Inspiring

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Color Adjustments for Photos that will Display under Florescent Lighting

Forum|Forum|3 years ago
September 13, 2022
5 replies
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As a landscape photographer that specilizes in wall murals I often have customers that want their mural to be displayed in rooms with Florescent Lighting. This type of light has a strong green color cast and I am wondering what the best method to set white balance of the printed image to accomidate Florescent Lighting?

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Correct answer johnfr80504

As it turned out, the lighting is 4000K LEDs Thanks for all you input on the topic. We may be able to get a survey by the print company that is going to print the mural.

johnfr80504AuthorCorrect answer

Inspiring

As it turned out, the lighting is 4000K LEDs Thanks for all you input on the topic. We may be able to get a survey by the print company that is going to print the mural.

NB, colourmanagement

Community Expert

Unfortunately, some LED lighting has very poor CRI (color rendering index) so the 4000K may not be enough of a definition.
An icc profile may not be able to compensate. .
For an extreme example think of a red car under those yellow sodium street lamps. It looks grey. No amount of colour change can make it look red.
let's hope those LEDs are ones with a decent CRI.

Some LED is so poor it almost looks like moonlight in its inability to display colours.
good luck

I hope this helps neil barstow,  colourmanagement net :: adobe forum volunteer google me "neil barstow colourmanagement"  for lots of free articles on colour management

TheDigitalDog

Inspiring

And CRI is a pretty poor metric as well.

CRI was developed in large part to aid in the sales of Fluorescent tubes. There are BCRA tiles used to compare under a reference light source but only eight or so. That's too small a set of tiles. That make it easy to create a spectrum that will render the 8-14 tiles and doesn't tell us that the light source is full spectrum. It doesn't tell us how the other colors will render. My understanding is there are two reference sources; Tungsten for warm bulbs and D50 for cool ones: Above and below 4000K. That means that a normal tungsten bulb and perfect daylight both have a CRI of 100! As such, a high CRI is a decent gauge of how well a light will preform in your home but not such a great indicator of how well it will work for photography and proofing. Both a Solux 48 and a "full spectrum" tube from home depot may have a CRI of 97. I can assure you the Home Depot bulb has a giant mercury spike and some spectral dead spots.

A better metric is called CQS (15 very colorful patches). That doesn't tell us about the spectrum which is even a better way to evaluate the illuminant.

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"

c.pfaffenbichler

Community Expert

How long is a mural usually supposed to be on display?

If years or above the aging of the prints themselves could add yet another degree of unpredicability.

Conrad_C

Community Expert

One challenge is that fluorescent lamps come in many variations (cool white? warm white? high CRI?), so if you don’t know exactly what lamps they have installed, you might be guessing wrong. So it is a good idea to try and get more specific info about the room.

As suggested, one way is a technical solution involving measurements of the room lighting, and turning that into a profile you can soft-proof against using the ICC profile of the intended ink/substrate combination. But, you have to have the hardware, software, and some level of expertise, and every part of the capture-to-print chain has to be set correctly for all the numbers to work right.

So the other, much simpler way to do it is…

Acquire advance access to the customer’s installation site, bring a test print made on the intended ink and substrate combination, and view it under the lighting in that room. Indicate corrections as needed, then come back with an updated test print to see if that one is good enough.

Long term, a potential flaw with both methods is that exact color reproduction depends on the specific lamps installed in the fixtures. Less of a problem for museums, bigger problem for general buildings where lighting isn’t tightly controlled. If you get it perfect for the room as it is today, and then a few months later someone calls in a crew to replace some or all of the fluorescent lamps, and the replacement lamps have a different color temperature or spectral response, the photo mural may look slightly different. Or, someday they decide to upgrade the building to LED lighting with a completely different color temperature, CRI, and spectral profile! The lighting might change in the future, outside of your control. But it won’t just be you…it’s been this way for almost every photo mural ever installed, even years before we had precise digital control over print color.

D Fosse

Community Expert

Yes, I was going to mention that: what if they change the tubes or switch to LED.

All things considered I agree with Conrad: Make a test print and adjust to taste. Beyond that - trust the eye's astonishing ability to adapt to ambient light.

Still, a very interesting problem 🙂 If you were to pursue it, it should be possible to print out the standard patches and use, say, an i1 Display Pro to measure. That sensor can be used for "remote" measurement to profile projectors, so there might be a way to tweak and adapt the procedure. The question is what software could produce an icc profile from this.

Kevin Stohlmeyer

Community Expert

An easier way would be to shoot a gray/color card in the venue and use that as a guide for color correction in Photoshop. Record the curves adjustment and apply to your prints.

D Fosse

Community Expert

This is tricky! The eye adapts very effectively to ambient light, and I suspect any attempts at "full correction" will only make it worse. If a white piece of paper still looks white in this lighting, it's probably best to not do anything.

However, the most immediate problem is not overall ambient light color, but uneven and spiky spectral distribution. Fluorescent light is very spiky, and as a result some colors will "disappear" to varying degrees, or appear darker than they should. Others will be more prominent.

This is actually a very parallell situation to camera profiling. This is why you'd make special camera profiles for special lighting, shooting a colorchecker and running it through profiling software (dng profile editor/x-rite etc) to make a camera profile. Fluorescent lighting and LED are prime candidates for this.

Off the top of my head I don't know how you would approach this. I'm sure it's possible, the problem itself is pretty well defined, so I'm sure there are solutions out there.

Michael Bullo

Community Expert

Great answer

Kevin Stohlmeyer

Community Expert

You would have to either take a reading of the light value in the room your images will be shown and adjust accordingly in Photoshop or you can use the Camera Raw filter to adjust your White Balance to Fluorescent.

They would look odd on screen, but when output they would compensate for the lighting.

My only concern is you say it is a green light hue - most fluorescents are magenta, cyan or yellow cast - hence why I would opt to get a color reading or shoot a gray balance card in the room for reference.

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