What is a RAW file (CR2, NEF, …) and why it’s not a photo !

Source: Internet - on 11-Dec-2019

The first step in taking a digital photo is to expose the camera’s photo-sensitive chip to light.

On that chip are millions of units called pixels which transform the amount of light each receives into a voltage level expressed as a digital value.

These values are saved into a file called RAW, meaning “unprocessed”. RAW file formats and their extensions vary by camera manufacturer eg NEF for Nikon, CR2 for Canon, ARW for Sony, etc …

Depending on cameras, that RAW (along with META DATA eg the date the photo was taken, ...) is saved and / or converted (to JPG in the camera, and to a JPG or to another format on a computer) in order to display it. Only then do you have a photo that you can examine: a RAW file is not a photo!

The conversion from RAW to a photo format depends on each camera and software maker, with different sets of assumptions for white balance, contrast optimization, color saturation, noise reduction, ...etc 

Once this conversion is made, some of the information present in the RAW file is lost in the resulting file and cannot be recovered.

One big advantage of shooting in RAW is therefore that it allows for a greater range of adjustments in contrast, brightness, shadows, highlights, and so on, along with the full style of the photographer to be applied. You decide, not the software in your camera or on your PC, how you want to the RAW file to be developed into a photo, in a non-destructive way, always being able to change your adjustments without any loss of the original data.

That is what the development software helps you do: transform the full data from the raw file into an image that takes into account your choices among the full range of possibilities.

For example, you won’t lose details when you edit a RAW file and need to brighten the shadows and bring down the highlights. On the other hand, you won’t be able to do much with a JPEG as the information has been lost.