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The Original is Not Always Right – Weird and Wacky Stuff

Because most photographs include people, neutrals and/or common colours such as blue skies, green grass and sand (of varying colors) special attention is given to the reproduction of those colours in the manufacture of colour film and paper. As a result colours such as chartreuse, lime, pink and orange may not reproduce as accurately. Remember there are only 3 colour dyes within the emulsion (cyan, magenta and yellow) from which to reproduce all the colours within the visible spectrum.

There are also are range of less obvious reasons why a colour may not reproduce accurately. Colour films are sensitive to ultraviolet (UV) radiation. Therefore a fabric reflecting energy, in the form of UV light, will photograph bluer than it looks. If the fabric is blue, little or no problem is evident. If, however, the fabric is of a warm hue (color), that color will be reduced in purity. Because of their low colour saturation neutral, or near neutral colours, are the most susceptible to this problem. The black of a groom’s suit or the near white of a brides dress, photographed under bluish color light, may display this color caste to a greater degree than the rest of the scene.

In the case of ultraviolet fluorescence some fabrics absorb ultraviolet radiation and re-emit it in the near blue portion of the visible spectrum. As our eyes are not very sensitive to this part of the spectrum, the effect may not be evident until viewing the final photographic image.

Many white fabrics contain artificial brighteners, added during manufacture or laundering, to give them a brighter, more visually white appearance. Unfortunately this phenomenon can cause near white wedding dresses to photograph with a very distinct bluish color cast. This effect is virtually impossible to correct with conventional printing methods. Examination of the fabric, under an ultraviolet light source, may indicate whether or not a fluorescence problem is likely to be encountered. If so, a filter placed over the less will not adequately fix the problem. Prior to digital imaging a strong ultraviolet absorbing filter, such as a gelatin Kodak SB Wratten filter, placed in front of the light source (flash/strobe) would often reduce the problem. Fortunately RAW converters and Photoshop offer a variety of ways to adjust the image and produce an acceptable result.

A particular type of colour reproduction problem, referred to as anomalous reflectance, is likely to cause the most trouble for the unwitting photographer. They exist at the far-red and infrared end of the visible spectrum, where the eye has little or no sensitivity. Flowers, such as the heavenly blue morning glory and the ageratum are examples of subjects from the natural world that can lead photographers a merry dance indeed. They reflect, in addition to the blue light that we see, a lot of deep red light. The fact that colour films are more sensitive to far-red sensitive end of the spectrum than the human eye causes the flowers to reproduce with a more mauve or pink colour than we would expect.

While the use of a filter, such as a Kodak Wratten 82B Color Conversion filter or Kodak Wratten CC30B Color Compensation filter, may reproduce the flower closer to our expectations, it will distort any other colours in the scene. When making traditional prints in the darkroom, or on the desktop, a range of approaches can be make to selectively alter the colour of the flower without any adverse effects on surrounding colours. In the case of the darkroom print, the flower will need to be dodged during the original exposure and then burnt in with an adjusted filter pack, which effectively changes the color of the light emitted from the enlarger, to produce a more acceptable color.

Due to their relatively inexpensive price and easy integration into synthetic material a range of organic dyes became popular with fabric manufacturers and were included into various types of furniture, drapes and the like. These organic dyes produce high reflectance in the far end of the visible spectrum. In the case of medium to dark green fabrics, the far-red reflectance tends to neutralise the color of the green fabric in photographs. In some cases the green fabric can even reproduce as a warm hue. In the ‘old days’ this provided commercial photographers, particularly those who didn’t shoot Polaroids, with a nasty surprise when they picked up their images. Naturally they’d blame the lab. In many cases the lab would blame the manufacturer (e.g. Kodak, Fuji or Agfa). The reality was that photographic film was designed to photograph naturally occurring, real life colors, rather the effects organic dyes might have on certain colors of synthetic material.

Film used might consider utilizing a Kodak Wratten 70 filter to identify high reflectance at the far end of the spectrum.  Interestingly, close inspection of the fabric, under a tungsten light, will cause a green natural-fibre material to appear black. Conversely, a green synthetic material, displaying high reflectance in the far-red, would appear much lighter.

Because judgement is quantitative, it’s a good idea to retain a sample of a green fabric known to reproduce well, as the control item, for such tests. If a fabric of similar hue appears distinctly lighter, in a side-by-side comparison through the Kodak Wratten 70 filter, a colour reproduction problem can be expected.

Of course it’s always a good idea to run tests under the same or similar conditions (subject, scene brightness range, lighting, colour temperature) to what you would expect to experience when actually photographing the specific fabric or job in question. That way nasty surprises are reduced and deadlines met. These days’ digital shooters experiencing color reproduction problems could simply contact the manufacturer and request specific data to describe the exact color of the fabric in question. They would then select the problem area of the product (e.g. couch) within Photoshop, to separate it from its surroundings, and change the color of that area to match the data supplied from the manufacturer.

 

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Glenn Guy, Blue Sky Photography

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