Raw Camera Information.

What is Raw Camera file?
info from - http://www.northlightimages.co.uk/article_pages/why_use_raw.html#what_is_raw

Higher quality digital cameras often have a raw image format available in addition to the normal JPEG and TIFF.

Digital camera image sensors create an image from literally millions of tiny light sensing areas on a silicon chip. The image is built up from individual pixels.

Each light sensor is receptive to a broad range of colors and has a minute colored filter in front of it. There are usually three different colors (red, green and blue). Since we see green best the filters are in a particular pattern (one called a Bayer pattern is common) with more 'green' pixels.

Bayer pattern

The actual sensor can provide data at 12 to 14 bits per pixel (4096 to 16,384 levels of intensity) This is reduced to 8 bits per color in a JPEG file (24 bits total, 8 per color R,G and B). The complete unreduced data is stored in a raw format file.

The camera has a lot of other information available when a picture is taken. Along with the date and time it records shutter speed, aperture and its estimate of the white balance setting and other pertinent data. This is recorded with any picture.

To produce a JPEG or TIFF file, the computer inside the camera has to do quite a lot of calculations on the raw data to produce a picture file. These are carried out once, and the result is what you see when you open the file in a picture editor program. With a raw format file these calculations are not done and all of the original data is saved to the raw file.

How do you use raw files?

Camera manufacturers will provide special software to read and convert raw files. This is in effect using your computer to do the calculations that the camera would have done if you'd saved in JPEG.

Things such as sharpening, color settings and contrast all take place during the conversion. Sadly, most camera manufacturers are much better (it is hoped) at making cameras than writing software for you to use. This is where specialist conversion programs and plug-ins for popular image editing programs come in.

What are the advantages of raw format?

1. All your conversions are done on a fast powerful computer at your convenience.
2. Images can be 'fixed' in ways that would be very difficult without the raw sensor data.
3. You get the full range of data from the sensor.
4. Without sharpening or compression you have not 'lost' any data.
5. You can change your mind about some of the picture settings after you have taken it.

Is there a downside?

1. Raw files are bigger
2. JPEGs are quick and easy to use.
3. Special software is required to do the conversion.
4. Not all cameras support raw formats and may offer reduced functionality when using raw.