What is a RAW file?

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Before you take a picture, you decide in which type of file-format (jpg, RAW or both) your pictures will be stored in the camera.
A RAW file (CR2, NEF, ORF) contains the unedited signal of the camera sensor. You need special software, a raw converter / raw conversion software, to view or edit a raw file. Some camera manufacturers, like Canon, provide you with a free RAW converter when you buy their camera. A jpg file is already edited by the camera (color, contrast and sharpness) before the image is saved on the CF-card or SD card. Which one is better, RAW or jpg?

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When you're satisfied with the quality of the jpg files your camera delivers you, keep using them. Don't worry about all the fuss about the quality difference between RAW and jpg files. Keep on making pictures in stead of going into the digital darkroom with your RAW files.

In probably more than 99% of the images you make, a jpg file can deliver you a good enough quality to make a beuatiful print (see: JPG vs RAW: Get it Right the First Time). Jpg files offer several advantages over RAW files.
Jpg files are smaller than RAW files and thus you can store more images on your memory card or computer if you don't use RAW. Secondly, you don't need a special RAW converter to view or edit your images.

Another disadvantage of a RAW file is that each camera manufacturer has its own propietary RAW file (like CR2 by Canon, NEF by Nikon, ORF by Olympus etc.). Even within a series of cameras from 1 manufacturer, you will find several non-interchangable types of RAW files. Every time a new camera is introduced, a new RAW file comes along with it. It's questionnable whether all these types of RAW files will be supported in the future. Choosing RAW files only, you'll risk being left with an archive of RAW files which is just as incompatable with your latest photo-editing software as your slides or negative films. See an extensive discussion about this topic at OpenRAW.org. Adobe tries to unite all camera RAW files by offering a universal RAW file, called DNG. But sofar it doesn't look like this initiative has been successful.

Despite all the risks and disadvantages: if you like to obtain the highest image quality out of your expensive camera, stick to RAW files in stead of jpg files. Especially if you are going to do a lot of editing.

Advantages of a RAW file over a jpg file:

  • Color corrections, like adjusting the whitebalance of a RAW file, can be made afterwards without quality loss. Digital cameras are almost exclusively set to auto whitebalance. Sometimes, for example when you make pictures under artificaial light, the automatic whitebalance isn't accurate enough. RAW files offer here much more flexibility. The whitebalance of RAW files can be optimized during the RAW conversion at your computer. See for instance A camera RAW primer.
  • A RAW file offers more exposure leeway in comparison with jpg files. The highlights in a lightly over-exposed RAW files can be restored almost completely. The same image as a jpg file has insufficient information to restore these overexposed highlights.
  • Minder ruis: in de RAW converter kan je Luminance Smoothing en ColorNoise reduction toepassen (handig bij opnames met hogere filmgevoeligheid).
  • Choose for dfferent color spaces (s-RGB, Adobe RGB and in professional camera's even Prophoto RGB) without quality loss
  • Correction of chromatic aberration using the original sensor signal.
  • jpg files are already sharpened in the camera. If you find afterwards that the camera applied too much sharpening there's not much you can do about it without quality loss. Since you sharpen the RAW file afterwards while converting the file, a RAW file offers much more flexibility at this point. In camera reviews you often will find higher resolution values for RAW files due to a better apllied sharpening of RAW files.
  • a RAW file has a 12 or 14 bit color depth, whereas a jpg file only has a 8 bit colr depth.  Read our article about Posterization if you wish to know more about this.

More about RAW files:

 


Most of the mentioned advantages of RAW files will appeal to more experienced photograhers. Several sites have shown elaborate comparisons of RAW and jpg image quality, for example at Luminous Landscape or David Eppstein' site .

Ivo Freriks
Author: Ivo Freriks
With Camera Review Stuff I hope to make a modest contribution to the pleasure that you get from photography. By testing cameras and lenses in the same way, evluating the results and weighing up the pros and cons, I hope to help you find the right camera or lens.

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