Color rendering
The Dell 2407WFP-HC is a wide gamut screen. From our past experience, this characteristic generates more fear than excitement for us. The Samsung monitors we have tested often rendered bizarre colors that were impossible to adjust or even calibrate. On the 226CW and 245T, this meant reds with an extreme vividness and an absolutely unnatural appearance.
Even before we put the 2407WFP-HC under the colorimeter, we started with a practical test. For several months now, I’ve been using a 2407WFP v4 that is calibrated. We changed it back to its standard profile in sRGB and put the new screen in its place.
Actually, the transition was easy and the quality of images was unaffected. For this reason and in the following more objective test with our colorimeter, we saw that color fidelity was good from the start. The Dell 2407WFP-HC is the first wide gamut screen with this appreciable characteristic and the sensor even confirms its gamut has indeed been extended. As you can see, we don’t always have to accept ultra-saturated colors on monitors.
Tests and measurements
As usual with the help of our probe we measured the difference between ideal colors and the ones actually displayed on the screen giving us a value called average DeltaE 94. We understand this data from our experience in this domain, however, this isn’t the case for everyone. We therefore are putting into place a new notation system based on our measurements, and which will immediately give you a better notion of quality in this area. Currently, there are no standards for color fidelity and manufacturers can pretty much say and do what they like (see the saga of the Samsung 226BW...). This system will only be for our website but at least it will be a step in the right direction.
By taking the differences between the measured colors and actual gamut found on the screen, a grade from A+ to F- will be given (and less if necessary). Of course, the higher up in the alphabet, the better the color fidelity. An A+ monitor will necessarily be factory pre-calibrated with an average DeltaE of less than 2 and with an extended gamut. Applied to current 24 inch products, this result in the following:
Color class fidelity
This new Dell does slightly less well here than its previous version. The former v4 had an average dE of 2.3 and the new is at 3.6. It’s still an excellent result and one of the best but color fidelity is a trifle below its predecessor.
The table above does not replace the usual detailed explanations. For those who are interested, here is the normal analysis of results. (Please note this time that the panel homogeneity section is found on the page devoted to each screen.)
The quality of colors is measured with the LaCie BlueEye Pro colorimeter, which in fact, is a Gretag colorimeter coupled to the software suite developed by LaCie.
Just to remind you, we work with a value called DeltaE. It represents a measurement between the color requested and the one really displayed on the monitor. The higher the result obtained, the less true colors are. More precisely, here is how to interpret the graphs:
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Delta E > 3 : the desired color is noticeably different from the one on the screen.
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2 < Delta E < 3 : color quality is satisfactory, but a graphic designer probably wouldn’t be content
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1 < Delta E < 2 : colors are accurate.
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Delta E < 1 : the result is perfect.
DeltaE by default 
You may have noticed that results are consistent with the grades above, and you can see that "A"s were given to screens with a starting average dE less than 2.5.
Besides color rendering, there is a point that concerns more and more people, depth of black. We measured a constant brightness of 200 cd/m² in white.
Depth of black (cd/m²) with white at 200 cd/m²
The Dell 2407WFP-HC surprisingly wins the title for the screen with the deepest black, formerly held by a TN. Normally, PVAs are the champions in this category and so the former order is re-established.
Most monitors are under the 0.30 cd/m² mark and so are at least satisfactory in this domain. The above measurements result in the following contrast ratios:
Contrast ratio measured at 200 cd/m² in white (xxx:1)
Each time, we analyze 18 color patches and 16 of these results are given in the following graphs:
PVA 6 ms : Dell 2407WFP-HCContrary to the Samsung 245T, not only is the 2407WFP-HC well adjusted when we take it out of the box, but also there is no color dominance – except in blue. However, as we will explain in the following page, the actual effect of this is minimal (even nil) because the eye is much less sensitive at this spectrum than in grays, for example. To illustrate this point, on the left are the desired colors and on the right those produced by the screen:
As you can see, the intensity of blue is noticeably different, however, it remains blue. It’s not like a gray that has pink hues and which can actually be bothersome. Therefore, there are still some surprises in terms of colors for this screen, however, nothing too excessive and its more in the extreme shades.
Our conclusion is that overall color rendering is sufficiently natural! However, fidelity is slightly less than on the previous v4 Dell we tested. This is still the best result we’ve obtained on a wide gamut, with a small reservation on the preset black level.
PVA 6 ms : Dell 2407WFP rev.4
TN 3 ms : Iiyama Prolite B2403WS
TN 5 ms : Samsung SyncMaster 245B
PVA 6 ms : Samsung SyncMaster 245T
MVA 8 ms : ViewSonic VX2435wmRight out of the box, the 2407WFP-HC is quite bright and close to 300 cd/m². At this level, black was measured at 0.40 cd/m² and we didn’t need our colorimeter to see that it was washed out. We preferred to adjust brightness to a more reasonable value and opted for 200 cd/m². This is obviously brighter than a CRT, but it’s comfortable and correct for all types of uses (games, movies, office, photo...) for an LCD. Going down 30% in brightness leads to a 50% reduction in the level of black and in our case this meant a final value of 0.21 cd/m². Or in the end, quite simply superb contrast!
To answer a reoccurring question: to calibrate a screen, is it always necessary to use a calibration probe. Modifying parameters in the OSD is a simple adjustment and often not enough, because differences vary from one color to the next. If we have too much blue in lighter shades, we can have too much red in darker ones, or vice versa. So, when we decrease the amount of red this affects all colors, whether they have too much or not. We are only changing color balances and putting dominances somewhere else. On the other hand, hardware calibration rewrites the entire color table that is used by the graphic card. It’s better but is more expensive. A good probe will cost 300 Euros and for this reason, we largely prefer when screens are factory pre-calibrated.
