The A to Z of Photography: Raw

RAW files are unprocessed image files captured directly from your camera's sensor. They have been called the equivalent of a "digital negative", but it would be equally accurate to think of them as the "undeveloped" digital image.

So, what is the difference between the raw files and the JPEG images produced by your camera? All digital cameras can produce JPEG images. These are ready-to-process image files ready to view, share and print. JPEG is a kind of universal file format for photos, which does not take up much space and can be viewed and shared on any device.

But the camera's sensor actually captures much more information than what is seen in the JPEG image saved by the camera. Many of these excess data are discarded when the camera applies the settings you have chosen in the camera, such as the white balance or the style of the image, and because the JPEG image format simply can not contain all the data captured by the camera. sensor. 19659002] However, more advanced cameras can save the original raw file of the camera instead of a processed JPEG image, or both at the same time. It's better to see them as a digital negative, while a JPEG is more like a 6 x 4 print of a street lab.

These raw files must be processed with the raw conversion software before they can be viewed, edited or shared in the normal way, which is inconvenient. But they contain a lot of useful additional data, so it is possible to extract a wider range of tones from your photo (dynamic range), select a white balance setting later than at the time of shooting and apply image adjustments heavier without degrading the image quality.

The process of digital images

Here is a brief guide to the process of capturing images to show where the raw files fit.

Step 1: The camera sensor captures the light values ​​as analog signals

Step 2: Its built-in analog-digital converter converts them into digital data: this is the file unformatted

Step 3: The camera generates a JPEG image processed by "demosaicing" the red, green and blue pixels captured by the camera

Step 4: White balance also applies , contrast, color, sharpness and other settings you have chosen in the camera

Step 5: JPEG images can store only a limited amount of data (8 bits per channel of red, green and blue, for people with a technical mentality), so a large amount of unused data is discarded.

When you capture a raw file, you are intercepting the image in stage 2, after the analog operation digital conversion Then you can use more powerful raw conversion tools on your computer to control the way it is processed or processed. ; develop & # 39; the file without formatting At the end of the process, you can create a more refined JPEG image or use the higher quality TIFF format. With TIFF you can create 16-bit images that support image manipulation much better than JPEG images.

If you have a file without format, you can "develop" it to offer a much more pleasant result using software such as Adobe Photoshop Lightroom.

Unprocessed file numbers

It is annoying that each camera produces its own unprocessed file type, so if you use third-party flat conversion software such as Adobe Camera Raw, Lightroom, Capture One or DxO PhotoLab, you may have to wait a few weeks to receive support for a new camera to arrive.

Each manufacturer uses different file extensions for their flat files. The Nikon raw files have the suffix .NEF, the raw files of Pentax end in .PEF and the raw files of Fujifilm have the suffix .RAF, for example.

Adobe has tried to produce a universal .DNG raw file format, and while it offers a free DNG converter to convert any raw file owned in this format, the DNG format has not been incorporated and has come in different versions throughout of time, so not all programs that support the DNG format can read all the different DNG versions.

Raw files can not be edited; you can not make permanent changes to them the way you can with other image formats

The different raw conversion tools also produce very different results, so it is often more useful to think of raw files as & # 39; Negative undeveloped & # 39; Adobe Camera Raw, Capture One Pro, DxO Photolab and a set of other tools will produce different versions of the same file without formatting. Expert photographers will often have a favorite unformatted converter in the same way that traditional movie photographers would have a favorite developer.

Raw files can not be edited; You can not make permanent changes to them in the way you can with other image formats. This is good in a certain way because it means that you will always have the original image, they are not destructive. It means that the raw processing software should save its settings as "metadata", process the stored instructions together with the raw file or in an image database, instead of inside the file itself.

Pros without file format

  • You can choose white balance settings later, regardless of the setting you recorded with
  • There are usually additional details of light and shadow in the raw file that can help you solve exposure problems in bright skies and dark shadows
  • Raw conversion software will often give you better sharpness and noise control than those obtained with JPEG on the camera
  • You can export 16-bit TIFF files that are much more suitable for heavy image manipulation than JPEG

Raw file conventions

  • Raw files take up more space on your memory cards and your computer
  • If you shoot sports, you reduce the number of shots that you shoot can perform in a burst
  • Must be processed later, which adds an additional step to your photo workflow [19659] 023] Sometimes it takes a bit of work to match the quality of a JPEG on the camera, it does not matter to improve it
  • Adobe Photoshop Lightroom CC review

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