Tag Archives: Colour Temperature

Avoid funny colour casts in your holiday pictures

Posted on July 20, 2013 by Damon (Editor) | Comments Off

White balance – grey card

Unnatural indoor colours?

Holiday time – out comes the camera and most daytime shots are great. However, indoor shots often get a funny colour cast. Odd yellowish, greenish or blue tones have appeared. The reason? Auto-white balance problems. The condition is curable.

Auto-white balance problems

Outdoors the auto white-balance function works reasonably well. But not in all cases. Auto-white balance aims to iron out colour casts in your photography. The problem is that the camera frequently gets it wrong. There are two main places that can happen…

Out of doors when there is a lot of one particular colour around (eg. lots of sky blue; orange/red sunsets or snow)
Indoors when there are artificial lights illuminating the scene (ordinary domestic lights, fluorescents and bulbs).

When a lot of one colour appears in your shot. The camera assumes that too much of one colour is a problem. So, it shifts something called the colour temperature toward a neutral grey colour. This takes out the colour cast.

Intentions ruined

If you intended to capture that colour cast (from a sunset for example), the auto-white balance mechanism will ruin your shot. Typically blue skies and white snow tend toward grey. And, the real classic, lovely orange and red sunsets look pink, cartoon-like and flat instead of saturated. Orange and reds are particularly badly affected. So if your sunsets look cartoon pink/grey instead of saturated fire-orange you need to adjust your auto-white balance.

• Auto white-balance fail! •

Cartoony pink-grey skies. The auto-white-balance function has colour shifted the orange/red tones toward greys.
Click image to view large
• Auto-white-balance fail! • By Netkonnexion on Flickr

Artificial light also creates a colour cast. Often the auto-white balance cannot properly adjust for this. The result is odd yellowish, blue or greenish tones in the picture where you did not see them yourself at the time. These also require an adjustment to your white-balance.

Why is there a problem?

Mainly the problem arises because we have made an adjustment in our heads without noticing. Most of the time we compensate for these colour casts and don’t see them. In fact, once we realise there is such a thing as a colour cast we can train ourselves to see it. We certainly see the heavy red colour casts of evening and early morning light. If we look carefully we can also see the yellows and blues from domestic lights – although less strongly.

Remedies

There are two possible ways to tackle the situation…

Compensate for colour casts by using a camera pre-set.
Correctly set the white-balance so it records the natural colours.

DSLRs have reasonably good pre-sets to tackle well known colour cast issues. On most cameras you will find white balance settings something like these below. The notes explain details…

Auto – The cameras best-guess colour match for what it senses. OK most of the time. Poor when there is a predominance of a strong colour.
Tungsten – (bulb icon) indoor, tungsten incandescent lighting using bulbs. Cools the colours – often bluish. This setting helps remove blues to warmer tones.
Fluorescent – for use under fluorescent lights – will tend to warm up the colours.
Daylight/Sunny – (sun icon) indicates the ‘normal’ white balance (may not be present if this is the default setting).
Cloudy – (cloud icon) Adds a warmer, yellowish colouration.
Shade – This light is cooler (bluer) than sunlight. Shade mode warms the colours a small amount.
Flash – (lightening icon) Stark and cool, flash desaturates towards blue. Flash setting compensates with a slightly warmer yellowish tone.
Custom – You do a little procedure to get an accurate setting to suit the situation.

Accurate colours

Colour accuracy is important. You really do want a bright blue sky or white snow or saturated red sunsets. The problem is that the pre-sets are averaged out for the “types” of situations encountered. The pre-sets will change the colours from dull flat colours to more representative ones. For example more saturated sunsets will be captured if you use the cloudy setting. However, to get it right you need to adjust the custom white balance.

Setting the custom white balance is simple. The camera does most of it. You need a “neutral grey card”. This is simply a card or piece of material set at an average grey colour, normally at 12% grey, which matches the cameras accurate shade for neutral. You can buy these quite cheaply at most camera stores. (See: Range of photographic grey cards).

• The Lastolite Ezybalance •

collapsible; durable
wipe clean; very light
12% grey; 30cm wide

An easy to use grey-card system. White on one side, grey on the other. The card doesn’t crease, the sprung border stretches the material tight. The card collapses into the supplied case, slipping easily into your camera bag. A great accessory to ensure colour accuracy in your pictures. You should not be without one.

To set custom white-balance

It’s easy to set the white balance. However, there are lots of variations for how different cameras do it. Therefore it’s essential to use the right procedure from your manual. To get ready…

Place the card about 30cm/12 inches in front of your camera.
Zoom in or out to make the grey card fill the frame.
Now follow the camera manual “custom white balance” instructions.

To ensure complete accuracy you must do this procedure in the ambient light in which you will be shooting. This is the light the camera will sense and compare to the grey on the card.

More after this…

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Shooting with RAW vs. *.jpg

I am sure lots of you are saying, “But I shoot with RAW and this is unnecessary”. OK, that is partly true. You can, with RAW format files change the white balance in the post-processing. Here are two reasons you should NOT do that…

It is time saving to get as much right in the camera as possible. I like to spend my time shooting not computing!
I have rarely met anyone who can remember colours so accurately that they get the post-processing colour and temperature balance right. I like to get them right in-camera as accurately as possible. Then I can safely change them later if necessary.

RAW format is excellent – you have complete control over colour temperature and hues. However, if the picture is wrong from the start, RAW is only as good as your own memory or colour awareness. Artists of many years may be able to remember colours accurately. Very few others can. Beginners especially have very poor colour memory/accuracy. So, use RAW, get it right in-camera – then do your artistic processing from a solid colour-base you know is accurate.

Compensation and accuracy

While both compensation for colour casts, and accurate representation of colour casts both rely on white balance there are differences in how they are treated. Strong colours or a strong colour bias through the picture needs some special treatment. Think about the two different methods above and practice them.

Comments, additions, amendments or ideas on this article? Contact Us
or why not leave a comment at the bottom of the page…

By Damon Guy (author and Photokonnexion editor)

Damon Guy (Netkonnexion)

Damon is a writer-photog and editor of this site. He has run some major websites, a computing department and a digital image library. He started out as a trained teacher and now runs training for digital photographers.
See also: Editors ‘Bio’.

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Posted in Camera control, Composition, How to..., Light and Lighting, Photography, Shooting specific subjects, Things to try, Tips Tutorials & Techniques

Tagged Ambient light, Blue, color, Colour, Colour shift, Colour Temperature, Compensation, Grey, Greyness, Holiday, JPEG, jpg, Orange, RAW, Red, Saturation, Sunrise, Sunset, White balance

Thinking about colour

Posted on February 19, 2013 by Damon (Editor) | Comments Off

What do we really see? Do you and I see red the same?

Can you and I agree on colour?

Do you and I see the same colour when we look at a red object? We may be seeing completely different hues, or tones. There is no way to objectify colour. We see it, have have name for it, but we cannot agree that we see exactly the same thing. What we see is an internal experience and we cannot share it with other people.

White balance

When we see a photograph taken under the influence of a tungsten or fluorescent light we can clearly see the colour casts. Modern DSLRs have standard white balance settings to neutralise these colours as they are so common. What about colour casts that are not so common? Well, in that case we need to set up a custom white balance setting.

The problem is, we do not have an objective measurement of colour that means the same to everyone. However, if we can standardise colour against something, then we would have a way of sharing a colour on a fixed basis. You may see a slightly or very different colour to me. But when you do, if it is standardised, it does not matter. That’s because we can both agree on it against the same standard.

Light which may appear white to the eye is not necessarily an even distribution of colours. The visible colour spectrum contains a combination of colours which together form white. The various colour temperatures in that mix are manifest at the different colour wavelengths. In photography we use a neutral grey (18% grey) as a calibration point that represents the 50% point in the eyes’ contrast range between brilliant white and perfect black. We can use this grey level to allows us to neutralise colour casts generated by sources which are not on the white light spectrum.

How do we neutralise these colour casts using 18% grey? Well, if certain scenes are slightly off colour or we are unable to create a clean white in a white environment there is probably a colour cast or the camera is compensating for too much brightness. For example, it’s common to have grey snow if the camera overcompensates for brightness in the whites. If we calibrate the camera for a custom white balance we can set white settings to be true to the scene in which the grey card is used. To establish the calibration point we photograph the 18% grey card within the light that contains the colour cast. Then we set the 18% grey point to be correctly grey (18%) and this will even out the colour cast. Check your manual for the exact procedure for your camera model.

Of course this assumes that the manufactures got the colour range-calibration correct. However, there is good evidence that we all agree the calibration points produce consistent colour results. So, if we calibrate the camera to the 18% grey card in the ambient light (with colour cast) the same camera colour range will shift from the colour cast to make the camera see the card as 18% grey again. The adjusted colour is a custom white balance – but it adjusts the colours to be consistent with the grey card standard.

Is Your Red The Same as My Red?

In the video we see that it is difficult to agree on the colour match between people. The video shows how different people can see a colour in a unique way but still agree on the existence of the colour even though our experience of it can differ. However, in reality we can only behave as if we agree that colours are the same. We do not have actual knowledge they are same to everyone. Hmmm! Mind bending… but worth thinking about

Vsauce

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Posted in Camera control, Equipment, Light and Lighting, Tips Tutorials & Techniques, Video included

Tagged Camera, Colour, Colour cast, Colour Temperature, Colours, Light, light and lighting, Video, White balance

Six things to know about light

Posted on August 22, 2012 by Damon (Editor) | 3 comments

‘Let there be light’ – Lighting is something every photographer has to work with

Sometimes we cannot see bad light.

Our eyes compensate for the lighting in almost every indoor situation. We barely notice the colour of light. Unfortunately, our shots sometimes come out burdened with odd colours. Find out more…

Colour Casts

Almost every light source has its own colour. If the ambient light in a place is affected by the colour of the light our eyes ‘adjust’ that colour to white. When we take a picture with a camera it does not adjust, it faithfully reproduces it. Then, when we look at the picture, we see something called a ‘colour cast’. This is an odd overall colour in the picture. It’s caused by the colour cast affecting the colour tone of everything in the influence of the light. Normally, to get rid of the cast, we adjust our camera to this colour cast as white light – much as our eyes adjust. This is called ‘adjusting the white balance’. The light in the picture will look more like daylight again. We might not want to do that if the picture had the colour cast from, say a party, where the colours may be atmospheric. For many ordinary pictures that is not true and the artificial lights simply make the picture look odd.

Light Sources

Light sources are a range of things that produce light. Sources of light like bulbs or fires have very different origins and temperature, therefore the colour they produce is unique too. In photography our lights can strongly affect the outcome of our pictures. That is especially true if the light source has a colour cast. Photographer’s use of artificial light sources, like camera flash, studio lights and other photographic sources, needs care. Any old light will not do the job. We need to reliably create light without a colour cast. When manufacturers make light sources for photography they try to ensure that the light they create is ‘Daylight balanced’. Which means the light that is emitted by that source is a close colour-match to daylight or some other stated standard. Of course the colour of daylight varies – the colour of dawn and dusk is very different to a sunny mid-day or a rainy afternoon. Those colour differences are because of the affect that the atmosphere has on the light from the Sun. In fact, the Sun has a well known colour. So do other light sources.

Colour Temperature

The colour of a light source is a result of its ‘colour temperature’. The ‘colour temperature’ of a light is measured in temperature units called Kelvins, after the famous physicist Lord Kelvin. Kelvins are usually designated with a capital K – so we say 5,000K meaning five thousand Kelvins. The measure of Kelvins is important to photographers because the colour of the light needs to be defined.

By way of example it helps to think how an iron bar heats up. If we put iron in burning coals it gradually changes colour as it heats. First, it goes a very dull reddish colour. More heat and it goes bright red. As it heats more it gets orangey, then yellow. Next it turns slightly green then on to white – the hottest heat. The colours given off define the colour temperatures.

Our language confuses things. Sitting around the camp fire we are ‘warm’. As a result we think of our day to day ‘warm’ colours as reds. But actually they are cool colours on the Kelvin scale. Compared to the temperature of the Sun they are very cool! The Kelvin scale gives us the colour temperature indicators. The lower the Kelvin colour temperature, the more yellow to red the light. Higher colour temperatures is the bluer-to-white light range.

If we know the colour of light it helps us to describe it. For example:

Reds/yellows (2,700K to about 4,000K – Cool Kelvin scale colours)
Moonlight (4,100–4,150 K)
Sunlight overhead; electronic flash (5,500 K to 6,000 K)
Overcast daylight (6500 K)
Bluish/white (higher than 6,000K to 27,000K).

The colour temperature relates to the colour of a thermal light source. However, other light sources (eg. chemical or fluorescent) may have a colour on the colour temperature scale. They do not necessarily have an actual thermal temperature to match. So the colours are indicative and not actual temperatures. You might therefore burn yourself on a tungsten filament bulb – a thermal source. You might not burn yourself on a low-energy soft fluorescent bulb as the process for creating the light is not thermal. However, the colour the light produces can still be seen on the colour temperature scale. See a colour chart of colour temperature examples.

Incandescent bulbs

A light bulb with a filament creates light by the electricity heating the filament until it emits radiation. It’s a thermal source. Incandescent bulbs are really very inefficient. Only about 10% of their light is visible. Incandescent bulbs can create a strong colour cast. If you are shooting on auto-settings (and using *.jpg files) make sure you check any shot you take under such a bulb.

If you find you have an odd colour then you will need to adjust the white balance of the camera to get rid of the colour. Normally digital cameras have an easy menu setting for white balance. You may see it marked as a light bulb icon. Alternatively it may be called ‘Tungsten’. The latter is a metal often used in the filament of bulbs. The setting should compensate for your colour cast. Some bulbs may vary. So test by ‘chimping’ to get it right. Check your cameras manual to find out how to adjust the white balance setting. You should do it when you shoot, as you will not be able to adjust it later (unless you are shooting in a RAW file format).

Fluorescent lights

Strip lighting, or fluorescent tubes and modern low energy bulbs all produce a colour cast (unless daylight adjusted when manufactured). As with the light created by bulbs with filaments, you can adjust for it in your camera. There is generally a tube icon or a fluorescent setting in the white balance menu. Consider the light you are working with carefully. Not all fluorescent lights have the same colour and some settings on your camera may not be quite right for your setting. So be prepared to experiment.

The vocabulary of light

There are literally hundreds of words that describe light, its colours and various conditions and states. It helps to have a good vocabulary of light as you may find it easier to read about light and talk to others if you know the right terms. We have compiled a list of some of the most significant to photographers. We are also adding to it… So let us know if there are terms that you think should be in the list! You can find our ‘Light’ word list here.

Kelvin

Black body radiator

Definition: Post-Production; Processing; Post-Processing; Image Editor; Editor

By Damon Guy (author and Photokonnexion editor)

Damon Guy (Netkonnexion)

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Posted in Background Info., Insights, Light and Lighting, Starters School

Tagged Color Temperature, Colour Temperature, Fluorescent, jpg, Light, RAW, Tungsten, Vocabulary

Tag Archives: Colour Temperature

Avoid funny colour casts in your holiday pictures

Unnatural indoor colours?

Auto-white balance problems

Intentions ruined

Why is there a problem?

Remedies

Accurate colours

To set custom white-balance

Shooting with RAW vs. *.jpg

Compensation and accuracy

By Damon Guy (author and Photokonnexion editor)

Thinking about colour

Can you and I agree on colour?

White balance

Is Your Red The Same as My Red?

Six things to know about light

Sometimes we cannot see bad light.

Colour Casts

Light Sources

Colour Temperature

Incandescent bulbs

Fluorescent lights

The vocabulary of light

By Damon Guy (author and Photokonnexion editor)

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