RawDigger and FastRawViewer have released the beta version of an application called DPRSplit, designed for Canon 5D Mark IV owners. With DPRSplit, photographers can input a CR2 file from a Canon 5D Mark IV and then extract a second image from it, one with an exposure value that is about one stop lower than the original CR2 image.
This utility works only if the camera’s Dual Pixel Raw mode was enabled when the shots were taken.
Canon explains how this technology works on its website:
The Dual Pixel sensor’s pixels have a dual photodiode construction. This sensor design means the sensor can receive an A and B signals from the subject and to detect any phase differences between the two signals, allowing them to attain focus as part of the Dual Pixel AF system … During Dual Pixel RAW shooting, a single RAW file saves two images into the file. One image consists of the A+B combined image data and the other only the A image data.
Photographers benefit from this technology by using Canon’s Digital Photo Professional software, which enables users to make “microadjustments” to focus, bokeh shift, and reduce ghosting. However, the software doesn’t enable users to extract both images from the CR2 file separately—that’s where DPRSplit comes in.
With this utility, photographers get access to that second frame, which has half the light of the composite image. This means that, in essence, the camera is automatically capturing two shots, bracketed by about 1EV.
Extracted images are saved as DNG files for editing with any software that supports the format, so you can blend the images back together and get about +1EV more usable dynamic range. And since the exposures are captured simultaneously, you don’t have to worry about motion blur in your image. The only potential “issue” is a minor parallax error between the two frames.
DPRSplit beta 0.8 is free to download for Windows 7 or higher and Mac OS X 10.6 through macOS 10.13. As with any beta software, it is possible users will encounter bugs, but if you’re a 5D Mark IV user and you already shoot in Dual Pixel Raw, this one might be worth a shot.