Copyright Michael Karbo, Denmark, Europe.

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    Chapter 26. From raw data to RGB

    We have seen how a camera can be set in innumerable ways, so that the image’s colour, sharpness, contrasts, etc. can be adapted to the requirements of the photographer. All these adjustments and adaptations can also take place in image programs such as Photoshop Elements, where photographs can be processed with even more tools.

    Why then are these settings to be found in the cameras? This is the subject for this chapter, where we look closer at the camera’s image computer and the image data it works with. The subject and description are rather technical, so you can easily skip it if it isn’t of interest right now.

    Problems with the colours

    We have earlier seen that a camera can have difficulty fixing white balance. But the setting of white balance is, in fact, only a little part of working with colour.

    Let’s go back to the image sensor. It consists of millions of pixels, each and every one of which is not much more than a kind of primitive light meter. During exposure they register an amount of light, which is converted into a corresponding portion of data. In fact, an image sensor sees the world as an image in black/white and various tones of grey. The individual photocell cannot itself register whether the light is blue or red – it can only register the luminosity of the light. The image data, which the sensor delivers is called raw pixels, and contains information about the luminosity on a grey tone scale from black to white.

    This is why there are a number of tricks and capers involved in creating a good colour photograph. All the work involved in getting from the raw pixels to a good colour photograph takes place in the camera’s image computer, which is an extremely important component.

    Some experts say that over 50% of the image’s quality originates from the image computer’s processing of the raw data.

    A camera takes photographs only in black/white and grey tones. The natural colours are created in the image computer, which is controlled with very advanced software. The image’s distribution of colour, sharpness, contrast, etc. is controlled by the camera’s software, which can be set by the photographer himself via the menu system.

    The natural colours are, in fact, very ”artificial”, as the camera’s image computer creates them. Which is why it is important that they are well constructed and programmed.

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