Good consistent print lighting is just as important as a well-calibrated monitor.  In fact, the two go hand in hand.  When you are calibrating your monitor, what you should be doing is setting your screen to match the brightness and color of the lights in your workspace.

There are four main factors to consider when choosing the lights for your workspace.  We will talk about each of these in more depth below. 

• Brightness: Are your lights bright enough to match your monitor and to show adequate detail in your prints?  Dim/moody lighting may create a comfortable atmosphere, but you will lose much of the detail in your printed work.
• Color: The Color Temperature value of your lights indicates how warm or cool they are.  Extremely warm or cool bulbs can be very problematic in print evaluation.  Ideally, you should calibrate your monitor to the same color temperature as your lights.
• Quality: The Color Rendering Index rating of your lights determines how accurately they will render the colors of your prints.  The higher the CRI rating, the more accurately your lighting will render colors.  
• Consistency: How consistent is the lighting that you are viewing your prints under?  Do you have a lot of windows in your workspace?  If so, the brightness and color of your environment could change throughout the day.  Thus, a print that matches your screen on a bright sunny day may not match at night.

The Brightness of Your Lights

One of the most common concerns that we hear from clients is issues with dark prints.  The primary factor in this issue is a mismatch between the brightness of the monitor and the brightness of the ambient lighting.  Obviously, not everyone wants their home or office lit up like a museum or gallery, but having some sort of dedicated lighting for viewing your prints is a good way to verify your print looks correct and can be invaluable to your image editing process.  This could be as simple as having a table lamp with a good bright bulb that you only use specifically for print viewing.  There are also lighting options specifically designed for print proofing (see Lighting Solutions below).  Whatever route you choose, as long as you are creating a good bright lighting situation you should be successful.  

The Color of Your Lights

Just as important as the brightness of your lights is their color.  Light bulbs are rated in terms of Calculated Color Temperature or CCT.  This is a measure of how warm (yellow/red) or cool (blue/cyan) the light produced by a bulb is.  This rating is measured in Degrees Kelvin (K).  As an example, an average incandescent light bulb will typically have a CCT of around 2000K.  A “Warm White” LED or Fluorescent bulb might be in the 3000K to 4000K range.  A “Cool White” bulb might be in the 5000K to 6500K range.  Different manufacturers may give different names to the various colors of their lights, so it is best to check for the actual color temperature value.

Typically, it is advisable to stay within the middle range for color temperature of your lights to avoid overwhelming color casts when viewing your prints.  The most important factor though is making sure that your monitor is calibrated to the same color temperature as your print viewing lights.  So, if your lights are 4000K, you should calibrate your screen to 4000K. See Monitor Calibration for more on setting a proper white point for your monitor.

We highly recommend a workspace lighting temperature of 5000K.  5000K, also known as D50, is a print industry standard temperature for printer calibration and print evaluation and is the color standard to which we at Bay Photo profile all our printers. This is certainly not required, though.  If you prefer warmer or cooler lighting in your workspace, you can still achieve a good screen-to-print match with other color temperatures. 

The Quality of Your Lights

Not all light bulbs are created the same, and different types of light bulbs (LED vs fluorescent vs incandescent) will render colors differently.  Even within the same type of bulb, there can be very different levels of quality.

In addition to Color Temperature, light bulbs are rated in terms of the accuracy with which they display colors.  A bulb’s Color Rendering Index rating, or CRI, measures how accurately a light source displays the colors of objects as compared to natural sunlight. It's a scale ranging from 0 to 100, where 100 represents perfect color accuracy, matching the color of objects under natural daylight. A higher CRI indicates better color rendering, meaning colors appear more true to life.  A lower CRI indicates poorer color rendering, resulting in distorted and inaccurate colors.

CRI values:

• High CRI (90+): Excellent color rendering; colors appear true to life. 
• Good CRI (80-90): Satisfactory color rendering; color will only be slightly altered.
• OK CRI (70-80): Common lighting; colors will be noticeably dull and distorted.

• Low CRI (under 70): Poor color rendering; colors will appear very dull and distorted.

   

The CRI value of your lights could have a significant impact on how accurate the colors of your prints appear.  It is advisable to invest in the highest CRI bulbs that you can afford.  Different types of bulbs have a range of available CRI ratings.  For example, common consumer grade fluorescent lights typically have a CRI of 50-70, but some companies do sell High CRI fluorescent bulbs (CRI 90+) for a higher cost.  Same for LED bulbs, most LEDs have a CRI of 70-80, but LEDs of up to 95 CRI are available.  Traditional incandescent light bulbs (your classic tungsten filament bulbs) have a perfect CRI of 100, however their extremely warm color temperatures (typically around 2000K) can make them unsuitable for color proofing.

Consistency

The consistency of your lighting can be one of the subtlest and hardest to manage issues.  As mentioned earlier, natural light in your workspace can be difficult to manage.  Natural light changes significantly in terms of brightness and color temperature throughout the day.  

Natural daylight spans a broad range of color temperatures.  Sunlight at noon is typically around 5000K, but an overcast day or in a shadowed area, color temp that can be significantly cooler, around 7000K or higher.  Around sunrise and sunset, the color temperature can become significantly warmer, around 3000K.

But not everyone wants to work in a windowless room in order to maintain perfect control of their ambient lighting.  But finding ways to mitigate any changing light can significantly improve your ability to edit your files accurately and predict the brightness and color of your final prints.

Things like neutral-colored curtains or blinds can help maintain that consistency without adding a significant color cast to your area.   Walls or partitions can also help limit the impact of inconsistent lighting.  

Lighting Examples

Below is an example of good print lighting setup:

...and here is an example of a problematic print eval setup:

Lighting Solution Ideas

There are a few companies that offer dedicated lighting specifically designed for print proofing.  Please note that these are not, in any way, paid or sponsored endorsements.

GTI Graphic Technology Inc: GTI offers dozens of different proofing solutions ranging from tabletop proofing viewers to full booths and overhead lighting fixtures.  These tend to be expensive, but they are at the forefront of print proofing technology.

Calibrite Grafilite: This desktop print proofing lamp has excellent color accuracy (CRI 95) and features variable color temperature and brightness settings.

Key Lights are another cheaper option.  These LED panels are primarily designed for studio use, but they are very useful for print evaluation as well.  Options like the Sokani P25 Key Light have a high color reproduction rating (CRI 95), variable brightness and variable color temperature.  There are many brands and models available from online retailers, just make sure you confirm the CRI value (90+ is recommended) is listed in the description.  

And finally, many light bulb manufacturers do produce high CRI versions of typical consumer style light bulbs that can be installed in a standard lamp or fixture.  Companies like Waveform Lighting, Phillips, and many others offer numerous high CRI options.