colour correction for iphone

Of course, one of the reasons (but by far not the only one) that the iphone has been so successful is the quality of the camera that is built in. It was certainly one of the features that made me switch from Nokia about 3 years ago after more than 15 years of loyalty to the swedish brand. So I was interested to read recently that the next iphone may feature advanced colour correction methods and promises to be even better than its predecessors. You can read about the story here.

Colour correction is necessary because different cameras use different RGB primaries and because the activation of the RGB sensors when taking an image depend upon the quantity and quality of the ambient illumination. So, for example, imagine the light was very very red, then the R channel of the camera would be more strongly activated than if the light was whiter. However, our visual systems are able to compensate for this so that most of the time we don’t notice objects changing colour when we move from one room to another or from inside to outside. Colour correction is inspired by human colour constancy and attempt to correct the images so that the objects in the scene would retain their daylight appearance. However, colour correction is difficult; that is, it is very difficult to get it right all of the time. One frustration I have is taking a photo of my band (I play drums in a covers band) under very colourful lighting. Often the images are very disappointing and lack the intensity of the original scene. That is because, human colour constancy is only partial and under extreme lighting things really do change colour markedly – such as under our intense LED stage lighting. In these cases I think sometimes the automatic colour correction is actually too much and I have found that I have to modify the images I capture on my mac to try to recreate what I think the original scene looked like. So auto colour correction – the state of the art – is certainly not perfect. Let’s hope this story about an advance made by Apple is true.

what is it like to be colour blind?

Another simulator on the market that shows you what your image or website would look like to someone who is colour blind. This one is from a company called ETRE – for further details see http://www.etre.com/tools/colourblindsimulator/

In the image series below the left image is normal and the ones in the middle and right show protonopia and deuteranopia respectively.

For more on colour blindness see my earlier post.

Race for colour

The films were made by a young British photographer and inventor called Edward Turner, a pioneer who can now lay claim to being the father of moving colour film, well before the pioneers of Technicolor.

The footage will be shown to the public from 13 September at the museum in Bradford. And a BBC documentary, The Race for Colour, will be broadcast on 17 September in the Yorkshire and south-east regions on BBC1. I will feature in the film for a minute or two. Exciting.

For further details see the story in the Guardian.

measuring skin colour

I came across an article in the Daily Mail about a phone app that can be used to measure skin colour. It is produced by Fujitsu. Trying to measure colour using a digital camera is difficult. The RGB values you obtain depend upon the lighting and the settings of the camera and even on the make of the camera. Technically, we say that the RGB values are device-dependent. Fujitsu have got around this by using a mask (see picture) that contains some standard colours that are skin tones. Presumably the app grabs the RGB values of the standard colours and then uses these to make an adjustment to the captured RGB values of the actual skin. It’s very clever and I am impressed.

homemade colour measurement

Interesting article about a guy who built his own colour-measurement device at home from simple components.

colour kindle

I recently used a Kindle for the first time. I have never had much interest in them; since a smart phone or a tablet seem to do everything that a Kindle does and a whole lot more. However, there is one advantage of the Kindle and that is that the screen is easier to read the brighter the ambient illumination. So on holiday, for example, the Kindle really comes into its own if you want to read novels on your sun lounger. Nevertheless, it is a major limitation that the screen is only black and white. For reading novels I guess its ok; but for lots of other reading material I think colour would enrich the experience. It had been thought that a colour kindle was many years away. But today I read a report on CNET that claims that Amazon is set to launch a colour e-reader later this year. There are doubts about whether the technology is ready yet … we’ll see.

traffic lights for everyone

About 8% of men are colour blind. In the past I have written about how designers may not adequately take this into account effectively ignoring 4% of the population. I also wrote about how in Korea the problem of traffic lights for colour blind people was being addressed by using different shapes for the different colours.

Now I am interested to hear about a development from Japan – Professor Ochiai at Kyushu Sangyo University has developed a clever modification that is not noticed by people with normal colour vision but helps those who are colour blind. Before the introduction of LED lights people often could tell red from green by the difference in brightness. But LED lights are so bright that they look rather similar in brightness, and for someone with red-green colour blindness they may look identical. Professor Ochiai has added a blue cross to the red light which is very visible to colour-blind observers but can hardly be noticed by the rest of us. Very clever!!

The new lights are being tested in Fukuoka and are due to go on test in Tokyo soon.

changing eye colour

On my way to CIC – my favourite colour conference – http://www.imaging.org/IST/conferences/cic/.

A six hour lay-over in Chicago so no excuse not to make a few posts. The first interesting bit of news I just came across is a story in the BBC about a doctor who seems to have developed a laser technique to change eye colour.

Apparently 20 secs of laser treatment can remove the pigment in eyes so that brown eyes become blue. You can read more about the story here. Don’t try this at home though – they are still conducting safety tests and some experts think the treatment could lead to other health problems.

Gjøvik Color Imaging Symposium

A quick reminder that registration for the Gjøvik Color Imaging Symposium is still open. This is a tremendous colour conference and Gjøvik in Norway is a beautiful place to visit. Further details can be seen at http://www.colorlab.no/events/gcis11/program.

colour management for beginners

Colour displays are now affordable and enjoyed by consumers at work, at home, on mobile displays and in cinemas. Consumers often take it for granted that there is good colour fidelity as images are transferred between different devices. So, for example, a red object in an image appears to be approximately the same red when the image is displayed on different computer displays, when it is printed, and when it is viewed on a mobile phone.

This colour fidelity is not easy to achieve. Different devices use very different technology to display colour images. For example, a computer display will mix together light from three primaries (red, green and blue) to generate a range (gamut) of colours. On the other hand, a printer uses completely different technology and typically uses mixtures of cyan, magenta, yellow and black inks to create the gamut of colours. Even computer monitors use a variety of different technologies (from CRT displays, which are becoming obsolete, to LCD, LED, and plasma technologies) each of which may use quite different red, green and blue primaries. Colour management is required to compensate for differences between the technologies (colour primaries, colour mixing, colour gamuts) between different image-display devices. This necessitates that the companies that produce image-display devices must cooperate so that the devices are able to talk to each other; this is achieved through the International Color Consortium (ICC) . The ICC is an industry consortium that was established in 1993 by eight industry vendors (including Microsoft and Apple). Today approximately 70 companies are members of the ICC whose goals are to “create, promote and encourage evolution of an open, vendor-neutral, cross-platform colour management system architecture and components”. The ICC system is implemented in terms of device profiles and colour management system. The device profile is a computer file that is associated with each device (printer, camera, monitor, etc.) that essentially contains information to allow colour to be managed. In the case of a computer monitor, for example, the device profile would include information about the monitor’s primaries that would allow the colour image to be adjusted to compensate for the properties of the monitor so that the colours are displayed correctly. The colour management system is software that manages how these device profiles interact with each other and is normally part of the operating system of the computer.

Thus, when users capture, view, or print images they are using colour management all the time even though they may be unaware of it. Though this level of colour management is built into software and device drivers and is broadly invisible to the user it does enable colour consistency for images when they are captured, viewed and printed throughout the world. However, this level of default colour management is far from perfect. It does not, for example, generally account for changes in settings for a device (for example, a user may change the contrast, brightness, or colour temperature of a display) so that colour fidelity is, in practice, only approximate. This level of colour fidelity is probably sufficient to satisfy about 90% or more of consumers for whom colour is not a critical issue. However, for professionals working in industries where colour is a major concern (e.g. design, retailing) a higher level of colour management is often required. For these users, it is possible to obtain systems (typically low-cost colour-measurement devices and associated software) that allow a user-defined profile to be generated for a particular device with particular settings. This user-defined profile then over-rides the default profile and should enable a better level of colour fidelity to be achieved. Nevertheless, colour fidelity is always likely to be an imperfect issue. It is difficult for colour-management systems to perfectly compensate for the fact that, for example, different devices may generate quite different colour gamuts (typically, the bright red on a computer screen cannot be achieved by a CMYK consumer-level printer).

For ICC see http://www.color.org