The raw image file format is arguably the greatest development in digital photography. When I first used digital cameras and JPEG image files, I wasn't very impressed as I could get a much better image from a digital scan of slide film. However, when I began to work with raw image files, I was amazed by the quality and versatility of the format.
What is a raw image file?
A raw image file contains all of the image data captured by the camera’s sensor. This means the data is not altered or processed in any way by the camera.
Why is raw better?
The answer is quite simple – raw files contain all the data from the camera’s sensor. This means that the image can be easily manipulated with software (for example, brightening the image or using a different white balance).
What is the difference between raw and JPEG?
Think of a raw file as a film negative and a JPEG file as a photo print. With the raw file, you can process and print the image in many different ways without impacting quality; however, the more you edit a JPEG, the more your reduce the image quality. This is because a JPEG image file is processed and reduced in size (compressed) by the camera, whereas the raw file contains all of the unprocessed data from the camera’s sensor.
The advantages of raw
Here are some of the main advantages of the raw format:
- The ability to adjust white balance in post processing. Of course, in an ideal world we should stop, measure the light and colour temperature, set the correct white balance for each photo and then shoot. In reality, this is impossible in most fast-moving photography environments, so use the auto white balance mode on your camera, shoot in raw and adjust in post processing.
- Exposure can be tweaked in raw files to a moderate degree without any significant loss in image quality. This means that if you have underexposed your photo a little, shoot in raw and adjust in post processing. Don't over rely on this feature though, because it is still much better to get the right exposure at the time of shooting. The reason for this is that when you adjust your exposure in post processing, you increase the digital noise in the image (even when using raw files).
- Raw files allow for great manipulation of any highlights and shadows so you can control strong contrasts in your images much more easily.
- Dynamic range is maximised with raw files, so you get better and more subtle gradation of extreme whites and blacks.
The disadvantages of raw
While there are some drawbacks to using raw files, I don’t think they are significant. For example, compared to JPEG, raw has larger file sizes, slower read and write times to memory cards and potentially requires more post processing. In reality this is all irrelevant – disk space and high-speed memory cards are now cheap and as long as you are using a powerful PC, processing is only slightly slower than with JPEG. Unless you are working in a very specific field where you may need immediate and instant uploading of JPEG images as you shoot (e.g. sports photography), I advise using raw for all your photography.