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by prakhunov 2149 days ago
That isn't the same type of HDR that these HDR modes on cell phones are. You seem to be confusing bit's with stops of dynamic range.

To simplify I'll pick a grayscale image so with 8bits you would only have 0-255 as pixel values for the intensity.

With 12 bits you'll have 4096, and so forth.

What cellphone HDR usually does is take the image at a high exposure and a low exposure and combine the result. (Also the sensors inside the cellphone are also more than 8bit)

Even if you take a 12 bit photo if it's overexposed you can't do much. All you get is more play but it doesn't solve the fundamental problem of too much light hitting the sensor, or vice versa if the image is underexposed.

Now there are more advanced camera sensors that let you set the exposure time (or usually the ISO (which just translates to gain) at specific horizontal points of the sensor so that you can get even better images in one frame.
2 comments
bscphil 2149 days ago
> You seem to be confusing bit's with stops of dynamic range.

This is correct, they seem to be mistaken. I've seen this mistake many times in this thread. I wrote a comment in reply to one of them explaining in some detail what the point of higher bit depths and "HDR" (as a set of technology standards) is: https://news.ycombinator.com/item?id=24044818

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formerly_proven 2149 days ago
Your remark (~"x bits worth of luma doesn't necessarily correspond to x stops of DR on a display") is entirely correct but is tangential to my point. You can't encode a scene with more than 8 stops of dynamic range into an 8 bit JPEG without either loosing details or performing a tone-mapping-like process.
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formerly_proven 2149 days ago
> That isn't the same type of HDR that these HDR modes on cell phones are. You seem to be confusing bit's with stops of dynamic range.

I'm aware of the difference between bracketed HDR and what these cameras do, but that's besides the point. If you capture RAW+JPEG it's pretty obvious that the camera is not using a flat curve, but that it is quite clearly doing something similar to tone mapping around highlights and shadows, and it's not fixed either, but slightly different for each shot.

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