Understanding RAW Files: A Photographer’s Guide

Professional photographers need RAW files all the time. RAW files can be a game changer. These unprocessed, uncompressed image files give photographers unparalleled levels of control over the final image’s look and detail. In this article, you’ll find out about RAW files and how they’re produced by digital cameras. RAW image formats help professionals and amateurs alike produce finished image files that are incredibly detailed and versatile in terms of usage!

The New World of Digital Photography

In the world of Digital Photography, there are no negatives to process. This is a world where film negatives have been swapped for sensors, film grain has been swapped for digital image noise, where ISO and Colour balance are no longer difficult to deal with, and where the photographer processes his own photographs!

It’s a great time to be a photographer, and photography has never been as exciting as it is today!

The Benefits of Shooting In RAW Image Formats

So where do RAW image files fit into this picture? RAW files are the embodiment of this modern flexibility and control in digital photography. Unlike the fixed, processed image that a film negative represents, a RAW file is more akin to a digital negative, a raw canvas filled with untouched potential.

The Digital Darkroom

In the digital era, the photographer’s darkroom is now their computer, equipped with advanced editing software. When you take a photo in a RAW format (we will touch on them later in this article), the image data from the camera’s sensor is stored directly without any in-camera processing. This data captures minute details and a range of colors and tones far beyond what traditional film can achieve, or indeed what our eyes can see.

Choosing JPG vs RAW Formats

When shooting in JPEG, the camera makes certain decisions for you – such as sharpness, contrast, color saturation, and white balance. These are baked into the image and can’t be changed without losing quality. However, with RAW, these decisions are postponed until the post-processing stage. This affords the photographer the power to finely tune these parameters with software, yielding the highest quality results.

Amazing Flexibility When Processing Files

Moreover, ISO and color balance, which were once tricky to manipulate with film, are now merely metadata in a RAW file. These settings can be tweaked effortlessly in post-processing without degrading the image quality. In fact, errors such as overexposure, underexposure, or incorrect white balance that would have ruined a film photo can often be corrected when shooting in RAW. Always choose RAW if storage space is not a concern.

Digital image noise, the successor to film grain, can also be more effectively managed with RAW files. High-precision noise reduction algorithms in modern post-processing software can yield cleaner results when applied to the high-fidelity data in RAW files.

Digital Image Sensors For Cameras

CMOS Image Sensor Chip with RAW capability

Digital Cameras capture light using either a CCD or a CMOS sensor.

Sensors are made up of tiny photoreceptors that are sensitive to either Red, Green, or Blue light. The images that we see are a combination of different intensities of these three basic colors.

The information from these photoreceptors is processed by an image processor microchip and is encoded into JPG or TIFF format files. We can see these images on the LCD of the camera or on a computer. There are some disadvantages to this method of obtaining ‘finished’ image files. Let me list them for you.

  • Further tweaking of the image after it is saved as a JPG or TIFF results in some loss in the tonal range of the image and increased noise levels in some cases.
  • If your white balance mode is not set correctly, you could have one hell of a time trying to correct it and when you do, you’ll have a relatively noisy image. This is a bad, bad thing to do!
  • Highlights that are blown (overexposed without much detail) can never be recovered because there is no data in that area.
  • Any edits on the file are destructive edits. Meaning that once the file is modified and saved, the change to the pixel data is permanent and cannot be reverted. This, coupled with saving JPG files is a designer’s recipe for bad image quality!

RAW File Format Preserves All the Data!

Now, how does RAW help you overcome this?

The smart people among you would have realized by now, that the ‘RAW’ file format gives you the raw, unprocessed data that is recorded on the camera’s sensor. This enables you to forego the camera’s built-in image processing algorithms (also called de-mosaicing algorithms) and use one that you prefer.

This means that:

  • RAW files are uncompressed data from your camera’s sensor.
  • They usually have a higher number of colors (12-14bit) in each color channel than typical JPG or TIF files.
  • Even when processed, their original data is left intact, with various settings being applied only to the rendered output of the file, and not changing the file itself.

Structure and Contents of a RAW Image File

RAW files, as we will see, have different extensions and RAW is essentially a catch-all phrase for a number of different proprietary formats that contain direct sensor data. So, while the exact structure of the RAW image file would likely vary from one format to another, they generally follow a similar structure, as shared below.

  1. File header: This part of the file contains identifying information and metadata about the file itself.
  2. Camera sensor metadata: This portion includes information about the camera and sensor, such as the manufacturer, model, settings (ISO, shutter speed, aperture, etc.), date, and more. This data is important as it tells the software how to interpret the image data.
  3. Image metadata: This includes additional information like white balance, camera orientation, GPS data, and lens information.
  4. Image data: This is the raw pixel data directly from the camera’s sensor. A sensor will usually have a Bayer filter array, which means that each pixel only records one of three colors: red, green, or blue. The pixel data is typically stored in a mosaic pattern. There are twice as many green pixels as there are red or blue ones. This is because the human eye is more sensitive to green light. This raw data is often 12 or 14 bits per pixel in terms of shading information.
  5. JPEG preview: Many RAW files also include a full-size JPEG for quick previews. This is the image you see on your camera’s LCD screen after you’ve taken a picture.
  6. Thumbnail: A smaller JPEG used for even quicker previews.

When you open a RAW file in an image editor, the software performs a process called demosaicing or debayering. This interpolates the red, green, and blue pixel data to produce a full-color image. Then, the software applies various other corrections like removing sensor noise, correcting for lens distortion, and more.

All this can be highly customised to provide very specific image corrections based on the camera model, lens model, focal length information (if using a zoom), aperture, etc. Finally, these operations can be adjusted by the user, which is how RAW files get the flexibility that they are known for.

Software For RAW Editing

There are a multitude of RAW image processing software. Each company usually provides their own processing software. However, there are third party tools which often allow more flexibility, speed, image processing features, presets, optimised workflows. Faster processing and optimised workflows are important for professionals to allow images to be viewed, assessed, tweaked and output in high quality, as quickly as possible.

Personally, I prefer Adobe’s Photoshop Lightroom Classic CC, and Phase One’s Capture One Pro software… I like the user interface, and they way that they allow precise control over the white balance, the amount of sharpening applied, access to the “curves” and “levels” tools, and the option to use different color spaces and bit depths. These are among the most basic features. Other features like masking, AI based masking for facial features, sky selection and more allow very quick processin of individual as well as batches of images in one go.

Even more impressive than this list of plus-points, is the fact that all the changes that I make are not directly to the actual RAW file, but to a .xmp settings file or database… This means that if, at a later date, I decide that I don’t like the way that I’ve processed the file, I can go back to the file, revert to the original image and process it all over again (believe me, you will want to do this). It also means that I can get different looks by processing the same image in different software.

Here’s an updated list of RAW editing software:

  1. Adobe Photoshop Lightroom Classic CC
  2. Capture One Pro
  3. Skylum Luminar
  4. DxO Photolab
  5. RAW Therapee
  6. Affinity Photo 2.0

RAW File Formats

Since camera sensors have very specific parameters the files that they generate are also specific to the camera and camera manufacturer. As a result, the files are also rather specific in terms of the data that they store. There are quite a few formats available. Here’s the list for you to check out.

Camera ManufacturerRAW File Format
Canon.CR2, .CR3, .CRW
Nikon.NEF, .NRW
Sony.ARW, .SRF, .SR2
Fujifilm.RAF
Olympus.ORF
Panasonic.RW2
Pentax.PEF, .DNG
Leica.DNG, .RAW
Sigma.X3F
Hasselblad.3FR, .FFF
Kodak.KDC, .DCR, .DRF, .K25, .KDF
Minolta.MRW
Samsung.SRW
Ricoh.DNG
GoPro.GPR
DJI.DNG
Phase One.IIQ
Mamiya.MOS
Epson.ERF
Leaf.MOS
RAW file formats used by various camera manufacturers

The DNG File Format

Adobe DNG RAW File format

Think of it as a Digital Negative! In fact, that’s what Adobe is calling their standardized RAW format… the DNG format… There are some issues about the standardization of RAW formats at the moment because different manufacturers use different standards to define RAW image data… but that is something that we can discuss at a later date… for now, let’s talk about RAW’s problems.

File Size, The Major Problem

One of the major setbacks that photographers will face with the RAW format is the large size of RAW files. JPG files are typically quite compressed, and RAW files end up being about 5 times larger in size. This means that it will end up eating away at those megabytes on your CF, SD cards, and Hard Discs faster than JPGs. Storage and archival will eventually become an issue. However, storage media is getting larger and cheaper, so it shouldn’t be too much of a problem.

PROs and CONs of Using RAW Files

RAW files do have considerable advantages when used by professionals. However, there are considerable pitfalls too, when used by photographers who are not skilled, and equipped to handle these files.

PROs

  1. High-Quality Images: Since RAW files capture all the data from the camera’s sensor without any processing, they are able to be processed at a later date by updated software and get better quality output at a later date.
  2. Greater Flexibility: Compared to JPG files, RAWs hold incredible amounts of data which means that they can be edited more extensively and intensively in post-production without losing quality. You can adjust exposure, white balance, and other parameters without degrading image quality.
  3. Non-Destructive Editing: RAW files are not changed after they’re created in the camera, so any changes that are made in the editing software are saved to a different file. The settings are saved to a catalog file or an .xmp sidecar file.
  4. Better Detail: Since there’s more bit-data in each channel of the RAW file, gradients are smoother and there is less banding or posterization in textureless gradients (unlike JPG files).

CONs

  1. Larger File Sizes: As mentioned earlier, file sizes are considerably larger, requiring larger and faster storage media. More bits also mean more processing power is needed while editing and rendering out the files.
  2. Slower to write to disk: While shooting, the larger file size has another price that needs to be paid. Larger file sizes mean that the camera’s buffer fills up quickly slowing down the actual frame rate (FPS) that the camera can shoot. Some cameras require the buffer to be completely empty before they can take photographs once again. This means that there is a delay before photos can be taken.
  3. Requires post-processing: RAW files can’t be opened and viewed without special software. This means that they can’t be shared immediately after taking the photos, but must be processed into a JPG, TIFF, or other file format.
  4. Compatibility: Not all image-viewing software can open and display RAW files.
  5. Learning Curve: There is a considerable learning curve in understanding some of the ideas behind RAW processing, and some of the concepts may not be immediately apparent for beginners to understand.

Conclusion: RAW Files Are Indespensible

RAW files are specialized tools that can be used by professionals to create high-quality output images. However, there is always a learning curve with RAW files, as well as some pitfalls to using RAW files in your photography workflow. It’s important to understand how RAW files fit in before committing to using RAW.

At the same time, it’s important to remember that RAW files represent a new level of freedom in the digital photography world. They are a cornerstone of modern photographic technique, providing incredible levels of control over the final image. It is a leap forward from film photography, offering the photographer the ability to fine-tune their vision even after the moment has passed.

Tell us how you use RAW files in your phootgraphy workflow, and if there was one, what was the turning point when you switched away from using JPG files… The comments are open.

The article was originally published on Umesh Gopinath’s blog, WhiteSpace. You can find an archive of it here.

Susheel Chandradhas

Susheel Chandradhas

Susheel Chandradhas is a Product Photographer and Filmmaker based in India. He has been taking photographs (almost) all his life. He has a diploma and a bachelors degree in Visual Communication, where his classmates all believed that he would write a book on photography... Instead, he writes on this website (because - isn't a community more fun?).

His passions include photography, parkour, wide-angle lenses, blue skies, fire extinguishers, and fast computers.

In addition to writing for Beyond Photo Tips, Susheel is a staff writer for Fstoppers.com, and owns and runs ColoursAlive, a photography, and video production studio.

You can connect with Susheel on Twitter, Instagram, or LinkedIn.

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