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Dithering
Not only is there dithering, the dithering is not that good. I can clearly see two different types of dithering being used: spatial dithering and temporal dithering using frame rate control. The dithering is most noticeable on dark colors, like on this page: http://www.lagom.nl/lcd-test/black.php
The firmware can be updated by the user, but only in Windows. Out of the box with the original firmware, the spatial dithering looked like a fixed pattern of colored noise. After updating to the latest firmware, the spatial dithering looked like simple 2x2 ordered dithering. With both firmware revisions, the temporal dithering looked like faint noise scrolling up or down, and some shades had rolling diagonal lines.
Here is an emulation of the spatial dithering before the firmware update:
I kid you not. It really was that bad. Keep in mind that this is not an exact representation, but it's a good example of what I saw.
Here is an emulation of the spatial dithering after the firmware update:
If you don't see anything wrong, look closer. While the new dithering is much better, I could still see it. On top of that, there was still frame rate control, which added noise and rolling lines to some shades.
I really hate to trash this monitor based on the dithering because other than that, it is a nice monitor, but a $3500 color-critical monitor should not have visible dithering, especially when the main selling point is 30-bit color with no dithering or frame rate control: "A full 30-bit pixel is sent from the DreamColor Engine to be displayed on the HP 30-bit LCD panel with no dithering or frame rate control." Source: http://h20202.www2.hp.com/Hpsub/downloads/DreamColor_and_LP2480zx_FAQ_June08a.pdf
The dithering is definitely coming from the DreamColor Engine. 1080i over HDMI disables the DreamColor Engine, and there's no dithering there. The dithering is present in all other modes on both DVI and HDMI. I did not have a way to test DisplayPort, but that shouldn't matter. A 24-bit source on a 30-bit monitor should not have dithering either.
It's possible that the NEC monitors (LCD2490WUXi and LCD2690WUXi) also have dithering, but if that's the case, I can't tell. On the HP, I can clearly see it.
Panel
According to the service menu and the TCO'99 compliance certificate, this monitor has an LG LM240WU5 panel.
Service menu:
TCO'99 compliance certificate:
http://h20195.www2.hp.com/V2/GetDocument.aspx?docid=0900a5a582f9ad2d&cc=hr&lc=hr
Uniformity
I took white and black luminance measurements on nine parts of the screen:
I did not see any major uniformity problems, but it's not perfect. This monitor does not have uniformity compensation like the NEC monitors do.
I did not see any backlight bleeding at all:
The white dot in the corner is the mouse cursor.
Viewing Angles
This monitor definitely has the A-TW polarizer, which prevents black from blooming at slight angles. It has the same faint red and green glow that the NEC monitors have.
The A-TW polarizer causes a red glow when looking from the right at extreme angles, which is why there's a slight red tint in that last picture. Based on my experience with the A-TW polarizer, some units will have the red tint from both sides, probably depending on the direction the polarizer was put on. There's no gamma shifting at any angle, as you can see.
Color Spaces
This monitor has the ability to emulate color spaces and provides seven color space options:
FULL
AdobeRGB
Rec. 601
sRGB
Rec. 709
DCI P3 Emulation
User-7
FULL has very intense reds. Think hot pink, but red instead.
AdobeRGB looks very good to me. AdobeRGB has the same red and blue primaries as sRGB, so reds aren't overly intense. I've often recommended against wider gamut monitors for desktop use because then the colors are oversaturated, but that's mostly due to wider gamut monitors having overly intense reds.
sRGB still doesn't look right to me. The reds are too pure and dark. I have never seen a perfect sRGB reference monitor, so it could be right for all I know, but sRGB is supposed to represent a typical monitor's gamut, yet the reds look nothing like any monitor I've seen. The NEC LCD2490WUXi better represents a typical monitor's gamut. Strangely enough, AdobeRGB has reds closer to what I expect even though sRGB is supposed to have the same red primary.
Rec. 709 has the same problem with reds as sRGB, which isn't surprising since they both share the same gamut.
I'm not familiar enough with the other color spaces to comment on them. They are used for video production.
User-7 can only be set using the calibration kit, which I didn't have.
The monitor only gives you control over luminance and color temperature. The gamma can only be set with the calibration kit.
All the presets can be calibrated using the calibration kit:
It looks like the monitor can be calibrated to any gamut, but I did not see options for esoteric gamma curves like sRGB.
The software will only work with the colorimeter that comes with the calibration kit, so I couldn't test it.
Brightness and Contrast
FULL:
White = 236.750, 236.668
Black = 0.238, 0.237
Contrast = 995:1, 999:1
AdobeRGB:
White = 162.831, 162.820
Black = 0.173, 0.172
Contrast = 941:1, 947:1
AdobeRGB, lowest brightness:
White = 44.978, 44.599
Black = 0.048, 0.048
Contrast = 937:1, 929:1
sRGB:
White = 81.908, 81.820
Black = 0.101, 0.099
Contrast = 811:1, 826:1
This monitor can go down to a very low brightness without panel blocking. This is how all LCD monitors should be. The brightness ranges from around 45 cd/m² to around 235 cd/m².
The white point is also set in the backlight itself without panel blocking. The RGB LEDs can be seen adjusting the white point when the brightness is changed. White looks very pure regardless of the brightness.
The native contrast is also relatively high. This combined with the A-TW polarizer gives this monitor the best black I've ever seen in an IPS panel, but "CRT-class black" is a bit of an exaggeration. It's more like PVA-class black. This is the first time I've seen an IPS panel come anywhere close to 1000:1 contrast.
Scaling and Video Modes
Scaling options:
Fill to Screen
Fill to Aspect Ratio
One-to-one
Overscan
The overscan option is useless. It cuts off five pixels from all sides, then scales to fill the screen. Why would anyone want to do that? There is no way to have overscan while preserving the aspect ratio, and five pixels is often not enough for television broadcasts.
Action shot:
1080p and 720p are scaled perfectly without overscan.
1080i over DVI does some sort of bob deinterlacing, and it looks like it does something to the image before that, like maybe converting to 960x540 first.
1080i over HDMI also looks that way but with better deinterlacing that doesn't bob.
480p is treated as 3:2. Yet another monitor that can't scale 480p properly.
480i doesn't work over DVI, and I don't remember testing it over HDMI.
None of the modes are scaled properly over component. All of the modes have 2.5% overscan, and "Fill to Aspect Ratio" doesn't scale correctly, causing the image to be too wide.
The DreamColor Engine is disabled for the analog inputs and interlacted modes over HDMI, which means you're stuck with the excessively wide gamut in those cases. There is a saturation control, but there's only so much you can do with that.
DVI and HDMI are always full range, regardless of the color space.
This monitor is a bust for anything other than 1080p and 720p full range RGB over DVI and HDMI. This monitor was obviously not designed for video.
Lag
I tested this monitor against the DoubleSight DS-263N. I could not get a stable image on the HP over DVI when connected to a DVI splitter, but the results were usable. HDMI provided a more stable image and produced the same results.
DVI (left = HP, right = DoubleSight):
HDMI (left = HP, right = DoubleSight):
Every shot showed that the HP is exactly one frame behind the DoubleSight over both DVI and HDMI, which puts the lag at a little over one frame compared to a CRT (20-25 ms). Overdrive made no difference. This is consistent with what people have been getting on the HP LP2475w, so they both probably have the same amount of lag. It's not as bad as the NEC monitors, but I could still feel it. I doubt most people would notice it if there are no other lags present, but I wouldn't recommend this monitor for anything latency sensitive.
Response Time
The response reminds me of S-PVA panels. There is much less motion blur than I've seen on other IPS panels, but there's this effect, like I'm always seeing at least two frames on the screen at once. Overdrive didn't make a significant difference on that effect. I've only seen that in S-PVA panels until now.
Overdrive can be turned on and off, but with it enabled, I kept encountering subtle artifacts in static images.
For example, this image causes a faint flickering dot to appear in one of the four copies, depending on where it is on the screen:
This is the first time I've encountered a monitor where overdrive produces artifacts on static images.
Flicker
This monitor has a very subtle flicker that I can see when I move my eyes, sort of like a DLP, except not as strong. I don't think most people would notice it, and I was not bothered by it. It's not like a CRT at 60 Hz or anything. When viewed with a camera, the viewfinder shows the monitor flickers from top to bottom. I wonder if they incorporated some sort of backlight scanning to improve the perceived response time.
Coating
The sparkly coating is back, sort of. It doesn't seem to be as bad as the older S-IPS panels, but it's not as smooth as the NEC monitors or the Planar and DoubleSight monitors.
Noise
I did not hear any buzzing when I put my ear up to the back unlike with most CCFL monitors, but I did hear a fan, which can be heard from a normal viewing position in a very quiet room.
Unpacking and monitor pictures
There's not enough room to rotate the monitor without tilting it back first. Why was it designed like that?
Defects
I didn't see any dead or stuck pixels, but I did spot a mark embedded in the panel:
Conclusion
I returned it for the mark embedded in the panel, and I decided not to get a replacement due to the dithering. If it weren't for the dithering, I'd say it's one of the best monitors out there, but I don't know what to think of it now.
I think most people would be better served by the NEC monitors. They cost half as much and perform nearly as well, without visible dithering. The LCD2490WUXi is good for sRGB and HDTV material, and the LCD2690WUXi is good for AdobeRGB material.
The most unique feature of the HP is the ability to emulate color spaces, but not many people need that, and I don't know how accurate it is since sRGB doesn't look right to me.
The HP can only be internally calibrated using the $350 calibration kit, bringing up the total cost.
The HP has better contrast due to being able to lower the brightness and change the white point without panel blocking, but that only makes a minor difference. Most of the magic comes from the A-TW polarizer, which the NEC monitors also have.
The HP has more inputs, but the analog inputs aren't even scaled properly, so what's the point? You can get one of the NEC monitors along with the Blackmagic Intensity Pro for component inputs and still have money left over. There are also plenty of component to VGA transcoders available. The DVI ports can be used as HDMI ports with a simple HDMI-DVI cable.
The HP has slightly less lag than the NEC monitors, but not less enough to justify the price. It's still over a frame behind a CRT. If you care about lag, get the Planar PX2611W or the 23" Apple Cinema Display.
Not only is there dithering, the dithering is not that good. I can clearly see two different types of dithering being used: spatial dithering and temporal dithering using frame rate control. The dithering is most noticeable on dark colors, like on this page: http://www.lagom.nl/lcd-test/black.php
The firmware can be updated by the user, but only in Windows. Out of the box with the original firmware, the spatial dithering looked like a fixed pattern of colored noise. After updating to the latest firmware, the spatial dithering looked like simple 2x2 ordered dithering. With both firmware revisions, the temporal dithering looked like faint noise scrolling up or down, and some shades had rolling diagonal lines.
Here is an emulation of the spatial dithering before the firmware update:
I kid you not. It really was that bad. Keep in mind that this is not an exact representation, but it's a good example of what I saw.
Here is an emulation of the spatial dithering after the firmware update:
If you don't see anything wrong, look closer. While the new dithering is much better, I could still see it. On top of that, there was still frame rate control, which added noise and rolling lines to some shades.
I really hate to trash this monitor based on the dithering because other than that, it is a nice monitor, but a $3500 color-critical monitor should not have visible dithering, especially when the main selling point is 30-bit color with no dithering or frame rate control: "A full 30-bit pixel is sent from the DreamColor Engine to be displayed on the HP 30-bit LCD panel with no dithering or frame rate control." Source: http://h20202.www2.hp.com/Hpsub/downloads/DreamColor_and_LP2480zx_FAQ_June08a.pdf
The dithering is definitely coming from the DreamColor Engine. 1080i over HDMI disables the DreamColor Engine, and there's no dithering there. The dithering is present in all other modes on both DVI and HDMI. I did not have a way to test DisplayPort, but that shouldn't matter. A 24-bit source on a 30-bit monitor should not have dithering either.
It's possible that the NEC monitors (LCD2490WUXi and LCD2690WUXi) also have dithering, but if that's the case, I can't tell. On the HP, I can clearly see it.
Panel
According to the service menu and the TCO'99 compliance certificate, this monitor has an LG LM240WU5 panel.
Service menu:
TCO'99 compliance certificate:
http://h20195.www2.hp.com/V2/GetDocument.aspx?docid=0900a5a582f9ad2d&cc=hr&lc=hr
Uniformity
I took white and black luminance measurements on nine parts of the screen:
I did not see any major uniformity problems, but it's not perfect. This monitor does not have uniformity compensation like the NEC monitors do.
I did not see any backlight bleeding at all:
The white dot in the corner is the mouse cursor.
Viewing Angles
This monitor definitely has the A-TW polarizer, which prevents black from blooming at slight angles. It has the same faint red and green glow that the NEC monitors have.
The A-TW polarizer causes a red glow when looking from the right at extreme angles, which is why there's a slight red tint in that last picture. Based on my experience with the A-TW polarizer, some units will have the red tint from both sides, probably depending on the direction the polarizer was put on. There's no gamma shifting at any angle, as you can see.
Color Spaces
This monitor has the ability to emulate color spaces and provides seven color space options:
FULL
AdobeRGB
Rec. 601
sRGB
Rec. 709
DCI P3 Emulation
User-7
FULL has very intense reds. Think hot pink, but red instead.
AdobeRGB looks very good to me. AdobeRGB has the same red and blue primaries as sRGB, so reds aren't overly intense. I've often recommended against wider gamut monitors for desktop use because then the colors are oversaturated, but that's mostly due to wider gamut monitors having overly intense reds.
sRGB still doesn't look right to me. The reds are too pure and dark. I have never seen a perfect sRGB reference monitor, so it could be right for all I know, but sRGB is supposed to represent a typical monitor's gamut, yet the reds look nothing like any monitor I've seen. The NEC LCD2490WUXi better represents a typical monitor's gamut. Strangely enough, AdobeRGB has reds closer to what I expect even though sRGB is supposed to have the same red primary.
Rec. 709 has the same problem with reds as sRGB, which isn't surprising since they both share the same gamut.
I'm not familiar enough with the other color spaces to comment on them. They are used for video production.
User-7 can only be set using the calibration kit, which I didn't have.
The monitor only gives you control over luminance and color temperature. The gamma can only be set with the calibration kit.
All the presets can be calibrated using the calibration kit:
It looks like the monitor can be calibrated to any gamut, but I did not see options for esoteric gamma curves like sRGB.
The software will only work with the colorimeter that comes with the calibration kit, so I couldn't test it.
Brightness and Contrast
FULL:
White = 236.750, 236.668
Black = 0.238, 0.237
Contrast = 995:1, 999:1
AdobeRGB:
White = 162.831, 162.820
Black = 0.173, 0.172
Contrast = 941:1, 947:1
AdobeRGB, lowest brightness:
White = 44.978, 44.599
Black = 0.048, 0.048
Contrast = 937:1, 929:1
sRGB:
White = 81.908, 81.820
Black = 0.101, 0.099
Contrast = 811:1, 826:1
This monitor can go down to a very low brightness without panel blocking. This is how all LCD monitors should be. The brightness ranges from around 45 cd/m² to around 235 cd/m².
The white point is also set in the backlight itself without panel blocking. The RGB LEDs can be seen adjusting the white point when the brightness is changed. White looks very pure regardless of the brightness.
The native contrast is also relatively high. This combined with the A-TW polarizer gives this monitor the best black I've ever seen in an IPS panel, but "CRT-class black" is a bit of an exaggeration. It's more like PVA-class black. This is the first time I've seen an IPS panel come anywhere close to 1000:1 contrast.
Scaling and Video Modes
Scaling options:
Fill to Screen
Fill to Aspect Ratio
One-to-one
Overscan
The overscan option is useless. It cuts off five pixels from all sides, then scales to fill the screen. Why would anyone want to do that? There is no way to have overscan while preserving the aspect ratio, and five pixels is often not enough for television broadcasts.
Action shot:
1080p and 720p are scaled perfectly without overscan.
1080i over DVI does some sort of bob deinterlacing, and it looks like it does something to the image before that, like maybe converting to 960x540 first.
1080i over HDMI also looks that way but with better deinterlacing that doesn't bob.
480p is treated as 3:2. Yet another monitor that can't scale 480p properly.
480i doesn't work over DVI, and I don't remember testing it over HDMI.
None of the modes are scaled properly over component. All of the modes have 2.5% overscan, and "Fill to Aspect Ratio" doesn't scale correctly, causing the image to be too wide.
The DreamColor Engine is disabled for the analog inputs and interlacted modes over HDMI, which means you're stuck with the excessively wide gamut in those cases. There is a saturation control, but there's only so much you can do with that.
DVI and HDMI are always full range, regardless of the color space.
This monitor is a bust for anything other than 1080p and 720p full range RGB over DVI and HDMI. This monitor was obviously not designed for video.
Lag
I tested this monitor against the DoubleSight DS-263N. I could not get a stable image on the HP over DVI when connected to a DVI splitter, but the results were usable. HDMI provided a more stable image and produced the same results.
DVI (left = HP, right = DoubleSight):
HDMI (left = HP, right = DoubleSight):
Every shot showed that the HP is exactly one frame behind the DoubleSight over both DVI and HDMI, which puts the lag at a little over one frame compared to a CRT (20-25 ms). Overdrive made no difference. This is consistent with what people have been getting on the HP LP2475w, so they both probably have the same amount of lag. It's not as bad as the NEC monitors, but I could still feel it. I doubt most people would notice it if there are no other lags present, but I wouldn't recommend this monitor for anything latency sensitive.
Response Time
The response reminds me of S-PVA panels. There is much less motion blur than I've seen on other IPS panels, but there's this effect, like I'm always seeing at least two frames on the screen at once. Overdrive didn't make a significant difference on that effect. I've only seen that in S-PVA panels until now.
Overdrive can be turned on and off, but with it enabled, I kept encountering subtle artifacts in static images.
For example, this image causes a faint flickering dot to appear in one of the four copies, depending on where it is on the screen:
This is the first time I've encountered a monitor where overdrive produces artifacts on static images.
Flicker
This monitor has a very subtle flicker that I can see when I move my eyes, sort of like a DLP, except not as strong. I don't think most people would notice it, and I was not bothered by it. It's not like a CRT at 60 Hz or anything. When viewed with a camera, the viewfinder shows the monitor flickers from top to bottom. I wonder if they incorporated some sort of backlight scanning to improve the perceived response time.
Coating
The sparkly coating is back, sort of. It doesn't seem to be as bad as the older S-IPS panels, but it's not as smooth as the NEC monitors or the Planar and DoubleSight monitors.
Noise
I did not hear any buzzing when I put my ear up to the back unlike with most CCFL monitors, but I did hear a fan, which can be heard from a normal viewing position in a very quiet room.
Unpacking and monitor pictures
There's not enough room to rotate the monitor without tilting it back first. Why was it designed like that?
Defects
I didn't see any dead or stuck pixels, but I did spot a mark embedded in the panel:
Conclusion
I returned it for the mark embedded in the panel, and I decided not to get a replacement due to the dithering. If it weren't for the dithering, I'd say it's one of the best monitors out there, but I don't know what to think of it now.
I think most people would be better served by the NEC monitors. They cost half as much and perform nearly as well, without visible dithering. The LCD2490WUXi is good for sRGB and HDTV material, and the LCD2690WUXi is good for AdobeRGB material.
The most unique feature of the HP is the ability to emulate color spaces, but not many people need that, and I don't know how accurate it is since sRGB doesn't look right to me.
The HP can only be internally calibrated using the $350 calibration kit, bringing up the total cost.
The HP has better contrast due to being able to lower the brightness and change the white point without panel blocking, but that only makes a minor difference. Most of the magic comes from the A-TW polarizer, which the NEC monitors also have.
The HP has more inputs, but the analog inputs aren't even scaled properly, so what's the point? You can get one of the NEC monitors along with the Blackmagic Intensity Pro for component inputs and still have money left over. There are also plenty of component to VGA transcoders available. The DVI ports can be used as HDMI ports with a simple HDMI-DVI cable.
The HP has slightly less lag than the NEC monitors, but not less enough to justify the price. It's still over a frame behind a CRT. If you care about lag, get the Planar PX2611W or the 23" Apple Cinema Display.
