Dual Pixel Raw Support for Canon 5D Mark IV from LibRaw (RawDigger, FastRawViewer)

2018-02-09 • SEND FEEDBACK |
Related: Canon, Canon 5D Mark IV, Canon DSLR, Expose To The Right, exposure, FastRawViewer, histogram, LibRaw, RawDigger

See my Canon wish list.

See Potential Uses for Canon 5D Mark IV Dual Pixels as per Alex Tutubalin of LibRaw.

Alex Tutubalin of LibRaw (RawDigger, FastRawViewer) writes:

I know, you're not big Canon fan, also 5D Mark IV is not high-megapixel camera, so your interest in this camera may be very moderate.

However, Canon 5D mk4 is the only camera that has 'Dual Pixel RAW' mode:

• In 5D4 sensor, each pixel is divided into two subpixels, oriented 'left' and 'right'
• In standard recording mode, aggregated two-subpixel signal is recorded in RAW, so not much difference from normal camera in terms of noise, resolution, and dynamic range.
• In Dual Pixel RAW mode, sem one subpixel set, is also recorded in CR2 file (resulting in 90+Mb CR2 size).
• These two sub-images are diffecond image frame, containing signal frorent in parallax (because left/right part of lens was used) for near object, but mostly the same for distant objects. Canon provides DPP utility, that allows (moderate) editing of sharpness zones, bokeh and lens flare.

The second frame is actually recorded at ~1EV lower than composite frame (half pixel area, same ADC, so same exposure results in lower signal), this creates possibility to recover additional 0.9-1 stop in highlight (here is our old article, RawDigger was used to display/extract second frame: https://www.rawdigger.com/howtouse/canon-dual-pixel-mode-highlights-are-there ). Unfortunately, no known software allows to use this extra stop in highlights in raw processing.

We just released DPRSplit utility for extract this second frame (or both): https://www.fastrawviewer.com/DPRSplit

Extracted second frame can be used alone (effectively, it is bracketed -1EV below composite frame, so if composite is overexposed, second frame will have no-so-blown highlight). Also, one can mix composite and second frames (e.g. in ACR/HDR merge mode), creating high-dynamic range image. For distant objects two images are very same (and exposed at very same time), so no problems with camera/object movement.

This is beta, but works fine in our tests. This will be free software after beta-test period. It is very similar in interface to SonyPixelShift2DNG (of course, large parts of SPS2DNG source code was used in this new program).

DIGLLOYD: I am not a “not Canon” guy, it’s just that Canon has sat on its hands for years now in terms of offering a high-grade high megapixel sensor.

See also:

• ETTR (Expose to the Right)
• Reader Comment: ETTR (Expose to the Right).
• Auto-ETTR Would Sure Be Nice — 2 Stops Below the Blow-out Was the Camera’s Advice
• ETTR — Real RAW Data vs Camera Info and Final Images, With Crops

RawDigger histogram showing a near perfect exposure within 1/3 stop of blowout