Radiometric interpretation of Apple ProRAW and Bayer RAW access via AVFoundation

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Created May ’26

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I am working on a computational photography research project involving multi-exposure HDR reconstruction using Bayer RAW and Apple ProRAW captures. I would like to clarify the radiometric interpretation of Apple ProRAW and the availability of Bayer RAW capture through AVFoundation.

My questions are:

1.On current iPhone Pro devices, is it possible for third-party apps to capture and export true Bayer-pattern RAW DNG files through AVFoundation, rather than Apple ProRAW linear DNG files? If so, which availableRawPhotoPixelFormatTypes correspond to Bayer RAW, and what device or format restrictions apply?

2.Apple ProRAW appears to be demosaiced and computationally processed, and may include multi-frame fusion. Is the decoded ProRAW image intended to be radiometrically linear and scene-referred?

3.For a bracketed ProRAW sequence captured with fixed ISO, white balance, lens, and focus, but different exposure times, can one assume that the decoded linear pixel values Y_i(p) satisfy an exposure-proportional model in non-saturated regions, such as Y_i(p) ≈ t_i R(p), across brackets?

This question is about radiometric consistency for algorithmic use, not about visual editing or tone mapping.

Thank you for your help.

Answer 1 · 2h

BinnedAndProud OP

2h

On the radiometric side, the two paths return different data, not two names for the same data. From published readouts of Halide captures on an iPhone 12 Pro main camera (iOS 14.3 era): the Bayer DNG is mosaiced — Color Filter Array, 1 sample per pixel — with BlackLevel 528 and WhiteLevel 4095. That is a 12-bit sensor readout with a real pedestal. The same author's ProRAW file from the same camera reads BlackLevel 0, 0, 0 and WhiteLevel 65535 x3, with NoiseReductionApplied 0.95 against 0 in the Bayer file: normalized linear RGB, already demosaiced and partially processed. A telephoto readout tells the same Bayer story — iPhone 11 Pro telephoto, Halide II, iOS 18.0.1: Color Filter Array, BlackLevel 528.

Does true Bayer DNG capture exist via AVFoundation? Yes, through third-party apps — but on Quad Bayer devices it is the binned stream. Reeflex states it directly: its RAW mode produces standard Bayer RAW (CFA) DNGs, and on Quad Bayer iPhones that means 12MP files, because 4 pixels are grouped in a single color in the Bayer pattern. 48MP on those devices exists only as ProRAW.

That gap is what FB25352517 asks Apple to close — full-resolution Quad Bayer RAW for third parties — and a supplement answering the DTS engineer's specifics is posted in thread 853978, where he confirmed the feedback is open and under investigation.