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What is HDR, anyway?

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791 points _kush | 1 comments | | HN request time: 0.199s | source
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dahart ◴[] No.43986653[source]
It seems like a mistake to lump HDR capture, HDR formats and HDR display together, these are very different things. The claim that Ansel Adams used HDR is super likely to cause confusion, and isn’t particularly accurate.

We’ve had HDR formats and HDR capture and edit workflows since long before HDR displays. The big benefit of HDR capture & formats is that your “negative” doesn’t clip super bright colors and doesn’t lose color resolution in super dark color. As a photographer, with HDR you can re-expose the image when you display/print it, where previously that wasn’t possible. Previously when you took a photo, if you over-exposed it or under-exposed it, you were stuck with what you got. Capturing HDR gives the photographer one degree of extra freedom, allowing them to adjust exposure after the fact. Ansel Adams wasn’t using HDR in the same sense we’re talking about, he was just really good at capturing the right exposure for his medium without needing to adjust it later. There is a very valid argument to be made for doing the work up-front to capture what you’re after, but ignoring that for a moment, it is simply not possible to re-expose Adams’ negatives to reveal color detail he didn’t capture. That’s why he’s not using HDR, and why saying he is will only further muddy the water.

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sandofsky ◴[] No.43990585[source]
> It seems like a mistake to lump HDR capture, HDR formats and HDR display together, these are very different things.

These are all related things. When you talk about color, you can be talking about color cameras, color image formats, and color screens, but the concept of color transcends the implementation.

> The claim that Ansel Adams used HDR is super likely to cause confusion, and isn’t particularly accurate.

The post never said Adams used HDR. I very carefully chose the words, "capturing dramatic, high dynamic range scenes."

> Previously when you took a photo, if you over-exposed it or under-exposed it, you were stuck with what you got. Capturing HDR gives the photographer one degree of extra freedom, allowing them to adjust exposure after the fact.

This is just factually wrong. Film negatives have 12-stops of useful dynamic range, while photo paper has 8 stops at best. That gave photographers exposure latitude during the print process.

> Ansel Adams wasn’t using HDR in the same sense we’re talking about, he was just really good at capturing the right exposure for his medium without needing to adjust it later.

There's a photo of Ansel Adams in the article, dodging and burning a print. How would you describe that if not adjusting the exposure?

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1. smogcutter ◴[] No.43991410[source]
> Film negatives have 12-stops of useful dynamic range

No, that’s not inherently true. AA used 12 zones, that doesn’t mean every negative stock has 12 stops of latitude. Stocks are different, you need to look at the curves.

But yes most modern negatives are very forgiving. FP4 for example has barely any shoulder at all iirc.