No such thing as black and white

June 01, 2020  •  Leave a Comment

A constant theme in these blogs is about having the right photographic equipment for a professional job, and also,more importantly,  knowing how to use it. The last bit needs to be stressed because in the last twenty years since digital photography stopped being a toy and became a tool, it has become so universally used, hardly anyone takes consideration of what the electronic eye is doing when capturing colour and detail. It’s just somehow assumed that some magical process transforms the information passed through the lens to photo receptors, then sifted through processors, and then finally stored by another predetermined action will produce a completely faithful reproduction of the target image regardless of the circumstances in which it was captured.

The nice bright hi-resolution screens of modern mobile devices disguise the quality of the picture projected. That conundrum generally only raises its head  when we come to put the image into print, when a lot more quality and resolution is required. We know that, but the continuous and repetitive ritual of explaining to a new, or frustratingly even existing customer, that there is no magic wand that will completely turn the proverbial pig’s ear into a silk purse. 

Apart from a blind faith in technology - probably inevitable when we all rely on it so much - it’s a basic lack of understanding that the two mediums, the visual image and the printed one, are made up of entirely different components. 

The best way to compare them is to consider the nature of white and black - the two extremes on the scale of what we see and what a digital histogram will measure in the recorded pixels of an image. In simple terms, white light is the combination of all the colours of the spectrum which we only see when we pass it through a prism or when the sun comes out of an overcast sky producing a rainbow.  Keep that beautiful creation of nature in mind as reference because black isn’t in it. That’s because black in visual terms is the complete absence of light.

We need some light to see anything at all, but we need quite a lot of light to see any colours because we can only see the hue reflected from it by the light that shines on it. In low light conditions everything is a shade of grey, or in artificial light like street lighting for example, an eery yellow.

A digital camera doesn’t have the massive data base of experience that our brains have - at least not yet. It can only take an intelligent guess at what a colour actually is, although you can give it a clue if you are able to provide a reference manually. Otherwise, as most people will chose, the guessing is left to a pre-programmed decision determined by the manufacturer in a factory when the device was made. And however smart the marketing people try and claim  their products are they are still a long way behind the human eye and several hundred thousand years of evolution. They may have improved massively in recent years compared to the early days when people debated whether they would even catch up with film. The average phone now takes pictures comparable wit entry level DSLRs back then. But certain things are just impossible, and one of those is seeing absolute black because it just cannot register a colour that isn’t there.

If you take the matter of colour to an extreme it becomes quite philosophical, like the puzzle of whether if a tree falls in the forest does it make a sound if no one is there to hear it ?  

If we only interpret colour by the light that falls on it, how do we know it has any colour at all. It’s probably a little too far fetched to expect to exchange epistemology wisdom over the shop counter. But it is to the point to consider whether black or white is actually colour. In terms of a computer screen, a completely white screen will have nothing visible on it at all,not even a slight hue,  whereas it will only be really black when it is switched off. What we see as black in an image is purely a simulation made up of the combination of red, green and blue pixels, and is actually a shade of grey albeit a subtle one.

So  in the visual world if white is the combination of all colours and black the complete absence of them, in the print world the formula is entirely opposite. This is the difference between the former which is called additive colour and the latter which is subtractive, where black can be made from the combination of all the other colours of ink.

Because we don’t print white, the base hue is the colour of the paper or other media it is printed on. This is what confuses customers because they can see white, but don’t  understand why it doesn’t always look white when printed, After all they can go to the paint shop and buy a tin of gloss or matt but not appreciate that there is not one but many different shades of what is said to be white, dictated by the hue of the pigments suspended in the liquid.

Paper has the same issue as it is produced from bleached wood pulp and whether it is coated or not, will have a very slight colour hue under any reflected light. Exactly how white it looks will be dictated not just by the colour of the light source shining on it, but by the other colours printed on it as our perception will be adjusted by the comparison of the whole composition. So a dark image will tend to make the white look brighter.

It’s because customers no longer consult a printer as an expert or even an advisor, much as I explained last month they don’t consult a proper photographer. They just create a file and assume it will be absolutely perfect.

Artists can be particularly picky about colours, often only certain colours, some of which are never going to be achieved by four, eight or even twelve colour composite printing. They have the advantage they can go to a craft store and get so many more base colours in oils and acrylic  even before they start mixing them or watering them down. I do know of some printers who virtually refuse to deal with artists for that reason, but I have built up a good reputation by spending a little time talking them through the processes described in this blog.



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