A Raw image file isn't actually an image, it's just a data file until it the image data is converted into something more than just 10100011010111101011010101010101010111011111.
Most Raw converters allow parametric editing. Parametric editing does not change any of the original pixles and is also known as non-destructive editing.
Parametric edits are line commands used by the Raw converter in the conversion process. Adobe Camera Raw writes those line commands in to a 'sidecar' .XMP file.
A Raw image data file is indeed 'processed'.
Most digital cameras use an image sensor that
cannot record colors and of course the image sensor is an analog device, not a digital device.
The image sensor has a color filter array in front of it, known as a Bayer Array. The Bayer array is designed so that a 4 pixel square has 2 pixels covered by green filters, 1 pixel covered by a red filter, and 1 pixel covered by a blue pixel, like this;
A 10 MP image sensor would have 2.5 million more of these 4 pixel square color filter arrays in front of it. By the way, they use 2 green color filters because the human eye is most sensitive to green light.
Note that the pixels do not record the color of the filter that is in front of them, but the color of the filter influences the luminosity of the light the pixel records, and the colors in the photo are later inferred by a demosaicing algorithm. Each Raw converter application uses a slightly different demosaicing algorithm to infer the colors, so the various Raw converters all look slight different from each other.
There is another type of image sensor, but it is not used in to many digital cameras. it is called the Foveon image sensor. Instead of a color filter array the Foveon sensor takes advantage of the fact that the color of light effects how deeply it can penetrate a slice of silicon. So a Foveon uses 3 layers of pixels, with each layer of pixels at a different depth in the silicon wafer.
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