What Does Raw format mean in photography?

Posted on Dec 10th, 2020

What is raw format in photography?

What does raw format mean in photography? This is a question that I hear many times from my students.

Now more than ever since we are in a period of great “excitment” as regards raw format photography.

The reason is obvious, because it saw the introduction of the new Apple ProRaw format within the latest iPhone 12 Pro series. In any case, the raw format is also available on all latest generation Android smartphones and obviously on all digital reflex and mirrorless cameras.

In this article I will therefore go on to talk about what is raw format in photography and what are the advantages of using it.

The importance of the raw file in photography

When we take a digital image and look at it on screen, a lot of work has already been done upstream.

First the light was converted into a given binary data by the photodiodes on the sensor.

Demosaicing is then performed. This is one of the most important aspects in the world of digital photography.

In fact, the digital sensor, in the current state of technology, cannot see the complete information of the colors like the old analog films (apart from the sensor with Faveon technology) but uses a colored matrix placed in front of the sensor called “Bayer matrix” .

So imagine having a grid composed of a 4×4 pixel pattern (image below on the left) that is repeated on the entire sensor or 6x6pixel (image below on the right) as in the case of Fujifilm’s X-Trans sensor which is a variant of the classic Bayer setting.

This pattern, in the classic Bayer setting, is composed of two green pixels, a blue pixel and a red pixel.

You may wonder why there is double information for green pixels and the answer is given by the fact that our eyesight is more sensitive to green frequencies.

Very well, the fact remains that our digital image thus captured looks like a chessboard. Surely all other colors and their shades are missing. How do we get them?

This process of reconstructing the missing colors is done through demosaicing. There are algorithms (mathematical functions) that work to recreate the missing colors.

So when we get a jpg file from our camera, it has done the demosaicing process thanks to the image processor.

In addition, it applied the color settings we set in the camera (the various picture profiles or film simulations in the case of Fujifilm camera) and applied the white balance.

As a last step, it performs a lossy compression, which gives us a light and ready-to-use jpg file.

The raw file format

The raw file already contains the intent in its name.

So imagine bypassing the whole calculation phase carried out by the camera processor. The file is then written directly to the card in a format that is often proprietary. This file therefore has many advantages and some disadvantages.

The advantages of using the raw format in photography

The Demosaicization process was not done by the camera.

In this case we can use software on our computer to carry out this operation. I also point out that, with the improvement of technology, computing capacity and algorithms, an “old” raw file taken years ago could be developed with higher quality thanks to new software.

We can get our own look

Let’s imagine that from the same image we can get different looks. For example, I can get a development with little contrast, one that accentuates sharpness, one that makes the image almost analogue. I can also convert the image to black and white by working with the frequencies of the different colors to better balance the final result.

The final image can improve over time thanks to my new knowledge and taste

As a wine improves over time, an image can too! 😅

This is a fundamental aspect! In fact, our technical skills in using the software change over time and with them therefore also the final result we obtain.

A development made 10 years ago will be different from the one I will carry out today also because my personal taste may have changed over time.

In addition, the technology also improves and the algorithms too: they allow you to extract more detail and better recover the shadows and lights.

Maximum versatility in color change

In the raw file, the white balance setting is not written in the file, there is the initial reference from how it was set by the camera, so we can correct any green or red casts that arise in many difficult lighting situations.

We have the highest quality without information loss

No information compression was done with the raw file which threw away important data. We have them all available to get the most out of our image.

The disadvantages of using the raw format in photography

The file must be processed

The raw file cannot be taken and uploaded as it is online. It has to be processed with software due to its very nature as explained above. With the raw file I therefore need software as Lightroom or Capture One Pro for develop the image and finally get a jpg file to share on the web (or tiff without compression for printing).

I have to spend some time in post production work

This ties into the previous point. With the raw file I have to spend some time in the import process in the development software and later in the development of the file itself, going to adjust all the parameters to obtain the final photograph.

The file weighs more

Compared to a jpg file, the raw file can weigh 3 to 6 times more than the jpg file, due to the fact that no compression has been done on the file.

Most of the time it is a proprietary file

Despite Adobe’s work in creating a universal file called Digital Negative (DNG), manufacturers continue to use their proprietary formats that put software through continuous updating processes to read new files. In fact, let’s take the example that you bought the new camera from manufacturer X. Well, the development software Y you use will not see this new raw format until there is an update.

Who Uses the Universal DNG Raw Format?

These are the manufacturers that currently (late 2020) natively support the saving of files in the universal format DNG:

• Leica.
• Pentax using the option in the file save settings menu.
• Ricoh Digital GR.
• Sigma SD Quattro using the option in the file save settings menu.
• All Android smartphone manufacturers
• Apple with its ProRaw and saving a raw file from third party App like Halide or Moment.

What proprietary Raw formats are there?

All the other manufacturers that do not currently use the universal raw dng format use their own proprietary format which has the following names:

• .CR2 / .CR3 for Canon
• .Nef for Nikon
• .ARW for Sony
• .Raf for Fujifilm
• .Pef for Pentax
• .Orf Olympus
• .Srw mirrorless Samsung