the fast & minimal camera
dedicated to raw Bayer photography
USER'S MANUAL
Basics
Bayer RAW is as raw data as you can get, straight from the sensor chip.
In the camera world, it has historically been called just RAW - but it is increasingly refered to as "Bayer RAW" to be unambiguous, especially in the Apple world where Apple ProRAW makes things confusing.
All iPhone models back to the iPhone 4s can capture photos as Bayer RAW (but Apple's Camera app has never supported it; you need to use an app like Bayer Cam).
In the camera world, it has historically been called just RAW - but it is increasingly refered to as "Bayer RAW" to be unambiguous, especially in the Apple world where Apple ProRAW makes things confusing.
All iPhone models back to the iPhone 4s can capture photos as Bayer RAW (but Apple's Camera app has never supported it; you need to use an app like Bayer Cam).
Demosaicking
Electronic photosites (sensor pixels) only respond to light intensity, regardless of color. The way we achieve color capture is by overlaying those photosites with a color filtered array (CFA) that alternates red, green, and blue colors.
Why those colors specifically? Human vision is trichromatic, which means the human eye is sensitive to 3 wavelengths of color, which roughly correspond to red, green, blue. The brain combines its perception of those 3 wavelenghts into what we call "color".
Why those colors specifically? Human vision is trichromatic, which means the human eye is sensitive to 3 wavelengths of color, which roughly correspond to red, green, blue. The brain combines its perception of those 3 wavelenghts into what we call "color".
"RAW capture" means capturing this matrix of red/green/blue light intensities. But we still need to turn those individual color measurements into unified color for viewing; this is known as "demosaicking".
Demosaicking is the process of turning the raw, single-channel color pixels from a camera sensor into RGB pixels.
There are many different demosaicking algorithms, with different tradeoffs.
Bayer RAW captures the raw data, which can be processed at a later date.
Demosaicking is the process of turning the raw, single-channel color pixels from a camera sensor into RGB pixels.
There are many different demosaicking algorithms, with different tradeoffs.
Bayer RAW captures the raw data, which can be processed at a later date.
Processing
Even after demosaicking, the image is not ready for viewing. It needs to undergo a number of subsequent processing steps (white balance, sharpening, denoising) that are each configurable and can highly change the final appearance of the image.
This is why Bayer RAW is so valued as a format: it gives you as much control as can be had over the production of a final, processed, ready-for-viewing photo.
This is why Bayer RAW is so valued as a format: it gives you as much control as can be had over the production of a final, processed, ready-for-viewing photo.
Bit Depth
A key notion to be familiar with when talking about RAW files is bit depth. This is the number of bits that are used to represent each color component (red, green, blue) for the pixels in the image.
The bit depth of a digital photograph can be loosely equated to the dynamic range of a film photograph: the luminosity values for each pixel are stored on n-bits, where every increase of n by 1 leads to a doubling in light values.
Most displays are 8-bit per color channel (= 24 bits for RGB), and that's the bit depth standard JPEG uses.
For photographic capture, working in 8-bit is problematic because it means you have no headroom or floorroom to shape the image. Hence advanced digital cameras offer 10 or 12 bit capture, or even 14 or 16 bit capture at the very high end.
The bit depth of a digital photograph can be loosely equated to the dynamic range of a film photograph: the luminosity values for each pixel are stored on n-bits, where every increase of n by 1 leads to a doubling in light values.
Most displays are 8-bit per color channel (= 24 bits for RGB), and that's the bit depth standard JPEG uses.
For photographic capture, working in 8-bit is problematic because it means you have no headroom or floorroom to shape the image. Hence advanced digital cameras offer 10 or 12 bit capture, or even 14 or 16 bit capture at the very high end.
Every iPhone device to this day shoots 12-bit Bayer RAW files.
One way you can independently verify the bit depth of an image is to inspect the WhiteLevel field in the DNG section of the file's EXIF metadata - it will be set to 4095 (212-1) for 12-bit, and 1023 (210-1) for 10-bit.
One way you can independently verify the bit depth of an image is to inspect the WhiteLevel field in the DNG section of the file's EXIF metadata - it will be set to 4095 (212-1) for 12-bit, and 1023 (210-1) for 10-bit.
Bayer RAW vs Apple ProRAW
There is often confusion between Bayer RAW and Apple ProRAW.
Apple ProRAW was introduced on iPhone 12 Pro (with iOS 14.3), and is available on all subsequent Pro models - but only Pro models, regular iPhone devices (including iPhone Air) do not support Apple Pro RAW capture.
Apple's stock Camera app, the one that comes preloaded on iPhone, can capture Apple ProRAW.
On the other hand, a 3rd-party app such as Bayer Cam is needed to shoot Bayer RAW (3rd party apps can capture Apple ProRAW too).
Apple ProRAW was introduced on iPhone 12 Pro (with iOS 14.3), and is available on all subsequent Pro models - but only Pro models, regular iPhone devices (including iPhone Air) do not support Apple Pro RAW capture.
Apple's stock Camera app, the one that comes preloaded on iPhone, can capture Apple ProRAW.
On the other hand, a 3rd-party app such as Bayer Cam is needed to shoot Bayer RAW (3rd party apps can capture Apple ProRAW too).
The confusion stems from two things:
- The stock Apple Camera app displays "RAW" in its format picker, when it actually means "Apple ProRAW".
- Despite the naming, Bayer RAW and Apple ProRAW are actually two quite different formats.
The table below sums up the key differences between Bayer RAW and Apple Pro RAW.
- The stock Apple Camera app displays "RAW" in its format picker, when it actually means "Apple ProRAW".
- Despite the naming, Bayer RAW and Apple ProRAW are actually two quite different formats.
The table below sums up the key differences between Bayer RAW and Apple Pro RAW.
Apple ProRAW is a processed format. From the moment the file is created, there are decisions about its rendering (demosaicking, denoising) that cannot be undone.
It does allow for far more editing latitude than other processed formats like JPEG or HEIC, but it remains fundamentally different from Bayer RAW in this respect.
It does allow for far more editing latitude than other processed formats like JPEG or HEIC, but it remains fundamentally different from Bayer RAW in this respect.
Another key way in which Bayer RAW and Apple ProRAW differ is that Bayer RAW phoots are a single sensor exposure, whereas Apple ProRAW photos are a composite from multiple exposures.
Apple ProRAW uses this technique to produce a high definition range (HDR) image, with little to no detail lost in either the shadows or highlights.
There is a clear upside to doing this; but it does mean that Apple ProRAW photos are fundamentally computational, and the notion of a single ISO or shutter speed for such a photo becomes quite fuzzy.
Apple ProRAW uses this technique to produce a high definition range (HDR) image, with little to no detail lost in either the shadows or highlights.
There is a clear upside to doing this; but it does mean that Apple ProRAW photos are fundamentally computational, and the notion of a single ISO or shutter speed for such a photo becomes quite fuzzy.
Finally, Apple ProRAW photos both include depth/semantic maps in their data, and make use of them for processing.
A depth map is an image that encodes the estimated physical depth for each pixel in the image. On iPhone, it is produced with a combination of physical sensors (LiDaR, stereo disparity) and AI.
A semantic map is an image that encodes what each pixel in the image might "mean", from a specified set of categories that are useful to photographic processing: sky, skin, hair, etc. Semantic maps are produced by AI.
These maps are then used to control the processing of the image, so that different corrections can be applied to different parts of the image (color balancing sky is not the same as color balancing skin).
There are pros and cons to this kind of processing. However, it is undeniably entirely unlike the kind of processing that happens in film photography, or traditional digital photography, and is a key difference between what it means to shoot Bayer RAW vs Apple ProRAW.
A depth map is an image that encodes the estimated physical depth for each pixel in the image. On iPhone, it is produced with a combination of physical sensors (LiDaR, stereo disparity) and AI.
A semantic map is an image that encodes what each pixel in the image might "mean", from a specified set of categories that are useful to photographic processing: sky, skin, hair, etc. Semantic maps are produced by AI.
These maps are then used to control the processing of the image, so that different corrections can be applied to different parts of the image (color balancing sky is not the same as color balancing skin).
There are pros and cons to this kind of processing. However, it is undeniably entirely unlike the kind of processing that happens in film photography, or traditional digital photography, and is a key difference between what it means to shoot Bayer RAW vs Apple ProRAW.
To wrap up, one format isn't "better" than the other; they just offer very different tradeoffs when it comes to capture and processing pipelines.
Apple ProRAW is best if you want the Apple's most advanced processing.
Bayer RAW is best if you want the unprocessed sensor reading, to which you can apply your own custom processing.
Apple ProRAW is best if you want the Apple's most advanced processing.
Bayer RAW is best if you want the unprocessed sensor reading, to which you can apply your own custom processing.