a fine balance

smartphone colour balance app

Toronto. Modern day smartphone cameras have editors with colour balance and other colour effects built-in. The tiny cameras automatically set the colour balance to white as a starting point so few images need any editing unless the image creator wishes to work on them. Most users of smartphone cameras rarely bother changing the colour balance. The visible light spectrum is listed in degrees kelvin. Visible blue light is 6,000K while the old style incandescent indoor lights were a very warm 2,700K. The actual spectrum band affects the colour too. Some lights have broad spectrum like daylight, others are narrow so they give an odd look to things.

In the early days of transparencies, films and plates were so slow that daylight balance was all that was needed and we rarely even thought of colour balance. In the middle of the last century, transparency film speeds increased enough for both outdoor (sun) and indoor (tungsten) film to be offered. Flash bulbs coated blue could be used indoors with outdoor film. Filters of blue and orange/brown would allow either transparency film to be used under sun or tungsten light. The loss of speed with the orange/brown filter made conversion of tungsten film for outdoor use unpopular.

When colour negative film and colour prints arrived, colour balance was critical. Both paper, and film  had to be corrected during enlargement to avoid any unpleasant colour cast. The worst case was when there was one colour cast in shadows and a different one in highlights. Professionals often used a neutral grey card at the beginning of a film batch since enlarger filters, once adjusted, eliminated any colour casts for the same run of film and paper.

The arrival of digital technology solved colour balance automatically. While we were in transition from film and chemicals to digital cameras and computers, programs like Photoshop could balance out different casts in shadows and highlights. Digital cameras had settings for automatic white balance and for specific lighting. The transition to non-tungsten lighting is well underway. This means that in time all indoor lighting will be much closer to daylight. My overhead light and desk lamp are all ready LED. They use LED bulbs with a broad spectrum reaching a high of about 2,700K overhead and over 3,000K in my desk lamp. The digital camera white balance takes care of any correction needed to emulate the outdoor images.


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