by Mike McNamee Published 01/11/2005
The Dell colour control is quite sophisticated as it allows you to set the RGB levels ndependently, as well adjusting the brightness; there is no adjustment for contrast. It is quite normal to not calibrate an LCD before profiling it (something you would ordinarily do on a CRT to get the electron guns closer to optimum before you profile). The Dell control panel was very simple so we decided to try out and measure a number of options to see what ifference it made! The Optix XR Pro will deliver data for further analysis when set up to do so. The evaluation routine fires all the colours of the Macbeth Chart at the detector and compares the actual with the expected results and reports the error on its graphical trend chart. These are the data we took for further analysis.
The settings we employed were the 0% Brightness condition, 50% Brightness setting and a setting determined by the X-Rite. It is worth noting that LCD monitors running at below maximum brightness will last longer and be more stable with time in terms of the gradual dimming which occurs. In summary, the results were as follows:
ISO 3664:2000 - Viewing Conditions for Graphic Technology and Photography calls for a screen luminance of between 75 and 100cd/m2 so you can see that the Dell exceeds this by some way, even when it was set to zero and the brightness adjustment. Whilst this does not actually comply with the ISO standard, it is one of many things that probably does not in the average studio! For example the room illumination level is specified at 32lux, which is dangerously dark for an office - you would be falling over all the time! The brighter LCD display enables you to judge colour under more realistic room lighting conditions as the additional brightness of the screen compensates for a more user-friendly working environment! The danger comes in judging the shadow areas of your print - in real-world terms, you may think you can see detail in a groom's trousers but it won't come out in a print. There is no hard and fast rule for getting over this issue, possibly the best way is to watch the colour numbers in Photoshop and learn, by experience, what will and will not reproduce. It is a common disappointment after you have invested loads of money monitor calibration kit that these issues still come back and bite you, but do not expect perfection when comparing a transmissive monitor image and a reflective print - they are not the same and never can be! The ISO committee is still resolving these issues so there is little we can do about it at present. Some pertinent advice is given by Bruce Fraser in their book, Real World Color Management, which is to try and match brightness not colour of your viewing environment and to place your monitor and light box at right angles to each other, so that you have to physically turn to make a comparison. It is one of the nonsense features of ISO 3663 that they call for 32 lux lighting in the room and 2000 lux in the viewing booth - put 2000 lux on in a booth and it is as if there is a searchlight in the room - fat chance of getting anywhere near 32lux! What do they expect us to do, keep switching lights on and off? In reality the standard does not cover print to screen comparison, it is at best a compromise. The foregoing is not an attempt to damn the efforts of the ISO committee, more an explanation of why you are always going to have some trouble matching tone and colour across screen to print.
In monitor calibration an error of less than 2 ΔE is considered to be a match. As you can see from the data table above, all attempted conditions resulted in a "match". However, processing the data into a more refined colour audit spreadsheet revealed even more detail about the performance. The colour error was reasonably constant around the gamut, the blues and cyans were, in the main, the least accurate colours. The Light Skin Tone had an error of just 0.14 Lab ΔE, actually too small to register on the graph. The overall ΔE2000 error measurement had an average of 0.66. To put this into perspective the best we have ever done in a print is around 2.5ΔE2000.The weighted errors are evenly split across the Lightness, Saturation and Hue channels. On average, the screen was about 0.38% brighter than target and this error varied little with the brightness setting on the monitor. The data are tabled in full so that you can see just how good the monitor performed. In the Lab error plot the arrows are so small that some of them might not even reproduce - this was a very accurate result indeed!
In Practice In practice we found that we could see deeper into the shadows on the monitor than we could into the equivalent print. This finding has been replicated with other LCD screens and whilst it is a source of annoyance it seems to be fact of life - as we said earlier you have to check and watch your values in the info palette.
Size 20.1" Viewing area
Width 47.2 cm Depth 22.9 cm Height 38.9 cm
Weight 8 kg
Viewing Angle 176° Vertical & Horizontal
Max Luminance 300cd/m2
Contrast Ratio 600:1
Power Consumption 75 watts
Connectivity DVI-D and 4xUSB ports on bezel
Panel swivel (50° left/right), tilt (20°back/5° forward) and pivot to support portrait and landscape orientations.
Height-adjustable stand with 100mm of adjustment.
Judging on the bare statistics this is a spectacular performer by any standards. The RRP is £507, but they can be found on the web at nearer to £350. At this price you can afford to buy a monitor and the X-Rite XRPro at £207 making a grand total of £557, still inside what you used to pay for a mid-end CRT- yes I think the LCD is about to find its place in the sunshine! Remember you can also watch your favourite movies in wide screen mode and do picture in picture and other clever stuff! www.dell.co.uk
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