

Weight

With stand: 4.7kg
Without stand: 3.71kg

Backlight Technology

W-LED

Accessories

DVI cable, VGA cable, Power cord, audio cable

The IPS231P offers a fairly standard set of PC connections, with a single DVI-D and D-sub available. The screen is packaged with both cables but one can't help feel that extra interfaces like HDMI and DisplayPort would have been an extra welcome. Their IPS236V in fact offers an additional HDMI interface.

There are no integrated USB ports on this model which is a bit of a shame as I think those are useful when you want to connect external devices like cameras and printers. The screen is also missing any card readers, ambient light sensors etc. There are however integrated stereo speakers available along with an audio-in connection for external devices or your PC sound card.

Below is a summary of the features and connections of the screen:

Feature

Yes / No

Feature

Yes / No

Tilt adjust

DVI

Height adjust

HDMI

Swivel adjust

D-sub

Rotate adjust

DisplayPort

VESA compatible

Component

USB Ports

Composite

Card Reader

Audio connection

Ambient Light Sensor

HDCP Support

Touch Screen

Integrated Speakers



Design and Ergonomics


Above: front view of the screen. Click for larger version

The IPS231P comes in an all black coloured design with matte plastics used for the bezel and stand. The bezel is a thin 17mm wide along the sides and top, but a little wider at the bottom at 26mm. The top left hand corner has a light silver coloured logo saying "Flatron IPS231" and the middle of the lower bezel features the familiar LG logo.


Above: OSD operational buttons and power on/off. Click for larger version

The OSD operational buttons and power on/off are located in the bottom right hand corner and are situated on the front of the screen as shown. These are actual pressable buttons as opposed to being touch-sensitive. The screen looks a little more basic I think personally than other models and is a return to the more modest designs we have seen over the years. There's no glossy plastics, fancy designs, strange stands. Just a modest bezel and round plastic stand. That's not to say it's an ugly screen, but has perhaps more of a working office feel than a premium home screen perhaps.

The panel coating is a standard matte anti-glare (AG) coating. Some users complain about modern IPS panels having an overly aggressive coating. Personally I do not find the coating on this screen to be too bad but it can of course be subjective. The coating seems to be of a similar level to some of the other IPS panels like the Dell U2311H for instance and so is a little grainy if you look closely. The Asus ML239H has been a little smoother when we tested that.

  
Above: Rear views of the screen. Click for larger version (right)

The back of the screen is again a matte black plastic and is mostly enclosed. The monitor does maintain a reasonably thin profile as well which is attractive.


Above: more rear views of the screen. Click for larger versions


Above: Back of the screen showing interface options as well as power connection and audio-in. Click for larger versions

The back of the screen features interface connections for DVI and D-sub. The DVI connection is HDCP certified. There is also a standard kettle lead power connection as the screen has an integrated power supply. This does make it a little thicker than some of the ultra-thin profile screens which offer an external power brick. There is a single audio-in to connect sound from your PC as well. This can then be played through the integrated speakers. These provide a fairly tinny sound to be honest with no real bass. It should be ok for some casual office noises, the odd movie clip or mp3 but not much more.


Above: side views of the screen. Click for larger version (right)

From the side the IPS231P has a pretty thin profile and it looks pretty sleek as a result. There aren't any side USB connections on this model which you will sometimes see. That might have been a nice extra feature, especially considering this has the look and feel of an office display.


Above: Side views of the screen showing minimum and maximum tilt adjustments. Click for larger versions

The stand is a fairly chunky plastic design but does offer a decent range of ergonomic adjustments which is pleasing. There is wide tilt range but the screen doesn't tilt backwards as far as you might like (-5), instead offering a tilt towards you (downwards) which is probably more than anyone would ever need (-15). The tilt movement is a little stiff to use as well.


Above: front view of the screen showing maximum and minimum height adjustments. Click for larger versions

The height adjustment range is very good. At the lowest setting the bottom of the lower bezel is approximately 43mm from the desk so you can get a nice low height if you require. The full range of height adjustment is 110m. This is very stiff to move to a lower level, but smoother when increasing the height upwards.


Above: View of the base of the screen with rotating swivel plate. Click for larger version

The 356 swivel adjustment is much smoother to move and allows you to position the screen very easily. The bottom of the base has a rotating metal part which stays in the same position on your desk, while the rest of the screen moves from side to side.


Above: Rotated view of the screen

The rotation function to switch between landscape and portrait is available but again very stiff to use. Overall when you make adjustments to the screen, or even press the OSD buttons, the panel does feel quite wobbly and unstable. A light touch of the screen causes quite an obvious shake and so the stand is not providing the full support it could. It's good to see the range of adjustments available, but it's a shame they were not a little smoother and more stable.

A summary of the screens ergonomic adjustments is shown below:

Function

Range

Smoothness

Ease of Use

Tilt

(-5 front
-15 rear)

Quite stiff

Moderate

Height

110mm

Stiff down, smooth up

Moderate

Swivel

356

Smooth

Very easy

Rotate

Full

Very stiff

Difficult

Overall

Good range of adjustments but stiff movements in many areas and wobbly overall stability


The screen materials  are of a reasonable quality although as I've said already, it does feel a bit more basic than some of the fancy models (e.g. Asus ML239H). The build quality is moderate, and really in keeping with LG's other models in this kind of range. The wobble from the screen lets it down a little when it comes to build quality. There is a very faint high pitch noise from the screen if you listen very closely. You wouldn't notice this in normal use and you'd have to press your ear up to the top of the screen to really pick it up.

 



OSD Menu


Above: OSD operational buttons. Click for larger version

The OSD operational buttons for the screen are located in the bottom right hand corner. There are 5 actual pressable buttons as opposed to any touch-sensitive option. These are not labelled at all on the bezel. To the right is the power on/off button which does have a power logo to identify it. There is a small LED to the right of this button which glows blue during normal operation, and flashes blue on/off when in standby. You can actually even turn this off completely from within the OSD menu.

Pressing any of the buttons brings up the same introduction menu as shown above. This provides you then with 5 options relating to each of the OSD buttons. There is quick access into the 'mode' menu, auto adjust (analogue inputs only) and input selection. Obviously these quick access options are not quite as quick as other screens given that you have to make one press initially to even present you with the options. I'm not sure why LG didn't just label the options on the bezel in a light font and avoid the need for this first level of menu. This menu is always positioned in the bottom right hand area of the screen as well, and there is no option to change the on screen position from within the menu.

Pressing the mode button enters you into the selection of 5 preset modes as shown above. As you scroll from one to the other, the screen is split vertically in half to show you a before and after view of the picture. You can then select the preset you want to use. Strangely you cannot access these preset modes through the main menu sections so you have to exit the preset mode menu to get into the other controls. Some main menu options are not available in certain preset modes and those that are do carry over from one preset to the other unfortunately. e.g. if you change the brightness control in one preset it applies to all of them. This is with the one exception (oddly) of the sRGB mode which seems to retain its own brightness setting. In this mode, most of the other options are greyed out anyway.

Going into the main menu presents you with the full selection of options, split into 5 sub-sections. The first of these is the 'picture' menu which gives you options for standard controls like brightness and contrast. The bottom of the menu shows you arrows and labels telling you what each of the operational buttons will now do. You can easily scroll left and right as well as enter a given sub-section using the down arrow. The navigation is pretty easy and the menu is logical in layout.

The second section is the 'color' menu which gives you a decent range of adjustments to make. You can define the colour temperature here which includes a manually configurable 'user' mode. You can control the gamma setting of the screen as well which we will talk about later on. In some preset modes this menu section is greyed out and not available.

The third section is the 'display' menu which allows you to adjust things like clock and phase. This is only applicable when using an analogue connection from the D-sub interface, and so these options are greyed out here as I'm using DVI.

The volume menu allows you to change the volume of the speakers up and down, between 0 and 100. The highest setting is not actually that loud and the sounds is quite tinny with no bass.

The 'Others' menu allows you to control a couple of further options with the only interesting option really being the 'super energy saving' setting.

Strangely, there are also a few 'shortcuts' to activate / deactivate various features just by holding down one of the menu buttons on the screen. From left to right, holding down the buttons for around 5 seconds does the following:

1) Lock and unlock OSD buttons and menu
2) Demo mode on/off
3) Nothing
4) Nothing
5) Turn DDC/CI on/off

 


Power Consumption

In terms of power consumption the manufacturers spec states typical usage of 35W in normal operation and 0.3W in standby / off mode.

State

Power Usage (W)

Factory Default

34.8

Calibrated

20.7

Super Energy Saving On

19.3

Standby

0.7

We tested this ourselves and found that out of the box the screen used a slightly lower 34.8W of power. After calibration, where we had adjusted the brightness control and therefore the backlight intensity, this was reduced to 20.7W. In standby the screen uses only 0.7W of power. This was very comparable of course to the other W-LED + IPS models we have tested like the Asus ML239H and NEC EA232WMi. I also tested the screen with the 'Super Energy Saving' mode on. This seemed to make very little change, no matter what brightness setting I was at, only really dropping the power consumption by 1 - 2W. I'm not sure what this mode is supposed to do really. I have provided a comparison graph below of several screens we have tested:

 



Colour Accuracy, Black Depth and Contrast

The Panel and Backlighting Unit

The LG IPS231P utilises an LG.Display LM230WF3-SLB1 e-IPS panel which is capable of producing 16.7 million colours. The panel itself actually uses a 6-bit colour depth with frame rate control (A-FRC) to produce the 16.7m colours. This is different to regular 8-bit IPS matrices, but this is likely a measure taken to achieve a lower price point for these modern lower-cost displays. Studying detailed information from LG.Display's datasheet confirms the panel is indeed 6-bit+AFRC.

The IPS231P uses White-LED (W-LED) backlighting. The colour space of this screen is approximately equal to the sRGB reference (and around 72% NTSC) and the screen is therefore classified as a standard gamut model.


Testing Methodology

An important thing to consider for most users is how a screen will perform out of the box and with some basic manual adjustments. Since most users won't have access to hardware colorimeter tools, it is important to understand how the screen is going to perform in terms of colour accuracy for the average user.

I restored my graphics card to default settings and disabled any previously active ICC profiles and gamma corrections. The screen was tested at default factory settings using the DVI interface, and analysed using an X-rite i1 Pro spectrophotometer combined with LaCie's Blue Eye Pro software suite. An NEC branded and customised X-rite i1 Display 2 colorimeter was also used to verify the black point and contrast ratio since the i1 Pro is less reliable at the darker end.


Targets for these tests are as follows:

  • CIE Diagram - validates the colour space covered by the monitors backlighting with the black triangle representing the display

  • Gamma - we aim for 2.2 which is the default for computer monitors

  • Colour temperature / white point - we aim for 6500k which is the temperature of daylight

  • Luminance - we aim for 120 cd/m2, which is the recommended luminance for LCD monitors in normal lighting conditions

  • Black depth - we aim for as low as possible to maximise shadow detail and to offer us the best contrast ratio

  • Contrast ratio - we aim for as high as possible. Any dynamic contrast ratio controls are turned off here if present

  • dE average / maximum - as low as possible. If DeltaE >3, the color displayed is significantly different from the theoretical one, meaning that the difference will be perceptible to the viewer. If DeltaE <2, LaCie considers the calibration a success; there remains a slight difference, but it is barely undetectable. If DeltaE < 1, the color fidelity is excellent.



Default settings of the screen were as follows:

Monitor OSD Option

Default Settings

Brightness

100

Contrast

70

Color Temp

Preset

Preset

Warm

Gamma

2.2

Mode

User


LG IPS231P - Default Factory Settings



 

Default Settings

luminance (cd/m2)

273

Black Point (cd/m2)

0.30

Contrast Ratio

920:1

 

The out of the box performance of the IPS231P was reasonable. The CIE diagram on the left confirms that the monitors colour gamut (black triangle) very closely matches the sRGB colour space (orange triangle). It extends a little past the sRGB space in blues and greens in this 2D view of gamut. Default gamma was recorded at 2.0 average, leaving it 10% out from the target of 2.2. Keep in mind that the screens OSD gamma setting was at 2.2, so this is obviously a little out from reality. We will try to find the optimum screen gamma setting in a moment. White point was excellent here and  very close to the target at 6411k (1% deviance) which shows a good factory set up in this area.

 

Luminance was recorded at a high 273 cd/m2 which is perhaps not surprising given that the screen is set at 100% brightness by default. This was in fact a little higher even than the specified maximum brightness of 250 cd/m2. This should be easy enough to adjust later during our calibration. Even at this high 273 cd/m2 luminance, the black depth was a very good 0.30 cd/m2. This gave us a static contrast ratio of 920:1 which is excellent for an IPS panel.

 

Colour accuracy was mediocre at default factory settings with an average dE of 3.1, ranging up to a maximum of 5.6. The screen felt quite even to the naked eye although overly bright at these default settings and perhaps a little washed out. Some minor OSD adjustments can hopefully help improve the default set up for casual users who don't have access to a hardware calibration device.

 


 

Monitor OSD Option

Default Settings

Brightness

100

Contrast

70

Color Temp

Preset

Preset

Warm

Gamma

2.4

Mode

User


LG IPS231P - Default Factory Settings, Gamma 2.4



 

Default Settings, gamma 2.4

luminance (cd/m2)

274

Black Point (cd/m2)

0.30

Contrast Ratio

927:1

 

We wanted to test the screens other gamma settings to see if there was a better setting than the default 2.2 (which had returned measured gamma average of 2.0). We found that an OSD setting of 2.4 returned a gamma average of 2.2 (2% deviance) which was a better starting point. All other settings remained the same and we still retained an accurate colour temperature / white point of 6430k (1% deviance). Colour accuracy was actually improved a little as well with dE average now 2.0 (down from 3.1) and maximum pretty much as it was at 5.5 (down slightly from 5.6). Luminance still needs to be tamed, but adjusting the brightness control down to around 10% should return a more comfortable luminance of around 120 cd/m2. This gamma mode is definitely a better starting point and should provide a better out of the box performance than the default setting.

 

 

Calibration Results

 

I wanted to calibrate and profile the screen to determine what was possible with optimum settings and profiling. I used the X-rite i1 Pro spectrophotometer combined with the LaCie Blue Eye Pro software package to achieve these results and reports. An NEC branded and customised X-rite i1 Display 2 was used to validate the black depth and contrast ratios due to lower end limitations of the i1 Pro device.


LG IPS231P - Calibrated Settings

Monitor OSD Option

Adjusted Setting

Brightness

11

Contrast

70

Color Temp

User

RGB Controls

50, 47, 51

Gamma

2.4

Mode

User

 

Calibrated Settings

luminance (cd/m2)

120

Black Point (cd/m2)

0.14

Contrast Ratio

860:1

 

I remained in the user mode preset for this process and changing the color temp mode to 'user' allowed me to adjust the RGB controls from within the OSD menu individually. I followed LaCie's calibration process through, adjusting the OSD settings in line with the recommendations made in the process, and then letting the software carry out the LUT adjustments at a graphics card level and create an ICC profile. The screen does not feature a hardware LUT calibration option so other than the OSD alterations, the rest of the process is carried out at a graphics card level in profiling the screen.

 

The calibration was a success. The slight gamma discrepancy that we saw before (1%) had been corrected now to leave us with 0% deviance from the target of 2.2 and white point was basically spot on at 6507k. Luminance had been reduced to a more comfortable 120 cd/m2 after the adjustment of the OSD brightness control to 11%. Black depth was still very good at 0.14 cd/m2 and this gave us a very good calibrated static contrast ratio of 860:1. Colour accuracy was also improved nicely with dE average now 0.4 and maximum only 1.4. LaCie would consider colour fidelity to be excellent.

 

Testing the screen with various colour gradients showed very smooth transitions with no sign of any colour banding. There was some slight gradation evident in darker tones but overall no issues. There was also some slight temporal noise evident, particularly in darker tones if you look very closely. This is a result of the FRC algorithm used to produce the 16.7 million colour palette. It's not something you'd notice in practice to be honest, and you do have to look very closely to see it.

 

You can use our settings and try our calibrated ICC profile if you wish, which is available in our ICC profile database.

 

 

Calibration Performance Comparisons

 

 

I've provided a comparison above of the IPS231P against some of the other screens we have tested in a similar size range. Out of the box average dE was 3.1 on the IPS231P which was mediocre. It was better than the BenQ EW2420. That model used one of AU Optronics' AMVA panels with W-LED backlighting. Default colour accuracy of the EW2420 was worse at 4.8. The default colour accuracy of the IPS231P was comparable, although not quite as good, as some of the other 23" IPS models we have tested including the Dell U2311H (2.4), NEC EA231WMi (2.7) and Viewsonic VP2365wb (2.5). Even thought the IPS231P was a little higher at 3.1 this is a minimal difference really out of the box and still reasonable. The other 23" IPS + W-LED screens we have tested are the NEC EA232WMi (2.4) and the Asus ML239H (2.3). These screens are using the same panel as the IPS231P. The professional grade 23" NEC PA231W was better still at 1.3 dE average. A reasonable performance in terms of default colour accuracy from the LG IPS231P and only a little behind the competition really.

 

 

Once calibrated the dE average was reduced to 0.4. This would be classified as excellent colour fidelity by LaCie. It was not quite as low as some of the other screens here which reached down to 0.2 average, but in practice you would not notice any real difference here. Some of the professional range models from NEC are even more accurate. Professional grade monitors like the NEC PA series also offer other high end features which separate them from some of these other models, including extended internal processing, 3D LUT's and hardware calibration. These comparisons are based on a small selection of tests, so it should be remembered that other factors do come into play when you start talking about professional use. For further information and tests of a high end professional grade screen with hardware LUT calibration, you may want to have a read of our NEC SpectraView Reference 271 review.

 

 

 

The black depth and contrast ratio of the IPS231P were very good for an IPS panel. Calibrated black depth was 0.14 cd/m2 which was very close to the other 23" IPS screens we have tested (ranging between 0.13 and 0.17 cd/m2). The NEC EA232WMi is the closest rival to the IPS231P and had a slight better calibrated black depth of 0.13 but this is marginal. The LG was slightly ahead of the Asus ML239H though which had a calibrated black depth of 0.16. Contrast ratio was a very good 860:1 but it was a little behind a few the others in this regard. The NEC EA232WMi again was a little better with a 933:1 static contrast ratio thanks to its lower black point. However the LG was better than the Asus ML239H (749:1) and pretty much identical to the popular Dell U2311H (857:1). The BenQ EW2420 and Samsung F2380 with their AMVA and cPVA panels respectively offered some fantastic contrast ratios of ~3000:1 which IPS cannot compete with at the moment.

 

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Contrast Stability

I wanted to see how much variance there was in the screens contrast as we adjusted the monitor setting for brightness. In theory, brightness and contrast are two independent parameters, and good contrast is a requirement regardless of the brightness adjustment. Unfortunately, such is not always the case in practice. We recorded the screens luminance and black depth at various OSD brightness settings, and calculated the contrast ratio from there. Graphics card settings were left at default with no ICC profile or calibration active. Tests were made using an NEC branded and customised X-rite i1 Display 2 colorimeter. It should be noted that we used the BasICColor calibration software here to record these, and so luminance at default settings may vary a little from the LaCie Blue Eye Pro report.

OSD Brightness

Luminance
(cd/m2)

Black Point (cd/m2)

Contrast Ratio
( x:1)

100

270

0.30

898

90

252

0.28

899

80

237

0.27

877

70

221

0.25

882

60

204

0.23

887

50

188

0.21

895

40

172

0.19

903

30

155

0.18

863

20

139

0.16

867

10

123

0.14

881

0

107

0.12

888

 

Luminance Adjustment Range =  163 cd/m2

Black Point Adjustment Range =  0.18 cd/m2

Average Contrast Ratio = 885:1

The luminance range of the screen was decent enough at the top end although not as high as some modern screens. At 100% brightness control, the screen was able to offer a maximum luminance of 270 cd/m2 which is even a little higher than the advertised 250 cd/m2 maximum luminance. At the lower end the screen perhaps does not reach as low as you might hope, only ranging down to as low as 107 cd/m2. Some users may want to achieve a lower luminance than this, but it is not possible using simply the backlight control. Any further adjustments would need to be made at a digital white/black level using the contrast control, graphics card changes or altering the graphics card LUT. This would be at the sacrifice of contrast however.

A setting of around 10% at default settings should return a luminance of around 120 cd/m2 for comfortable day to day use in normal lighting conditions. If you carry out further calibration or adjustments of contrast or the individual RGB channels this of course may vary.

We have plotted the luminance trend on the graph above. The screen behaves as it should, with a reduction in the backlight intensity controlled by the reduction in the OSD brightness setting.

Black depth was good across the whole range, being between 0.30 and 0.12 cd/m2. This was good for an IPS panel and only a little behind some other competing (IPS based) models. This could also not compete with the modern AMVA and cPVA panels that we have seen.

Contrast remained stable across the range with an average static figure of 885:1 recorded based on a default uncalibrated state. These contrast measurements were plotted on the graph shown above.

 


Dynamic Contrast

The LG IPS231P features a dynamic contrast ratio (DCR) control, which boasts a spec of 50,000,000:1 (50 million:1).

Dynamic contrast ratio involves controlling the backlight of the screen automatically, depending on the content shown on the screen. In bright images, the backlight is increased, and in darker images, it is decreased. For this test I would use the colorimeter to record the luminance and black depths at the two extremes. Max brightness would be recorded on an all white screen once the DCR has caught up. Black depth would be recorded on an all black screen.

The DCR feature is only available in the 'user' and 'movie' presets from the 'mode' menu. The brightness control remains active in the OSD menu and is not greyed out as it is on some screens. There is actually no setting for this DCR in the menu so you cannot turn it on or off. Instead, if you enter these preset modes, it is always active.

 

Dynamic Contrast

Specified DCR Range

50 million : 1

Available in Presets

User, Movie

Settings

None

Max luminance (cd/m2)

132

Min Black Point (cd/m2)

0.21

Max Dynamic Contrast Ratio

631:1

The tests that we carry out to measure dynamic contrast ratio involve an almost completely white and almost completely black screen. In real use you are very unlikely to ever see a full black or full white screen, and even our tests are an extreme case. Carrying out the tests in this way does give you a good indication of the screens dynamic contrast ratio in real life situations however.

Carrying out this test in the 'movie' preset mode didn't seem to make use of the DCR at all. There was no noticeable change in the backlight intensity when changing between images of different levels of white and black, even when switching between an almost completely white, and an almost completely black image. Our colorimeter recorded maximum luminance as 132 cd/m2 and minimum black depth of 0.21 cd/m2. This gave us a contrast ratio which was in fact much lower than the the default static contrast ratio and was recorded at 631:1.

Having switched to the 'movie' mode, the colours and gamma of the screen were altered massively, making everything seem overly vivid and saturated, and with a higher gamma than needed. The section of the OSD that would normally let you control colour temp, RGB, gamma etc was now greyed out so this 'movie' preset mode was a fixed setting with an appearance which felt very unrealistic. This produced this lower contrast ratio of 631:1 which for all intents and purposes was just a static contrast ratio. The DCR didn't seem to work at all. Nothing particularly surprising considering some of the DCR performances we have seen from many other models.

However, the feature can work, but only in the most unrealistic and extreme circumstances. Like the Asus ML239H that we tested recently, if you display an all black screen (completely black) then the feature "works". You can see a change when viewing an all black screen which takes about 2 seconds to happen. The screen goes so dark that it seems to turn the backlight off completely after a couple of seconds. Unlike on the Asus, where you could view the OSD disappearing, if you have the OSD active on the LG then it keeps this from happening. You can detect it easily enough with the naked eye, and it only appears to happen on a 100% black screen. If you then return to any other image the screen comes back on and returns to the normal state within a couple of seconds again. This was the only way I could get the DCR to work at all. So the technology appears to be switching the backlight off completely which would account for the ridiculously high DCR of 50 million:1. In the right lab settings you can achieve this DCR (in fact its tending towards infinity:1 if you consider its black point is basically the backlight turned off = 0 cd/m2.). However, in practice you are never going to be able to see a DCR range like that. In fact in normal use the DCR doesn't seem to operate at all. Another marketing gimmick and a disappointing trend it seems.

 


Viewing Angles


Above: Viewing angles shown from front and side, and  from above and below. Click for larger image

Viewing angles of the LG IPS231P are very good, as you would expect from a screen based on an e-IPS panel. Horizontally there are very wide fields of view with a small contrast shift only really becoming noticeable from a fairly wide angle of about 45. Vertically, the contrast shift was a little more pronounced but the fields of view were still very good. Vertically there is a slight pink hue noticeable as you move your field of view away from a central position and at an extreme angle this turns a little yellow. This is only really a problem at extreme angles though. The panel is free from any off-centre contrast shift which you see from VA matrices, and this is why IPS technology is so highly regarded in the colour enthusiast and professional space. It is also free of the very noticeable contrast and colour tone shifts you see from TN Film panels vertically.

On a black image there is a slight purple hue, certainly less noticeable than some other screens like the Asus ML239H, when viewed from an angle but there is no obvious white glow that you can see from some modern IPS panels. There is no A-TW polarizer on this panel which is rarely used now in the market.



Panel Uniformity

Measurements of the screens luminance were taken at 35 points across the panel on a pure white background. The measurements were taken using BasICColor's calibration software package, combined with the NEC customised X-rite i1 Display 2 colorimeter. The above uniformity diagram shows the difference, as a percentage, between the luminance recorded at each point on the screen, as compared with the reference point of a calibrated 120 cd/m2. This is the desired level of luminance for an LCD screen in normal lighting conditions, and  the below shows the variance in the luminance across the screen compared with this point. It is worth noting that panel uniformity can vary from one screen to another, and can depend on manufacturing lines, screen transport and other local factors. This is only a guide of the uniformity of the sample screen we have for review.

Uniformity of Luminance

The luminance uniformity of the IPS231P sample was pretty good overall. The maximum deviations from the central measurement of 120 cd/m2 were as low as 102 cd/m2 along the left hand edge and up to the highest measurement of 121 cd/m2 around the central area. Overall 86% of the screen was within 10% deviance from the target which was good and 46% of it was measured within 5% deviance. The left hand edge of the screen was a little darker than the rest of the screen but you couldn't spot this in normal use.


Backlight Leakage

Above: All black screen in a darkened room. Click for larger version

As usual we also tested the screen with an all black image and in a darkened room. A camera was used to capture the result. Overall the appearance of an all black screen appeared pretty even in this test. There was some slight leakage of the backlight from the four corners, most noticeably from the bottom right hand corner. In normal use you wouldn't notice this and it was quite minimal thankfully.

 


General and Office Applications

The 23" screen size and high 1920 x 1080 resolution were very pleasant for office working, and although you do lose a bit of height vertically compared with a 1920 x 1200 screen, it was nothing too bad. Image quality was very crisp and sharp using the DVI interface, and although D-sub (VGA) was also very good, it was not quite as sharp on text I didn't think. The 0.265 mm pixel pitch was slightly smaller than a 23.6" 1920 x 1080 screen of course (0.2715 mm) and 24" 1920 x 1080 screen (0.276 mm), and so text size felt about right for every day use.

Default luminance of the screen was too high for prolonged office use at 273 cd/m2, although this was with the screen set at 100% brightness. For comfortable use in normal lighting conditions a setting of around 10% should return you a luminance of ~120 cd/m2. There was a specific 'text' preset mode available from within the OSD menu although it made the image a little more yellow than our calibrated 'user' mode. It probably won't be of much use to many if they set up their 'user' profile for normal day to day use.

The ergonomics of the screen offered a good wide range of adjustments. It was good to see a full range of height, tilt, pivot and swivel available although they were not the easiest to use sadly. At least you should be able to position the screen at a comfortable setting for your individual preferences. It was a bit of a shame not to see some USB ports available and there are no extra features like ambient light sensors and card readers which are often useful in office environments. These have been left off to keep production and retail costs down. At least there are some integrated speakers available I suppose for casual 'office' type sounds and occasional videos / music. However the sound is not that loud and quite tinny with no real bass. Don't plan on watching movies using these!

 
Above: photo of text at 1920 x 1080 (top) and 1680 x 1050 (bottom)

The screen is designed to run at its native resolution of 1920 x 1080 and at a 60Hz recommended refresh rate. However, if you want you are able to run the screen outside of this resolution. We tested the screen at a lower 1680 x 1050 resolution to see how the screen handles the interpolation of the resolution. At native resolution the text was very sharp as you can see from the top photograph. When you switch to a lower resolution the text is noticeably more blurry, even more so than some other screens we have tested. There is a lot of overlapping of the text across sub-pixels as you can see in the photo which results in this blurring. Native resolution is recommended where possible.

 


Responsiveness and Gaming

The screen was tested using the chase test in PixPerAn, a good bit of software for trying to quantify differences in real terms responsiveness between monitors. As a reminder, a series of pictures are taken on the highest shutter speed and compared, with the best case example shown on the left, and worst case example on the right. This should only be used as a rough guide to comparative responsiveness but is handy for a direct comparison of the impact of this setting:
 


23" 5ms G2G LG.Display e-IPS (W-LED)


23" 5ms G2G LG.Display e-IPS (W-LED) - Trace Free setting 40


23" 14ms LG.Display e-IPS (W-LED)

Unlike some other screens we have tested of late, there is not option in the OSD menu to turn the 'response time' up or down. You must therefore rely on LG's factory setting in this area. The IPS231P is rated by LG as having a 5ms G2G response time which implies the use of response time compensation (RTC) technology which is used to boost pixel transitions across grey to grey changes. The LM230WF3 panel itself is rated by LG.Display (the panel manufacturer) as having a 14ms ISO response time as well which signifies the black > white transition. Have a read about response time in our specs section if any of this is new to you.

I have provided a comparison of the IPS231P above against the two other screens we have tested which use the same panel as this screen. On paper the LG IPS231P should perform better than the NEC EA232WMi since it is using RTC and the NEC is not. The Asus ML239H is rated with a 5ms G2G response time as well so on paper appears to be the same as the LG model. In practice however the IPS231P performs far more like the NEC screen, which does not have any overdrive / RTC impulse applied to it. There is a noticeable motion blur and trail behind the moving car on the LG screen. The moving image is certainly less sharp than the Asus screen. Perhaps LG have decided to not apply much in the way of an RTC impulse here at all (if any)? Unfortunately you cannot control the level of RTC from the OSD menu so you cannot turn this up or down at all. On the plus side, without an aggressive RTC impulse seemingly being active on this screen, it is at least free of any noticeable overshoot. Where RTC impulses are applied too aggressively or not controlled well this can sometimes lead to dark / pale trailing behind a moving object which can be just as distracting and problematic as motion blur in the worst cases. There's no sign of any overshoot here on this model.

 


23" 5ms G2G LG.Display e-IPS (W-LED)


23" 14ms LG.Display e-IPS


23" 14ms LG.Display e-IPS


23" 8ms G2G LG.Display e-IPS


I have first provided a comparison of the LG IPS231P against three other competing 23" e-IPS models, this time models not using the same panel. These are all similar however with 23" e-IPS panels, but this time the backlighting is normal CCFL. From the test images above you will see that the IPS231P performs very similarly to the NEC EA231WMi and ViewSonic VP2365wb models which both have a quoted 14ms ISO response time figure. They do not use response time compensation technologies to boost pixel responsiveness and so show a fair degree of motion blur even in the best case images. The Dell U2311H is a bit faster than these other models. It has an 8ms G2G response time and does use RTC to boost pixel transitions well. Like the Asus ML239H we showed you before, this Dell screen is a fair bit faster than the LG IPS231P.

 


23" 5ms G2G LG.Display e-IPS (W-LED)


23" 8ms G2G Samsung cPVA (Response Time setting = Fastest)


24" 8ms G2G AU Optronics AMVA (W-LED)


24" 6ms G2G LG.Display H-IPS


24" 5ms G2G LG.Display e-IPS

I've also provided some comparisons of the IPS231P against some of the popular and recent 24" models in the market we have tested. As you can see, the IPS231P is a bit faster than the AMVA based BenQ EW2420, which to be quite honest, did not perform very well in this test. It is a little behind the cPVA based Samsung F2380 we tested recently which has an 8ms G2G response time. The Dell U2410 and HP ZR24W both use RTC and so their performance was better still and showed some of the best responsiveness of all of these models in practice.
 


23" 5ms G2G LG.Display e-IPS (W-LED)


23.6" 2ms G2G CMO TN Film (120Hz)


22" 3ms G2G Samsung TN Film + 120Hz

I've also included a comparison above against two gamer-orientated screens, both featuring heavily overdriven TN Film panels, and 120Hz technology. The pixel responsiveness of both of these is ahead of the IPS231P, and the 120Hz frequency allows for improved 120fps frame rates and the support of 3D content as well. The BenQ XL2410T does show some rather noticeable RTC overshoot in the form of dark trails behind the moving image (speech bubble and head) which is unfortunate, and a sign that the RTC impulse is too aggressive. The Samsung 2233RZ remains our champion in this test.


The responsiveness of the IPS231P should be fine for some casual gaming still but the screen is not as fast as many of the competing 23" and 24" models we have tested. It seems that LG have lead with an advertised 5ms G2G response time to capture interest in the screen, but in reality it behaves far more like a non-overdriven 14ms ISO rated screen. It is quite comparable to the NEC EA232WMi, EA231WMi and ViewSonic VP2365wb models, all of which are quoted with a 14ms response time and do not use overdrive technologies. That's not to say they are that bad, and in fact they are still reasonable for some light gaming and certainly fine for movies and other normal day to day uses. The IPS231P isn't as fast as well overdriven 23" models like the Asus ML239H and Dell U2311H though and so those would be a better choice if you want a gaming screen in this size range.


Additional Gaming Features

Aspect Ratio Control - The IPS231P supports aspect ratio control options through the OSD 'others' menu as shown above. There are only options for 'original' and 'wide' here though so they are fairly limited. Complete 1:1 pixel mapping is lacking here.

Preset Modes - There is no game' preset mode available in the menu sadly. The dynamic contrast ratio is only available in the 'movie' preset although we have already seen that this does nothing in real use unfortunately.

 



Input Lag

 

As usual I tested the screen in clone mode with a CRT to determine the level of input lag. This is something which can put off some gamers and is a delay between graphics card and monitor output. By hooking up a CRT you can show that  the LCD lags behind somewhat, which can affect users in some situations where they rely on the screen image being as fast as their inputs (e.g. fast FPS shooting games). Often, input lag is very low and probably wouldn't represent too much of a problem in real terms.

The input lag of the IPS231P was very low with an average of only 6.9ms. The delay ranged between 0 and 20ms maximum. This was very good and should not present any problems for gaming. It was a little faster than the Asus ML239H (15ms) and NEC EA232WMi (8.1ms) which was good.

 


Movies and Video

 The following summarises the screens performance in video applications:

  • 23" screen size makes it a reasonable option for an all-in-one multimedia screen, although quite a bit smaller than modern LCD TV's of course

  • 16:9 aspect ratio is more suited to videos than 16:10 format screens, leaving smaller borders on DVD's and wide screen content.

  • 1920 x 1080 resolution can support true 1080 HD resolution content

  • Digital interface DVI supports HDCP for any encrypted and protected content

  • Limited interface options available with 1x D-sub and 1x DVI only. Would have been useful to feature HDMI or DisplayPort here as they are increasingly popular and very useful for external Blu-ray / DVD player connectivity.

  • Black depth and contrast ratio are very good for an IPS panel. Detail in darker scenes should not be lost due to these measurements.

  • Dynamic contrast ratio is available but does nothing in practice unfortunately.

  • 'Movie'' preset mode is available from the preset menu. This boosted the colours and made them more vivid and cartoony. Might be useful if you want to set up a separate preset how you want for movie viewing and keep the 'user' preset available and set up for normal PC use. For me I found it too unrealistic.

  • Moderate pixel responsiveness which should be able to handle fast moving scenes in movies without issue.

  • Wide viewing angles thanks to e-IPS panel technology meaning several people could view the screen at once comfortable and from a whole host of different angles.

  • Good ergonomic adjustments available from the stand allowing you to obtain a comfortable position for movie viewing.

  • Some very slight backlight leakage from the corners of the panel which was not really noticeable at all in practice. Thankfully no leakage along any of the edges which has the potential to become distracting when watching movies, especially where black borders are present.

  • Integrated stereo speakers on this model for some light sounds for movies if needed. These are not very loud and are very tinny with no real bass to them.

 


Conclusion

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The influx of new IPS panels into the 23" market is certainly making it a very competitive area and its always interesting to see what LG themselves will offer based on one of their own panels. In the case of the IPS231P I think I can sum this screen up as: a good general all rounder which would suit casual day to day or office work well.

The design and features of the screen are fairly standard really and its a simple, modest display and stand. It's good to see the decent range of ergonomic adjustments available here which will suit an office environment well, although they were let down a little by their wobbly feel and stiffness in some cases. There's no fancy extras and only a D-sub and DVI interface available so this isn't a screen for those wanting a multimedia display for lots of devices, or something that will look stunning sat on their desk.

However, what the IPS231P does do, it does well enough. Colour accuracy, black depth and contrast ratio were all very good and even the out of the box settings were decent enough. Viewing angles were wide, uniformity was decent and responsiveness was ok. Again, a good screen generally all round thanks to its e-IPS panel technology, but there's nothing which grabs you really here. The input lag was very low which was good, but then if you are looking at a gaming screen then you would probably want something with a better response time.

In terms of retail cost the IPS231P currently sells for ~150 GBP which is very competitive. In comparison at the time of writing the Asus ML239H is ~180, the Dell U2311H is ~200 and the NEC EA232WMi is ~240. So there is quite a saving to be made if you just want a decent display for all round office type work and don't need any fancy extras.
 

Pros

Cons

Very good colour accuracy, black depth and contrast ratio

Dynamic Contrast ratio did not work at all

Decent ergonomic range

Mediocre responsiveness in practice

Competitively priced in this sector

Wobbly stand and stiff movements

 

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