Review: DxO PureRaw

To achieve optimal quality in final image output, you must start by capturing images in a raw format file. Raw files record the numerical data that the sensor measures at each photosite. This data is first processed in a raw file converter by image processing software before image adjustments (white balance, exposure, contrast, etc.) can be performed. That first processing step, converting unprocessed data to a viewable image, is the most critical aspect of getting an optimal result. DxO’s new PureRaw software performs that step, then passes the image file to your favorite software for adjustment.

Most major image processing software companies pay less attention to raw file conversion than to image adjustment. This is one reason why raw files processed in software provided by camera manufacturers generally result in sharper, more detailed, and less noisy images. Unfortunately, camera manufacturer software is only now reaching a level of ease-of-use that’s attractive to users, and who wants to learn a new image processing application if you’re comfortable with your existing workflow (even if you’re sacrificing a bit of quality)?

DxO PureRaw is a solution. PureRaw converts the raw file’s numerical data into an RGB image (demosaicing), reduces image noise (denoising), and applies optical corrections (vignetting, optical distortions, chromatic aberrations, sharpness) based on DxO optical modules. These are all described as linear restorations from the numerical data. PureRaw leaves the rendering of the file (white balance, color, contrast, etc.) to the user’s personal taste and vision by creating a DNG file you can process in your favorite image enhancement program.

I opened DNG files that I created with PureRaw in Affinity Photo, ON1 Photo Raw 2021, Exposure X6, and Skylum Luminar AI Master, as well as Adobe Lightroom Classic 2021 and Photoshop CC 2021. All the programs were able to read the DNG files, but the exposure, color, and contrast were slightly different in each. This is a result of the non-Adobe programs applying their own DNG conversion algorithms to the files.

DxO created PureRaw to be especially compatible with Adobe imaging programs (Photoshop, Lightroom, and Photoshop Elements). When you export PureRaw DNG files to Adobe programs, there are instructions embedded in the XMP metadata to instruct the raw conversion algorithms not to apply denoising or lens corrections. Other software would require you to turn off these instructions manually, if possible. I never did and never found it to be an issue, but the non-Adobe software required different color and contrast adjustments to match the look of the same image processed in PureRaw and passed on to Photoshop or Lightroom.

The workflow in DNG is simplicity itself. Open the program, navigate to the raw files, and load them as thumbnails. PureRaw loads the images vertically in the interface by date, then horizontally for all images with the identical date. Select the images to process and click the Process Photos button. Once that’s complete, export the DNG files wherever you’d like and proceed with your standard image adjustment workflow.

PureRaw allows you to view unprocessed or processed images alone, or both versions as a single image with a before-and-after slider. To get proper optical corrections, you’ll likely need to download a DxO optical module that corresponds to the camera and lens you used. This takes only a few seconds and requires an internet connection. In time you’ll build up a library of these modules for your cameras and lenses, but I was disappointed that PureRaw did not access the module library created by DxO PhotoLab software.

The only real internal option offered in PureRaw is the type of processing to apply to your files. Three methods are available: HQ, Prime, and DeepPrime. The difference lies in the level of noise reduction applied.

• HQ processing is the fastest and is suited for images exposed under normal lighting conditions at reasonable ISO settings. The speed gain is welcome when you process an entire folder of raw files.
• Prime is an earlier DxO process designed for images shot in low light at high ISO settings. It uses DxO proprietary Prime noise reduction technology, and from my experience the resulting noise reduction is extraordinary. It’s also the slowest of the processing options.
• DeepPrime generally lies between the two in processing speed depending on the power of your CPU/GPU. It further extends the low-light capabilities of Prime denoising by combining that process with demosaicing to recover image and color detail that are often lost in raw file conversion. I settled on using DeepPrime on raw files unless I had a large number from a single assignment.

Other than the additional processing time when using PureRaw, I found another small drawback—the increase in file size. Storage needed for the DNG files is two to four times greater than the original raw file. This is the result of storing all three color components at 16 bits per pixel rather than the 12 or 14 bits of the original raw file. DxO recommends also saving the original raw file should you wish to process it in the future.

I tested PureRaw with raw format files from Canon, Fujifilm, Leica, Nikon, and the latest 60-megapixel Sony. It processed all the raw files other than the DNG from the Leica M8, even though DNG files are listed as being supported. Processing time in the DeepPrime method, including files from the Sony, was about 30 seconds per file. The Sony DNG output grew to a whopping 225MB.

An additional advantage to PureRaw is repurposing older raw files. Technology and time both march on, and treasured digital files captured in raw with my early Nikons took on new life when processed using PureRaw and then reprocessed in Photoshop.

For photographers seeking to extract maximum detail from new or old digital files with the absolute least amount of noise, DxO PureRaw is worth exploring. It’s priced at $89.99.

Stan Sholik is a writer and photographer in San Clemente, California.