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Comment by serviceberry | Hacker News Reader

> Clipped highlights in digital photography are simply impossible to eliminate in post-processing without conjuring nonexistent information. Even if you shoot raw.

Huh? This used to be true twenty years ago, but modern sensors in prosumer cameras capture a lot more dynamic range than can be displayed on the screen or conveyed in a standard JPEG. If you shoot raw, you absolutely have the information needed to rescue nominally clipped highlights. You get 2-4 stops of latitude without any real effort.

The problem here is different. If the rest of the scene is exposed correctly, you have to choose one or another. Overexposed highlights or underexposed subject. The workaround is to use tone mapping or local contrast tricks, but these easily give your photos a weird "HDR" look.

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You may be confused on at least two counts:

— If you think there is “clipping” and the somehow different “nominal clipping”.

Clipping is binary. Either you camera’s pixel clipped (i.e., accumulated enough photons to get fully saturated, and therefore offers no useful information for debayering), or it did not. If it clipped, then you lost colour data in that part of the image. If you lost colour data, and you want a colour photo, then in almost all cases one way or another you will have to rescue it by conjuring information up for the photo to look authentic and aesthetically good. (A lot of raw development software does it for you by default.) If the clipped bit is small, it is easy to do subtly. If it is big, which is a real danger with sun reflection bokeh, then… whoopsie.

— If you think modern sensors are safe from clipping.

This applies to any digital camera, from consumer to top professional models. Sensor bit depth is not even remotely enough to expose a scene with extreme highlights (e.g. sun or its reflections) without taking special measures regarding exposure at capture time. If you don’t tame highlights with a polarizing filter, you must dramatically underexpose the scene or they will clip.

They specifically clarified that they were talking about the JPEG/picture on screen, which has less dynamic range than the sensor and can clip without losing pixel information.

We are specifically discussing scene-referred image data—the raw pixel values obtained from a digital camera sensor. That is where unrecoverable information loss occurs at capture time. Parsing that data is when LR et al. engage various highlight reconstruction algorithms that fill in the missing information. My point is that a lot of that loss is often avoidable at capture time.

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