Difference between dynamic range and latitude

Started Mar 29, 2018 | Discussions
The Davinator
The Davinator Forum Pro • Posts: 24,707
Difference between dynamic range and latitude

Anyone have any thoughts on this?  Had a few people lately claim they are the same despite the fact that definitions disagree.  Thoughts?

stevo23 Forum Pro • Posts: 24,735
Re: Difference between dynamic range and latitude

The Davinator wrote:

Anyone have any thoughts on this? Had a few people lately claim they are the same despite the fact that definitions disagree. Thoughts?

I would have thought that exposure latitude is a film term and dynamic range is a digital term. They behave differently. With film, we wanted to see how much we could expose before losing highlights. There was no recovery, you just looked for a good soft knee. With digital, we recover highlights.

No?

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Mr Garibaldi Contributing Member • Posts: 799
Re: Difference between dynamic range and latitude
9

Dynamic range is the ev range of the sensor, latitude is how far off the ideal exposure you can be and still get a useful image. They are inextricably related, as a sensor with less dynamic range will have less latitude, one with a greater dynamic range will have more latitude.

Mr Garibaldi Contributing Member • Posts: 799
Re: Difference between dynamic range and latitude

stevo23 wrote:

The Davinator wrote:

Anyone have any thoughts on this? Had a few people lately claim they are the same despite the fact that definitions disagree. Thoughts?

I would have thought that exposure latitude is a film term and dynamic range is a digital term. They behave differently. With film, we wanted to see how much we could expose before losing highlights. There was no recovery, you just looked for a good soft knee. With digital, we recover highlights.

No?

When you run out of dynamic range, you have also run out of latitude.

stevo23 Forum Pro • Posts: 24,735
Re: Difference between dynamic range and latitude

Mr Garibaldi wrote:

stevo23 wrote:

The Davinator wrote:

Anyone have any thoughts on this? Had a few people lately claim they are the same despite the fact that definitions disagree. Thoughts?

I would have thought that exposure latitude is a film term and dynamic range is a digital term. They behave differently. With film, we wanted to see how much we could expose before losing highlights. There was no recovery, you just looked for a good soft knee. With digital, we recover highlights.

No?

When you run out of dynamic range, you have also run out of latitude.

I don't know if that does it for me in that it still doesn't give the sense of the difference between the two words. IE, we don't know what the latitude is until we know the DR of our scene vs. the DR of our camera. If we know that we have DR to spare for a given scene, we know our latitude. But in film talk, it always comes across differently than this.

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The Davinator
OP The Davinator Forum Pro • Posts: 24,707
Re: Difference between dynamic range and latitude

Yes.  Every definition I can find points to them being different, yet related.  I can find no definition anywhere that says they are not he same.

The Davinator
OP The Davinator Forum Pro • Posts: 24,707
Re: Difference between dynamic range and latitude
4

stevo23 wrote:

Mr Garibaldi wrote:

stevo23 wrote:

The Davinator wrote:

Anyone have any thoughts on this? Had a few people lately claim they are the same despite the fact that definitions disagree. Thoughts?

I would have thought that exposure latitude is a film term and dynamic range is a digital term. They behave differently. With film, we wanted to see how much we could expose before losing highlights. There was no recovery, you just looked for a good soft knee. With digital, we recover highlights.

No?

When you run out of dynamic range, you have also run out of latitude.

I don't know if that does it for me in that it still doesn't give the sense of the difference between the two words. IE, we don't know what the latitude is until we know the DR of our scene vs. the DR of our camera. If we know that we have DR to spare for a given scene, we know our latitude. But in film talk, it always comes across differently than this.

Every definition I can find shows DR as the whole range, and latitude being the amount above the middle grey that would create blown hightlights.  I can find nothing that says they are  the same

The Davinator
OP The Davinator Forum Pro • Posts: 24,707
Re: Difference between dynamic range and latitude

stevo23 wrote:

The Davinator wrote:

Anyone have any thoughts on this? Had a few people lately claim they are the same despite the fact that definitions disagree. Thoughts?

I would have thought that exposure latitude is a film term and dynamic range is a digital term. They behave differently. With film, we wanted to see how much we could expose before losing highlights. There was no recovery, you just looked for a good soft knee. With digital, we recover highlights.

No?

Possibly...but either way, no one would say they mean the same thing

beatboxa Veteran Member • Posts: 8,397
Re: Difference between dynamic range and latitude
4

The Davinator wrote:

Anyone have any thoughts on this? Had a few people lately claim they are the same despite the fact that definitions disagree. Thoughts?

Dynamic range is the difference between the sensor's max value (full saturation / clipping) and the minimum, where the noise is "unacceptable", or where the noise cannot be distinguished from the minimum signal.

Latitude is the amount you can push a signal to result in an acceptable rendering of a JPEG, which records a maximum of 8 stops of range (8-bit file), which represents 256 distinct shades of grey from black to white.

In other words, you will take a sensor's raw range and either slide it (push/pull) or compress it (localize contrast / "HDR") to fit within those 8 stops. Raw typically has closer to 12-14 bits, where 14 bits represents 16,000 shades (as opposed to JPEG's 256). When you shoot JPEG instead of raw, your camera is automatically doing this conversion / sliding / compression.

These are dependent concepts. If your sensor (and image) starts off with 10 stops of max range, you can only push your darkest shadows or brightest highlights (depending on the exposure) by about 2 stops. If your sensor does 14, you can push by about 6.

Here's a quick diagram that may help illustrate the relationship (not to scale).

  • Dynamic range = max brightness vs. minimum acceptable noise.
  • Latitude = how far you can push or pull to fit into the limited JPEG range.

A camera with worse dynamic range either cannot expose much (small sensor) or has high electronic noise, or both.  In either case, this limits how much latitude one has to push or pull.

ie. If the noise is higher, you can't brighten much because all you do is brighten noise.

stevo23 Forum Pro • Posts: 24,735
Re: Difference between dynamic range and latitude

The Davinator wrote:

stevo23 wrote:

Mr Garibaldi wrote:

stevo23 wrote:

The Davinator wrote:

Anyone have any thoughts on this? Had a few people lately claim they are the same despite the fact that definitions disagree. Thoughts?

I would have thought that exposure latitude is a film term and dynamic range is a digital term. They behave differently. With film, we wanted to see how much we could expose before losing highlights. There was no recovery, you just looked for a good soft knee. With digital, we recover highlights.

No?

When you run out of dynamic range, you have also run out of latitude.

I don't know if that does it for me in that it still doesn't give the sense of the difference between the two words. IE, we don't know what the latitude is until we know the DR of our scene vs. the DR of our camera. If we know that we have DR to spare for a given scene, we know our latitude. But in film talk, it always comes across differently than this.

Every definition I can find shows DR as the whole range, and latitude being the amount above the middle grey that would create blown hightlights. I can find nothing that says they are the same

Agreed. They are not the same - that much I'm convinced of. Latitude means you have room to spare before losing your highlights.

 stevo23's gear list:stevo23's gear list
Fujifilm X-Pro2 Fujifilm XF 60mm F2.4 R Macro Fujifilm XF 14mm F2.8 R Fujifilm XF 27mm F2.8 Fujifilm XF 23mm F1.4 R +3 more
stevo23 Forum Pro • Posts: 24,735
Re: Difference between dynamic range and latitude

beatboxa wrote:

The Davinator wrote:

Anyone have any thoughts on this? Had a few people lately claim they are the same despite the fact that definitions disagree. Thoughts?

Dynamic range is the difference between the sensor's max value (full saturation / clipping) and the minimum, where the noise is "unacceptable", or where the noise cannot be distinguished from the minimum signal.

Latitude is the amount you can push a signal to result in an acceptable rendering of a JPEG, which records a maximum of 8 stops of range (8-bit file), which represents 256 distinct shades of grey from black to white.

In other words, you will take a sensor's raw range and either slide it (push/pull) or compress it (localize contrast / "HDR") to fit within those 8 stops. Raw typically has closer to 12-14 bits, where 14 bits represents 16,000 shades (as opposed to JPEG's 256). When you shoot JPEG instead of raw, your camera is automatically doing this conversion / sliding / compression.

These are dependent concepts. If your sensor (and image) starts off with 10 stops of max range, you can only push your darkest shadows or brightest highlights (depending on the exposure) by about 2 stops. If your sensor does 14, you can push by about 6.

Here's a quick diagram that may help illustrate the relationship (not to scale).

  • Dynamic range = max brightness vs. minimum acceptable noise.
  • Latitude = how far you can push or pull to fit into the limited JPEG range.

A camera with worse dynamic range either cannot expose much (small sensor) or has high electronic noise, or both. In either case, this limits how much latitude one has to push or pull.

ie. If the noise is higher, you can't brighten much because all you do is brighten noise.

I don't think so mate, latitude isn't a term restricted to jpegs.

Dynamic range is the full range of your camera. Latitude is the amount of room you have in a given scene. If you have a 14 stop camera but a 7 stop scene, you have 7 stops of latitude for exposure. If you have a 14 stop camera and 18 stops of scene DR, you have no latitude and will have to adjust exposure down several stops to avoid blowing highlights.

It's similar in film as well - the maximum exposure at which an acceptable result is achieved minus the minimum result at which it is achieved gives the latitude. And with film, latitude is also influenced by a given film's non-linear curve.

 stevo23's gear list:stevo23's gear list
Fujifilm X-Pro2 Fujifilm XF 60mm F2.4 R Macro Fujifilm XF 14mm F2.8 R Fujifilm XF 27mm F2.8 Fujifilm XF 23mm F1.4 R +3 more
beatboxa Veteran Member • Posts: 8,397
Re: Difference between dynamic range and latitude
1

stevo23 wrote:

beatboxa wrote:

The Davinator wrote:

Anyone have any thoughts on this? Had a few people lately claim they are the same despite the fact that definitions disagree. Thoughts?

Dynamic range is the difference between the sensor's max value (full saturation / clipping) and the minimum, where the noise is "unacceptable", or where the noise cannot be distinguished from the minimum signal.

Latitude is the amount you can push a signal to result in an acceptable rendering of a JPEG, which records a maximum of 8 stops of range (8-bit file), which represents 256 distinct shades of grey from black to white.

In other words, you will take a sensor's raw range and either slide it (push/pull) or compress it (localize contrast / "HDR") to fit within those 8 stops. Raw typically has closer to 12-14 bits, where 14 bits represents 16,000 shades (as opposed to JPEG's 256). When you shoot JPEG instead of raw, your camera is automatically doing this conversion / sliding / compression.

These are dependent concepts. If your sensor (and image) starts off with 10 stops of max range, you can only push your darkest shadows or brightest highlights (depending on the exposure) by about 2 stops. If your sensor does 14, you can push by about 6.

Here's a quick diagram that may help illustrate the relationship (not to scale).

  • Dynamic range = max brightness vs. minimum acceptable noise.
  • Latitude = how far you can push or pull to fit into the limited JPEG range.

A camera with worse dynamic range either cannot expose much (small sensor) or has high electronic noise, or both. In either case, this limits how much latitude one has to push or pull.

ie. If the noise is higher, you can't brighten much because all you do is brighten noise.

I don't think so mate, latitude isn't a term restricted to jpegs.

Dynamic range is the full range of your camera. Latitude is the amount of room you have in a given scene. If you have a 14 stop camera but a 7 stop scene, you have 7 stops of latitude for exposure. If you have a 14 stop camera and 18 stops of scene DR, you have no latitude and will have to adjust exposure down several stops to avoid blowing highlights.

It's similar in film as well - the maximum exposure at which an acceptable result is achieved minus the minimum result at which it is achieved gives the latitude. And with film, latitude is also influenced by a given film's non-linear curve.

That's not how latitude is used in digital photography.  If you have a 7 stop scene and a 14-stop camera...

...and you underexpose by 14 stops, then you'll have far fewer than 7 stops of latitude... 

The keys to latitude are both in the camera's DR + where the exposure falls along the camera's DR.  If you're talking about latitude, at some point, you're going to take that raw DR and render it by compressing or shifting its DR--otherwise, there's no point in discussing latitude. 

So one reaction to this is ETTR:  if one ETTR's, one will have more latitude than if one exposes for JPEG because this will bring the darker shadows out of the camera's noisy region that limits DR.

You can also see this in DPReview's "Raw DR:  Exposure Latitude " tool:

Both DR & Exposure Latitude are contained in the same tool because these two are directly related.  This example shows what pushing 2 cameras' raw files by either 3 or 6 stops from RAW to JPEG looks like.

The Davinator
OP The Davinator Forum Pro • Posts: 24,707
Re: Difference between dynamic range and latitude
1

stevo23 wrote:

The Davinator wrote:

stevo23 wrote:

Mr Garibaldi wrote:

stevo23 wrote:

The Davinator wrote:

Anyone have any thoughts on this? Had a few people lately claim they are the same despite the fact that definitions disagree. Thoughts?

I would have thought that exposure latitude is a film term and dynamic range is a digital term. They behave differently. With film, we wanted to see how much we could expose before losing highlights. There was no recovery, you just looked for a good soft knee. With digital, we recover highlights.

No?

When you run out of dynamic range, you have also run out of latitude.

I don't know if that does it for me in that it still doesn't give the sense of the difference between the two words. IE, we don't know what the latitude is until we know the DR of our scene vs. the DR of our camera. If we know that we have DR to spare for a given scene, we know our latitude. But in film talk, it always comes across differently than this.

Every definition I can find shows DR as the whole range, and latitude being the amount above the middle grey that would create blown hightlights. I can find nothing that says they are the same

Agreed. They are not the same - that much I'm convinced of. Latitude means you have room to spare before losing your highlights.

I just thought it was odd that I had three guys telling me I was trying to redefine definitions....even though every defenition including those of DPReview writers disagreed with them.  I guess they were just trolling.

John Sheehy Forum Pro • Posts: 25,755
Re: Difference between dynamic range and latitude
1

stevo23 wrote:

The Davinator wrote:

Anyone have any thoughts on this? Had a few people lately claim they are the same despite the fact that definitions disagree. Thoughts?

I would have thought that exposure latitude is a film term and dynamic range is a digital term.

The basic idea is that latitude is recording medium DR minus scene DR. More DR therefore gives more latitude for the same scene.

They behave differently. With film, we wanted to see how much we could expose before losing highlights. There was no recovery, you just looked for a good soft knee. With digital, we recover highlights.

No?

Not really. There is no recovery in digital. What you call "recovery" just means not using high conversion contrast to hide shadow or highlight detail. RAW data could be handled just like the negative-film/negative-print process, but the ISO ratings would need to be much higher for digital, as it is orders of magnitude more sensitive to light.

Because of two factors: users want low ISOs, and early digital cameras had abysmal DR due to very high read noise, digital cameras start at low ISOs with minimal headroom, instead of higher ISOs with more headroom.

Any current camera with good DR that starts at ISO 100 could easily be redesigned so that it starts at ISO 3200 with 5 stops more headroom, with conversions that are much like negative/negative prints. People would rebel, however, and use radical ETTR, because unlike film, digital improves, rather than deteriorates, as you approach highest recordable exposure.

John Sheehy Forum Pro • Posts: 25,755
Re: Difference between dynamic range and latitude

The Davinator wrote:

Yes. Every definition I can find points to them being different, yet related. I can find no definition anywhere that says they are not he same.

They are the same, when your scene has no DR.

The Davinator
OP The Davinator Forum Pro • Posts: 24,707
Re: Difference between dynamic range and latitude

John Sheehy wrote:

The Davinator wrote:

Yes. Every definition I can find points to them being different, yet related. I can find no definition anywhere that says they are not he same.

They are the same, when your scene has no DR.

So shooting in a coal mine at night with the lens cap on would work....😜

fishy wishy
fishy wishy Veteran Member • Posts: 9,358
Re: Difference between dynamic range and latitude

They might as well be the same, because think of the Canons that were down two stops in dynamic range compared to the Sonys. If you tried to pull up the shadows you found problems so much sooner, i.e. in this instance poor dynamic range and poor latitude meant the same thing.

Of course you have to be a bit careful about latitude because you can't pull down highlights that were bleached to pure white and expect to achieve anything.

So although they do not technically mean exactly the same thing, they go so hand in hand that casually they might as well do.

John Sheehy Forum Pro • Posts: 25,755
Re: Difference between dynamic range and latitude

The Davinator wrote:

John Sheehy wrote:

The Davinator wrote:

Yes. Every definition I can find points to them being different, yet related. I can find no definition anywhere that says they are not he same.

They are the same, when your scene has no DR.

So shooting in a coal mine at night with the lens cap on would work....😜

Actually, no; such a scene can have plenty of DR. Scene DR has nothing to do with absolute light levels.

John Sheehy Forum Pro • Posts: 25,755
Re: Difference between dynamic range and latitude

stevo23 wrote:

Agreed. They are not the same - that much I'm convinced of. Latitude means you have room to spare before losing your highlights.

They can be spoken of as the same to some degree in the abstract (such as "DR is not just for scene DR; it is also exposure latitude") , but if you try to quantify them, then scene DR becomes part of the equation.

Mr Garibaldi Contributing Member • Posts: 799
Re: Difference between dynamic range and latitude
1

stevo23 wrote:

Mr Garibaldi wrote:

stevo23 wrote:

The Davinator wrote:

Anyone have any thoughts on this? Had a few people lately claim they are the same despite the fact that definitions disagree. Thoughts?

I would have thought that exposure latitude is a film term and dynamic range is a digital term. They behave differently. With film, we wanted to see how much we could expose before losing highlights. There was no recovery, you just looked for a good soft knee. With digital, we recover highlights.

No?

When you run out of dynamic range, you have also run out of latitude.

I don't know if that does it for me in that it still doesn't give the sense of the difference between the two words. IE, we don't know what the latitude is until we know the DR of our scene vs. the DR of our camera. If we know that we have DR to spare for a given scene, we know our latitude. But in film talk, it always comes across differently than this.

Certainly it gives a sense of the difference. What it doesn’t give, and cannot give, is a quantifiable difference because that is a moving target.

An older sensor with 7 stops of DR will have ample latitude in a scene with a 4 stop range, while a newer sensor with 12 stops of DR will not have any latitude in a scene with a 12 stop DR.

We saw the same thing with film. A low speed negative film had more latitude than a slide film, for example. The difference back then was that most of us weren’t carrying spot meters in the field or had status densitometers to measure the DR of a particular film. Now we all have this ability, and we seem to have developed a need to define things to the Nth degree before we will admit it exists, even when that sort of definition is impossible.

How long is a string? It’s an impossible question to answer in a quantifiable way, but this doesn’t mean string doesn’t exist.

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