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Let There Be Light

by Mike McNamee

The most frequent query to come up at printing and colour management seminars is 'why are my prints darker than my screen?' This is an almost universal cry for uncalibrated system users and has the same underlying cause - the screen is too bright!

But this is actually only one side of the problem. Yes, your screen may be too bright, but your print viewing conditions are likely to be too dark, thus compounding the problem.

Now there is an international standard for this carry-on, called ISO 3664. This was published in the 70s and has had two revisions, one in 2000 and the latest ISO 3664:2009 was implemented in 2012. For the casual user, these things only serve to confuse matters still further. This is especially true because the standard's main target audience is printing press and press services. There is a standard set-up specified for viewing prints and (almost as an afterthought) for comparing prints against screen, soft proofs. The main thing that a press operator is concerned about is the match between a hard-copy proof and what the press is producing; throwing a monitor into the system only serves to complicate matters.

Despite these reservations there are some things to be gleaned and taken on board from ISO 3664. The illumination level of the viewing area should be at one of two intensities, according to what you are doing. These are called P1 and P2 as follows:

"P1 Critical comparison of PRINTS
This is recommended when comparing an original and its reproduction, or when comparing a sample print with a production run. The higher illumination level enables better judgment for evaluation of higher density zones (shadows). The illumination
level is 2,000 lux at print level.

However, it is also recommended to make a comparison with the P2 conditions, or the actual conditions that will be used to view the images, to get an overall view of tone reproduction.

P2 Practical appraisal of PRINTS
This is recommended when one wants to make a judgment on individual prints. This viewing condition is not recommended for comparing prints against one another, with the exception of comparing a print with its image shown on a monitor. The lower illumination level of P2 makes this task easier. You should be aware that such a comparison, monitor vs print, should only be performed when the monitor and print viewing light have the SAME white point, usually D65 or D50. The illumination level is 500 lux at print level."

In practice the main difference you will notice is that you can see more shadow detail at the higher luminance viewing level.

The standard specifies that the screen luminance of your monitor should be between 75 and 100 cd/m2. Some calibration software calls up 120cd/m2 for laptops. Personally we like 75cd/m2 - apart from anything else it extends the life of the monitor! This rather low value should be compared with the figures that are bandied about for iPads, Macbook Pros and some low-end monitors of up to 400cd/m2. This is the most common finding for those who suffer prints that are dark compared with their screens - they are working at the default luminance. The prime requirement for a screen calibrator and its software is that you can choose and regulate the screen luminance AND check it afterwards! Often luminance settings are under 'advanced' buttons or 'pro mode'. The current rash of Retina screens have only served to make matters worse - they are never going to look like a print!

Light Quality
For critical applications the quality of the light is important. This is measured by a parameter called the Colour Rendering Index, the CRI. The sun has 100% CRI, as do incandescent bulbs such as tungsten and tungsten halogen; this is essentially perfect. The colour temperature also has to be chosen and correctly set. For viewing and setting up monitors the two main values are D50 and D65. Things now get complicated; D65 light is not just a colour temperature of 6,500°k but also includes a specified amount of UV in its spectrum (the same goes for D50 and 5,000°k). This is so the level of excitation caused by the UV onto optical brightening agents is under control - it is also the major difference between the 2000 and 2090 editions of ISO 3664. Practically the effect is that D65 produces more reaction from OBAs than it used to, and so any papers with OBAs will appear more blue. This is important because most proofing papers do not contain OBAs but most papers used in press printing do, an anomaly the industry has always had to deal with. However, screens have no OBA effect within them and so the printed page is likely to look different to the screen for this reason alone! As if this were not complicated enough, the CRI also influences metamerism and so this has to be tied down as well - if you are not ready to throw the towel in yet you soon might be! A final thing to bear in mind is that D50 looks very yellow to the eye and although you rapidly get used to this, if you are switching about from sunlight to D50 it looks alarmingly yellow. D65, on the other hand, is quite cool and if you are moving about an office or domestic environment it can look very cold. For this reason some users (and this includes Professional Imagemaker) use around 5700°k. This sort of quirk can drive fanatics to distraction, but they also have their walls painted neutral grey to go with a grumpy wife!

Go back now to the start of this feature - 'the print is darker than the screen'; this is perhaps what really matters to photographers, they mainly do not require to colour match, just to create a pleasing colour balance. Providing the metamerism is not so high as to distort monochromes then a lower standard of CRI/metamerism might be acceptable providing it is the correct brightness.

To cut through all this, the user needs specific advice:

  1. Use a monitor calibrator but get one which sets and checks the luminance value and also checks the residual colour error when you have finished. A simple before-and-after toggle screen is not helpful - you need to know.
  2. Set your monitor to 75cd/m2 and your viewing area to 500 lux. A compact fluorescent tube as described in the call-out will give 6500°k and 500 lux at about 2 feet distance. These tubes have a CRI of about 86% - outside of the specification, but OK for most screen-to-printmatch purposes. If you need to match two prints closely you can drop the angle-poise down to 14-inches and have a better look at the shadows!
  3. Take your time when assessing prints, but try to make your colour changes in ACR and Photoshop quite quickly as prolonged knob twiddling invariably leads to errors - give it long enough and you will fully adapt to any colour! For similar reasons two sets of eyes are better than one, get a partner or colleague to look over your shoulder every now and again (in photographic competitions this is sometimes called a judge, but they appear too late on the scene).

Maybe the Print is Wrong?
In our experience all printers from the Epson 3880 upwards (ie larger) are very accurate and only rarely are they the source of a print-screen mismatch (they are, in fact, calibrated before they get to you). Even so, you might be unlucky or even be printing incorrectly. Not using colour management can mess your prints up very considerably, so always double check; make sure your Photoshop settings are 'sticking' (just going back and changing a parameter in 'Print Settings' can switch you from 'Photoshop Manages Color' to 'Printer Manages Color' with disastrous results. Always have Black Point Compensation turned on, not doing so will clog up your blacks and shift print contrast.

How Good Does It Get?
How good can you match a print to a screen and vice versa? We have previously set up blind tests in which the subject has to look at a print and change the brightness until the print and screen match. Our findings suggest that inexperienced operators get within ±6% in Lab brightness values but after a few minutes they can achieve ±2% simply because they become more tuned to watching (the values for a 50% grey patch). This is quite close and is certainly as close a call as the photograph's printer might make in terms of preference. For example ±2% is one whole increment in the Advanced Black and White driver and one user might prefer a Normal setting for a print, while another might prefer Dark. Subject to the dangers of the magazine printing press, we show here what this looks like on the reference print.

For the record the tests were conducted using a Fogra Class A certified viewing booth and monitor. The reference print was made so that the mid-tone patch was exactly 50% density on the Lab scale. When tested the subjects were only able to see the print and screen, the colour data was hidden from them. They were not shown the results until the end of the trials.

Expert's Corner
There is a hierarchy of spending on print viewing according to how fanatical you wish to be. We can draw up a table:

In terms of fluorescent tube alone you start at £5.50 for a compact fluorescent 860 and run up to a Phillips TLD 950 at about £11 ex-fittings (2-foot tube) then away to as much as £75 for a certified tube from the likes of Just Normlitch.

Calibrators
The i1 Display Pro should be your opening bid as it validates the calibration afterwards - you really do need to know where you are.

The i1 Photo Pro 2 calibrates monitors, prints, and projectors, and measures light quality. It is limited to RGB profile making and does not contain the industry-standard Fogra/Ugra test for contract proof compliance - for that you need i1Publish at £1,910.

Additionally if you need light testing to ISO 3664 you need software such as BabelColor CT&A at $125. This drives your i1 Pro 2 and provides endless fun for colour geeks!

Lux
No this is not a bar of Unilever soap! It is the measure of 'luminance', which in layman's terms is how bright the light falling on a print actually is. The main barrier to people understanding the meaning of a lux and what it might represent is the fact that it is a logarithmic scale (sound of people diving for cover!). In truth it is not that bad and in most respects is similar to the concept of an f-stop. Thus a change from 140 lux to 1,400 lux is not an apparent, visual increase of 10 times, it's more like four stops of photographic brightness. The fact that the eye can operate in 1/10th lux (moonlight) and also in 100,000 lux (sunshine) is a testament to the quality of the human design and even though it is difficult to imagine a range of one million to one in lux, it is a much more manageable number of f-stops! The best way to grasp the size of a lux is to look at typical values in the table.

LED Lighting Panels
In the McNamee household, Compact Fluorescent Bulbs have a very bad press. They take an age to warm up and remain quite dull even then. They are supposed to outlast tungsten bulbs (ie old-fashioned globes) many times but in reality we find ourselves changing them with equal frequency. The metamerism from them for print viewing is horrendous and we have recorded CRIs as low as 37 on the really cheap and nasty ones from places such as B&Q. They also carry onerous disposal requirements if you follow the letter of the law.

When they first came out LED replacement bulbs we very cold and very directional so much so that they were rejected by senior management of the household for the new kitchen. Today this is changing rapidly and the latest domestic light panels and LED globes we tested are really rather nice!

The Hispec panels are 595x595mm and just 10mm thick. They run off a small transformer to deliver 3,000 lumens at a colour temperature of 4,000K. Our own tests confirmed the CRI as 80+ and the panel delivered a little over 2,000 lux at 1 metre distance. You could easily build the panel into the top of a grey 'box' to form an excellent viewing area even though 4,000K is away from any of the normal standardised viewing temperatures. However, 4,000K is now regarded as the 'office' standard in many places and so you would be viewing at a realistic environment colour temperature for many applications.

At under £50 you can see lots of uses in the photographic studio for lighting applications also. As panels for product lighting they offer interesting possibilities.



Updated 27/04/2026 16:44:22 Last Modified: Monday, 27 April 2026