The RAW file in underwater photography : optimize post-production
Raw : the perfect format for underwater pictures !
You shoot pictures in jpeg but you don’t like how your underwater pictures turn out. You think the colors are too saturated or that they somehow don’t match reality. You would like to get better in post-processing but you get confused by the different settings of your camera. You are wondering about this RAW format that everyone is raving about?
Then this article is for you.
Everything is in the title: this article is written for photography beginners (underwater or not), but even knowledgeable amateurs and professionals can learn a thing or two. The RAW FORMAT is every picture-taking diver’s best friend!!
Understanding the RAW format
Many beginner photographers seem to know little about the RAW format, and thus don’t use it. You hear now and then about how it’s heavy and complex, and hard to work with. That it’s made for “pros”. This is why most people start working with the jpeg format of their compact or reflex cameras, using predefined settings (landscape, portraits, night, or even underwater…). It’s convenient, the pictures are flashy and can be posted to social medias or filed without any processing. But people need to know that these modes are algorithms processing pictures in RAW to convert them into jpeg.
Indeed, your camera shoots in RAW: it’s its native format. You can compare it to digital negatives vs. analog negatives.
As implied by its name, the RAW format is a collection of raw information coming from the light recorded by the captor. This data is processed to create a picture. That is what algorithms do.
Why you should be the one doing the processing, if it can be done directly by your camera?
Because that is what any self-respecting photographer should do!
RAW pictures need to be processed to create a jpeg picture, and you shouldn’t have the camera do the work for you. Some photographers call this work “retouching”, but I don’t like this term as I find it depreciatory and unsuitable. I prefer talking about image processing (post-processing), as it is exactly what is being done: processing data.
The processing is an integral part of a photographer’s work.
The jpeg format from the camera is far from being THE absolute truth, especially in underwater photography, as algorithms from cameras are created for land-based pictures.
The RAW format’s potential is often ignored by young photographers, and yet it is the only format that allows for an important leeway and a better control of post-processing, and thus of the final rendering of your pictures.
RAW format and not RAW picture
You may have noticed that I have been writing about RAW “format” since the beginning , not using the term “RAW image”. That is simply because RAW is not an image, but a gathering of data. It’s the digital negative (as it was before in analog), and it needs to be manipulated, interpreted by the photographer to become a picture (you have to accept that what you see in your camera’s screen is not the absolute reality!); If a RAW file needs to be interpreted to become a picture, that means that there is a infinity of possibilities for how the picture may turn out, and thus a multitude of different possible images for the same data.
The RAW is simply the recording of photons hitting the sensor during the exposure. At that time, a lot of information is not recorded, such as luminosity, contrast, white balance, colorimetry…
That is why a RAW file doesn’t turn out the same way depending on the software it is worked with (DPP, Lightroom, DXO…).
The gathering of this data makes the picture
So RAW processing is basically creating a picture. The photographer creates the picture according to his or her memories, experience and own sensibility (which is not, I repeat, the job of the camera’s algorithms!)
I think this work is very important: it’s how the photographer puts his mark on the picture.
To understand the raw format
Pour bien comprendre ce qu’est le RAW, revenons un instant sur le fonctionnement du capteur de votre appareil photo.
Let’s take a moment to talk about how you camera’s sensor works, how it “translates” the light it receives into a picture.
All digital cameras record in RAW the data from the sensor: it’s the transition from light to digital signal. For the camera to record colors, coloured filters are used to isolate a specific color (red, green, blue).
Each photosite records a color according to the Bayer filter.
Color-demosaicing is used to create the picture
That’s the moment when RAW is very important: isolating each color allows you to interpret the final color rendering of the picture in various ways.
This subtlety in colors is especially relevant in underwater pictures, when processing the different shades of blue.
The more data you have, the more subtle your shades of colors will be.
The differents raw formats
Different RAW formats belong to different manufacturers (CR2 for Canon, NEF for Nikon…), because in the first steps of RAW, the absence of norms and regulations made the different brands all create their own data coding.
Adobe then created the DNG format (Digital Negative Converter) to regroup and “standardize” the RAW format. DNG has already been adopted by brands such as Leica or Hasselblad.
Unlike other RAW formats, DNG has the benefit of containing all the metadata from the file.
Why you should use the raw?
You are starting to get my point: choosing RAW is a technical choice, as well as an artistic one!
An artistic choice
By choosing RAW, you choose to completely control the work from the beginning to the post-processing, because creating a picture doesn’t stop at the shot.
Imagine you are a baker. You buy all the ingredients to bake a cake. But once you have everything, you let someone else bake the cake.
Would you say you made the cake?
I don’t think so.
It’s the same thing for photography: you need to “bake” your picture to be the creator, the artist.
Because a picture is worth a thousand words, here is the comparison of three photographs
The picture on the left was created from the RAW file using Photoshop’s Camera RAW software. You can see it is flat, with close to no contrast and dull colors.
The picture in the middle is a jpeg picture created by the landscape mode of my camera. You will notice the saturated colors, the strong contrast and the loss of information from the darker parts of the picture.
The picture on the right is a jpeg generated after the photographer’s post-processing. You can see how much more subtle the process is compared to the camera’s jpeg. The contrast and colorimetry are more delicate. The information from the darker parts stand out more than in the two previous pictures.
Having control over the whole process gives a great autonomy and a total freedom to the photographer. No elements of interpretation must be left to algorithms, especially in underwater photography, as they are not designed for processing this kind of pictures.
A technical choice
Of course, a jpeg can be processed, or rather corrected. But there will always be a deterioration of the original file (the data). The RAW format offers a great advantage: you can process the data without altering the original file, as it brings the changes to a text file, and not to the original one. As a shot is rarely perfect, some notions still need to be rectified, such as white balance, exposure, dynamic range, some details to “extract” from dark or light areas in the picture or even some tonalities to adjust.
Example of information retrieval from dark areas in a RAW underwater picture
This correction to add to your pictures is even more relevant for underwater work. With the jpeg format, these adjustments are very limited, and you quickly reach, when trying to adjust some elements, an inelegant finish… That is especially true when trying to retrieve some information from lighter or darker areas. The RAW format is an advantage for all, and especially for underwater photographers who are dealing with strong dynamic range and a constant correction of tonality and white balance when post-processing their pictures.
Main advantages of using the RAW format
RAW format records in 12 or 14 bits, and the work is done in 16 bits. In comparison, jpeg is coded in 8 bits (for screen display or printing, it’s enough, but it’s not for digital processing)
- Correction of contrast, saturation and luminosity that is less destructing
- Total control of white balance in post-processing (very useful in underwater photography where white balance is essential in getting a “faithful” finish)
- Choice in color space
- Wider dynamic range
- More information to retrieve from high and low lights (the newer the captors, the wider the retrieval)
- Reliable noise reduction
It’s easy to see the numerous advantages of using Raw. What’s more, with the evolution of captors, the possibility of information retrieval from high and low lights is becoming more and more efficient.
Conclusion on the RAW format
The RAW format is unavoidable when processing pictures. Just like the analog negative, it is the base, the raw material of a picture development process. Its strength and sharpness make it essential. It is the format needed to make the most of your camera. The finish of your underwater pictures will be improved, with a better dynamic and a subtlety in colors that you won’t find in any other format. To master this format is not easy: it takes a lot of time and practicing! I will give you the bases for a good post-processing work in my next article: