JPEG vs RAW vs DNG – Why you should shoot in RAW format and edit in DNG format

One of the first things I learned as an aspiring photographer, was to shoot in the RAW image format.  Why? Because it’s vastly superior to shooting in JPEG image format. Furthermore, converting the proprietary RAW images to the DNG format before processing them in your editing software of choice is also highly recommended.  The following diagram illustrates my recommended image formats to support a non-destructive workflow that stores your images in the highest quality and preserves them for the future.  I will explain that further in this article.

The topic of RAW vs JPEG image format is one of the never-ending topics in photography, and it is especially relevant to beginning photographers including people switching from using their phone as a camera to a ‘real’ one. Numerous articles have been written comparing the two formats, and I don’t want to repeat that information.  However, shooting in the RAW image format is so fundamental to learning and improving your photography (and it’s a pre-requisite for most of my tutorials) that I felt the need to write a short article about it.

In this article, you’ll learn what the RAW image format is, how this compares to JPEG, and how you can use RAW to create better photos.  Furthermore, it recommends that you use one specific RAW format, called DNG, when editing and saving your photos.  This article covers:

• What is a RAW image?

• What are the advantages and disadvantages of shooting in RAW?

• What is a JPEG image?

• What are the advantages and disadvantages of shooting in JPEG?

• How do RAW and JPEG images compare?

• What is DNG?

• Should you use DNG or proprietary RAW formats?

• How to set up a workflow optimised for RAW?

What is a RAW image?

A RAW image (also known as a “digital negative”) is an image file that contains unprocessed or minimally processed data from a digital camera’s sensor. Except for the DNG format, RAW is a proprietary format that is tied to a specific camera model, and different camera manufacturers use different formats.  A RAW image needs to be processed in software before it is ready to be printed, shared or shown on a display device.

RAW files typically consist of three main parts: the actual RAW data from the image sensor, a camera-processed full-size JPEG preview + thumbnail, and substantial header and metadata information. For cameras to be able to display the recorded image on the rear LCD or on the electronic viewfinder, the camera-processed JPEG preview is used. The image header, as well as parts of the metadata are used for interpreting sensor image data by RAW conversion software, while other metadata information such as exposure settings, camera and lens model, date/time, etc. can be used for filtering, sorting and cataloguing images.

What are the advantages and disadvantages of RAW?

The key advantages are:

• Far more shades of colour. The bit-depth of RAW images is 12-bit, 14-bit, or 16-bit.  This means that a RAW image can contain 68.7 billion, 4.4 trillion, or 281 trillion colours respectively.  Compare that to an 8-bit JPEG image that can only contain up to 16.8 million colours.  So, there’s a huge difference between RAW and JPEG in terms of capturing colour!  Check the bit depth of your camera to see how many colours it can capture (a Canon EOS R5 produces 14-bit RAW images when using the mechanical or electronic 1st-curtain shutter modes).

• Wider dynamic range. A RAW image contains a wider dynamic range compared to a JPEG image. JPEG images will have up to 1 1/2 stops of latitude before severe degrading of the image will occur. Whereas RAW images can have up to 3 stops of latitude before severe degrading will occur.  For highlight and shadow recovery when an image or parts of an image are underexposed or overexposed, a RAW image provides far better recovery potential compared to a JPEG image.

• Non-destructive editing. When a RAW image is generated, all camera settings, including camera-specific and manufacturer-specific information (also known as image metadata), are added into the file, along with the RAW data from the image sensor. This data is never changed.  Instead, modifications that you make to the image such as white balance, colour, brightness, contrast, and other adjustments is saved on top of the RAW information (usually in a separate file). This means that applications such Lightroom and Photoshop do not modify the RAW data itself, and you can always go back to the original straight-out-of-camera image.

• Proof of ownership and authenticity. Unlike JPEG images that can be easily manipulated, RAW images can be used as evidence of your ownership and authenticity of the photograph.

The key disadvantages are:

• Must be post-processed. RAW files require post-processing and conversion to a format like JPEG before they can be normally viewed, which adds time to your photography workflow.

• Requires more storage. RAW images take up much more storage space than JPEG images. This means that your memory cards can store fewer images and your camera buffer can fill up, causing the camera frame rate to drop down. You will also need more storage space on your computer and other storage devices (including storage for backups) to keep the RAW images you capture.

• RAW format compatibility. RAW files are not standardised across different manufacturers. For example, Nikon software cannot read Canon RAW files and vice-versa. In addition, not all image-viewers and editors can open all the RAW files. If you have a brand new camera that just got released, you might need to wait for a while for software companies to catch up and update their software so that your RAW files can be opened and worked on.  However, there is a DNG format that greatly alleviates this problem (see below).

• More files to manage. Because RAW files cannot be modified by third party software, your settings will have to be stored in a separate sidecar (XMP) file (unless you use the DNG format). In addition, you will most likely be storing post-processed JPEG images as well, which translates to more files to manage.

What is a JPEG image?

JPEG is the most adopted image format in the world today, with most display devices and software having built-in capabilities to read and display JPEG images.  It utilises lossy compression for storing and displaying digital images. Different levels of quality (typically in percentage) can be applied to compress JPEG images, which impacts the overall quality and the final size of the image. Lower quality conversion results in higher compression rates, smaller files and compression artifacts, while images saved with a higher quality setting will reduce the potential for compression artifacts at the cost of increased storage needs.

What are the advantages and disadvantages of JPEG?

The key advantages are:

• Already processed. JPEG images are fully processed in camera and all settings such as White Balance, Colour Saturation, Tone Curve, Sharpening and Colour Space are already “baked in”, or applied to the image. So, you do not need to spend any time on post-processing the image, it is basically ready to use.  As long as you’re happy with an image that corresponds to the manufacturers view of what a good image should look like.

• Small footprint. JPEG images are much smaller in size than RAW images and therefore consume a lot less computer and other storage.

• Ease of use. Most modern devices and software support JPEG images, making the format extremely compatible and practical.

The key disadvantages are:

• Far fewer shades of colour. The JPEG image format is limited to 8-bits, which forces a hard limitation of 16.8 million possible colours. This means that all those other colours that your camera is capable of recording are essentially discarded when the image is converted to JPEG format.

• Limited dynamic range and recovery options. JPEG images contain far less data, which significantly limits their dynamic range and recovery potential. This means that if you manage to overexpose or underexpose an image, it will be very difficult, if not impossible, to recover that data.

• Camera settings impact JPEG images. Since cameras fully process JPEG images, any camera setting that can damage the resulting image will be irreversible. For example, if you apply too much sharpening to your images, you will not be able to “unsharpen” them later.  Basically, the camera applies destructive editing and you cannot revert to the raw data used by the camera to create that JPEG image.

• Lossy compression. The “lossy” image compression algorithm means that you will lose some data from your photographs. This loss of detail, especially in highly compressed files, might result in posterization issues, as well as visible “artifacts” around subjects that might be visible to the naked eye (especially when viewing these images on a large display or printing them).

So, should you be using RAW or JPEG for your photography?

For me (and most other serious landscape photographers), shooting in RAW far outweighs the advantages of shooting in JPEG.  If you have ever tried to edit a JPEG image to correct the exposure or white balance, you know that you often end up with undesirable results, and you simply need to live with the image that the camera produced.  RAW makes a huge difference in being able to edit images, and you will often be able to make significant changes.  A special moment (whether that’s a wedding photo, or a unique landscape photo) captured in JPEG may be lost if you chose the wrong camera settings, but can usually be saved when captured in RAW.   

Although processing RAW files takes longer, many of these processing tasks (such as importing, applying basic development settings, exporting) can be automated and carried out in batch.

And, shooting in RAW enables you to create more unique images that express your photographic vision better, as you start with a neutral image and simply have more camera data to work with.

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What is DNG?

One of the downsides of RAW is the fact that RAW image formats are proprietary and specific to a camera vendor.  If camera or software vendors cease supporting that particular RAW image format, you will not be able to view or process these images.  That is putting images you have taken many years ago at risk.

DNG stands for ‘Digital Negative’ and it’s a generic RAW file. Meaning this is a standard format for a RAW file and will work on all image manipulation programs that process RAW files.

DNG files are just a different version of a RAW file, just like Canon’s CR2’s or CR3’s are different to Nikon’s NEF’s.   A DNG is a lossless RAW image format developed by Adobe and used for digital photography. It is an open-source file format meaning it’s free to use by anyone. It was launched in 2004 and all photo manipulation programs such as Adobe Lightroom, DxO, Luminar, ON1, Topaz Photo AI, etc. will enable you to work with DNG’s.

There are several advantages in using DNG’s, as follows:

• Smaller file sizes.

• Speeds up processing between Lightroom and Photoshop (slightly).

• Unifies different camera raw files to one generic file format.

• They are an archival file format.

• Edit settings are held within the DNG file and not on a separate XMP file.  However, edit data are kept separate from the original RAW data and therefore non-destructive editing is preserved.

• Can be edited in any RAW processing program.

And there are some disadvantages as well:

• Can take extra time to convert RAW files to DNGs.

• Could lose camera brand specific data. Having said that, only the camera manufacturer’s software will probably support this brand specific data. So, there would be little if any impact when using editing software like Lightroom.

Personally, I convert my RAW files to DNG for the following reasons:

• DNG’s are RAW images, so they give you all the benefits of the camera manufacturer’s RAW files (unless you’re using the manufacturer’s software which most people don’t).  I’ve never lost any data when converting files to DNG.

• It’s an archival format. E.g. in 20 years, Canon (or another camera manufacturer) might use a different RAW format and software may not support the old RAW formats anymore. A DNG is generic, like a JPEG, so it’s used to archive raw files.

• One file for the original data and the edits.  It holds the editing data in the DNG file and not on a separate xmp file which simplifies file management and reduces risk that you lose editing information.

• It unifies your RAW files. I use different cameras (various DLSR and mirrorless, drone, phone) that all produce RAW files in a different format.  Editing software like Lightroom also create new RAW files when merging images or applying noise reduction in DNG format.  I aim for consistency in my workflow and file management to keep it simple.

When should you convert your images to DNG?

• You can convert RAW images to DNG during the import process in Lightroom.  This increases the import time, but at least it’s all done.

• You can convert a RAW image to DNG just before you start editing them.  This means that you don’t waste time during the import process, because you’re only converting the ones you are working on. This also works well if you carry out any pre-processing actions, like noise removal, that can create a new DNG file.

• You can convert RAW images to DNG before you archive them.

I prefer to convert RAW images before I edit them.  That way, I have a consistent development process, don’t get a XMP sidecar file, and my picks are stored in an open, archival format, without losing time during the import.

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Conclusion

Summarising the above explanation and recommendations:

1. Use RAW instead of JPEG if you’re a serious photographer wanting to have as much control as possible while editing photos.

2. Convert RAW images generated by your camera to DNG format, as it’s not proprietary, simplifies your workflow and reduces the risk that you will be unable to open old RAW files in the future.

3. Export your RAW/DNG images as JPEGs to enable them to be shared and viewed outside the photo editing software.

So, switch your camera settings to shoot in RAW (check you manual, if necessary) and have fun shooting.  Please let me know in the comments if you have questions or feedback.

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