Colour Calibration :: Before You Panic II :: Tonal & White Balance

Back in the HSL Luminosity Tint & Shade post, I suggested that luminosity has a big impact on how we judge colour. I also showed how getting a tonal balance in black and white tonal range first, then switching the colour back on can enhance the feeling of colour. There is another important tool to help your colour judgement in a photo and that is White Balance.

The Idea behind white balance is an adjustment to match the colour temperature of your light source, and this is achieve by either warming (usually adding magenta) or cooling (usually adding green) the overall colour rendition. Human vision automatically undertake these changes so we seldom notice the effect of different light sources. However cameras will record these colour cast and that often leads to an unnatural looking image. In the early days of colour film, specific film stocks where developed for different light sources (specifically incandescent and tungsten lights). You needed to use different film under different lights. Digital Photography has enable these adjust to be undereaten in the camera when it prepares the jpeg render of the image. Most DSLR & mirrorless cameras can be White Balance calibrated for given scenes and lighting conditions. RAW formats which record more details of the image and only carry out the white balance (so AWB or Auto White Balance is ok) to render the jpeg thumbnail embedded in the RAW format in camera. However the photographer is able to carry out white balance after the photo is de-mosaiced and re-rendered in postprocessing steps. White Balancing can also be used to remove colour cast created by strong reflections of highly coloured surface.

It is my experience all the software I have used, with a white balance feature, can do a reasonable job removing colour casts providing you pick a neutral grey tone (or White or 18% grey card) in your photo.  As discussed on the video above those packages that let you then copy the white balance adjustment across a number of photos, then let you take a reference image perhaps with a “white balance” card infront or held by your subject. make an adjustment and then copy that across the rest of that set of exposures.

There seems to be quiet a school of thought that you can not perform White Balance on a Jpeg files (including the video above) after it is captured, but my experience is if you have a reference shot of a suitable card (with a white or neutral grey patch) you can improve the reliable rendition of colour. The example below is a jpeg file straight from my Olympus OMD EM10iii camera, which I post processed in Picasa 3 (ie an old bit of software).

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In the example above I have already adjusted the tone to get the the white on my test strip lighter then I used the white balance eyedropper and pointed to one of the two very light grey patches on my test card and clicked. That’s all that’s required. Note I haven’t had to use an expensive bit of specialist gear or customised colour profile.

It is my observation that it requires both Tonal and White Balance together to “clean up” colour in a photo.

HDR on my Phone

The technologies of addressing High Dynamic Range have come a long way in the past decade. Once the process required a couple of specialist programs with round trips through photoshop or similar photo editors. Today there are camera apps for phones that can easily do the job on the phone. I have been using a great little app called HDR Camera+ for a few years now and onto my third android phone. Of the many apps around today it seems to do the most convincing job of creating a “natural” look but expanding the dynamic range. It does take up to three photos, a normal shot one under exposed and the one overexposed. Even when the images are blown out or almost too dark to make out detail, the clever HDR Camera+ software seems to find a reasonable balance. It also does a great job avoiding ghosting when a subject moves.

My new HTC Uplay android phone comes with a built-in camera app that incorporated the HDR feature in the basic camera operations (it clearly takes abit longer that a straight photo but it only takes a second of two to process. There are no tonemapping options (or selection step) but the resulting image is noticeably more balance in high contrast situation. There is even an AutoHDR mode which seems to recognize high contrast situation and switch over to HDR. The image below is an example of AutoHDR.

This camera app software is different from the many HDR style filters (which strive to create the HDR look, normally poorly, and without really boosting the dynamic range). Once you have the higher dynamic range other art filters (like prisma below) can play wonderful games with colour.

 

PhotoFriday :: Architecture

The Contrast of Old & New

For PhotoFriday‘s topic Architecture

Where did the colours go?

onder where the colour has gone? You remember stronger or richer colours and probably the subject was better lit. Some of the many issues that contributes to this disappointment, are exposure (colour get paler and washed out when overexposed or is in very strong light), the light comes from a variety of sources (AWB Automatic White Balance might not be appropriate) strong contrast (which can greatly influence the saturation) harsh light desaturates colour (so many just take photographs in the golden hours after sunrise and before sunset) or the colours in the scene just bring each other down (contrasting/conflicting colours). At the simplest level the human eye can process a greater dynamic range of light than a camera but there is also a lot of psychology associated with colour perception. 

After reading a series of articles about colour harmony by Soraya French in the artist magazine. I realised something very significant. Most artist understand colour as a relative concept. Whereas most of the photographic purists seems to be stuck in a very detail absolute colour calibration obsession. However how we see colour is anything but well calibrated and consistent. 

The outcome is a deep yearning in many photographers for "snappy" colours, because what they have captured doesn't really match what they thought the saw. The issues are partly the materials and equipment but a lot is in the eye of the beholder. If an artist wants a red to look redder he or she will surround it with green (or perhaps a darker cool tone), whereas the photographer grasps at the saturation slider and moves it to the right (often just too far to the right). Perhaps just trying to use the light, within equipment limitations and means of reproduction isn’t enough. Colour is a relative issue we may need to take care of colour mix. just like we need to  compose a photo in the viewfinder, rather than expecting post-processing and perfect calibration to deliver rich colours.

.…Henri Cartier-Bresson wrote in 1975 about this issue

“we do not have yet have the chemical processes that permits the complex breaking down and reconstitution of colour (in the pastel range, for example, the gamut of green is made up of 375 nuances!)”.

Pigments and dyes and the surfaces we can print onto have improved a little since then but we are still looked into the same “constrained” mindset in a lot the digital photographic software and tool. Artist today don’t seem to be so restrained and frequently stray into gorgeous colour schemes without concern for media they are using or the intensity of the colour, but they usually understand the illusion of how the colours work together.

Any talk of colour always brings you to colour theory, (and yes I have spelt colour the correct way), but theory is in my view the wrong word here. What we know as colour theory, the colour wheel, complimentary and harmonious colour schemes is really more a practical guide to mixing colours beginning with primary colours (red, yellow & blue). Trouble is there can be many exception. The knowledge that colour could be both additive (in light) and subtractive (mixing pigments), dates back to Issac Newton but it was the German poet and thinker Goethe that formalised the colour wheel (his wheel in on the right) and introduced the idea that colour had a theory.  This colour wheel web app, is meant for web designers but it is immediately useful to both artist and photographers, the Kuler tool in adobe’s creative creative can now go one step further and pick colours off your photo.

 

Perhaps it is time photographers demanded some better colour tools.

With special thanks of Jessica Hische of Daily Drop Cap for the wonderful start to this post

Out of the Shadows

Kangaroos grazing in the late afternoon sun at the Cardinia Reserve Park picnic area.

Shadows

Contrast

 
These two photos are in fact taken with a few meters of each other, However they do illustrate two very different outcomes facing modern agriculture. On the right is the image of drought and slt being drawn to the surface, The left shows able water but the waterway is being choked with algal and opportunist growth, related to excessive nutrients in the run off.

It never rains but it pours.

Often opposites make an interesting photo pair.

Extended Dynamic Range

  I big issue, largely a secret unknown by most new camera purchases, is that digital cameras have a limited dynamic range compared with film cameras. The problem often leads to washed out highlights (eg often leadfing to the sky will be a bleached white) and no shadow detail (big black areas) which can leave a print from a digital photo looking flat. It is also in past made worse by the cameras light meter which when confronted by with high contrast lighting must choose to what to expose correctly and usually its decision is to try and make an over all "average", which is seldom the right choice. The poor digital photographer has had to choose between correct exposure of the sky or the foreground.

My new camera body, a Pentax 20D, has a feature called Expanded Dynamic Range, which apparently "expands" the light levels expressed by the CMOS Sensor pixles, making it difficult for bright areas to occur in the image. Difficult yes, impossible no, but it has done a good job with strongly backlight pale subjects like these artifical flowers.