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Author Topic: Apple ProRAW and Halos  (Read 377 times)

Rajan Parrikar

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Apple ProRAW and Halos
« on: May 22, 2021, 07:08:21 am »

Looks like Apple is aggressive in pushing their RAW files from the iPhone before writing them to dng.

I'm attaching the original image (with everything in Adobe ACR zeroed out) taken with the iPhone 12 Pro, together with 200% and 400% crops. The halos are ugly.

This was taken with Apple's default Camera app. I wonder if there's a difference with some of the other apps like Halide, ProCamera, Manual, etc.


Guillermo Luijk

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Re: Apple ProRAW and Halos
« Reply #1 on: May 23, 2021, 08:43:54 am »

Could you please offer some Apple ProRAW for download? I guess they are DNG files, right? I'd be interested to analyse it with certaing depth.
BTW those halos seem to me the overlapping areas between differently exposed captures. The transition doesn't seem to be very soft, which is something at a first glance shouldn't be that much complicated.

Regards
« Last Edit: May 23, 2021, 08:46:57 am by Guillermo Luijk »
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Guillermo Luijk

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Re: Apple ProRAW and Halos
« Reply #2 on: May 23, 2021, 02:34:52 pm »

I managed to get some ProRAW DNG files from here: https://products.alessandromichelazzi.com/courses/apple-proraw-free-sample-photos
I downloaded the 7th sample: http://www.guillermoluijk.com/misc/proraw.dng

My conclusion is that Apple ProRAW is a 12-bit linear demosaiced (RGB) format, encoded in a 16-bit DNG file (blackpoint=0, whitelevel=65535), which can be built from a composite of several exposures to capture high DR scenes. This allows for RAW-class elasticity: exposure, white balance, shadow&highlights tone mapping over demosaiced data.

Strange saturation over the R channel in the RAW histogram:
http://www.guillermoluijk.com/misc/proraw_hist.gif

The scene without adjustments:
http://www.guillermoluijk.com/misc/proraw_linear.jpg

After ACR tone mapping:
http://www.guillermoluijk.com/misc/proraw.jpg

There may be visible seams between the captures as you experienced:
http://www.guillermoluijk.com/misc/prorawcrop.jpg

The baselineexposure metadata can be as high as above +3EV in some of the previous examples.

Regards

Rajan Parrikar

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Re: Apple ProRAW and Halos
« Reply #3 on: May 25, 2021, 02:36:18 pm »

Guillermo, I just saw your post requesting Apple RAW files. Thanks for the follow-up.

armand

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Re: Apple ProRAW and Halos
« Reply #4 on: May 26, 2021, 09:48:39 am »

It does this sometimes, particularly with high dynamic range scenes where it combines multiple shots and the stitching is not ideal. Often the jpeg is good enough though, with relatively impressive postprocessing capability in-phone (more than in LR). For tricky scenes or something that I think is a step above in merit I take both a jpeg and a raw shot.
All being said, it has very good results if you don't need to enlarge it, with way less work. I find that I'm using the iPhone extensively even when I  have a "real camera" with me.

Rajan Parrikar

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Re: Apple ProRAW and Halos
« Reply #5 on: May 26, 2021, 12:07:35 pm »

It does this sometimes, particularly with high dynamic range scenes where it combines multiple shots and the stitching is not ideal. Often the jpeg is good enough though, with relatively impressive postprocessing capability in-phone (more than in LR). For tricky scenes or something that I think is a step above in merit I take both a jpeg and a raw shot.
All being said, it has very good results if you don't need to enlarge it, with way less work. I find that I'm using the iPhone extensively even when I  have a "real camera" with me.

Armand,

The iPhone can do remarkable things, yes, for a sensor of its size, and it will only get better.

However, if I wanted to make something out of the above RAW file, it is a no-go. The file is far too fragile and the halos get accentuated with the slightest touch of Curves or Levels.
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