Want to Increase The Dynamic Range of Your EOS 5D Mark IV Raw Files?

[Iliah Borg]

Some folks prefer Lumariver HDR ( http://www.lumariver.com ) because it results in DNG file with virtually no ghosting.

Unfortunately, its Mac only. I was really unhappy in 1992 when my company standardized on pc's, but I've become so adept at using one that a Mac might seem strange 25+ years later.

Ah. I'm sorry for forgetting to mention this limitation in my post.

 

[IglooEater]

So the (sub)photosites have some headroom in well capacity, being able to represent higher values before saturating than the ADC and post-ADC digital electronics. Basically the sensor has a ”native” ISO lower than 100.

No, they have half the well capacity, it is a maths issue.

If a 14 bit ADC had a range from 0-10, 10 being clipped, then if each half is below 5 the highlight will have detail in the main frame. If both sub pixels register 8 then in the main frame the value would be >10 so blown, but the value from the sub frame is 8, so it retains highlight detail.

The point is the main frame has the FWC of two sub pixels added together to make the output value limited at 14 bits, this means if the value of the sub frames pixel is less than 1/2 the 14 bit ceiling you will get additional highlight detail out of the sub frame. As we all know 1/2 or x2 is equal to 1 stop, so in theory there is a possible 1 stop improvement in highlight detail using this technique.

So could canon have given the sensor an extra stop of DR by using a 16 bit ADC? Edit: removed a dumb question

 

[privatebydesign]

So the (sub)photosites have some headroom in well capacity, being able to represent higher values before saturating than the ADC and post-ADC digital electronics. Basically the sensor has a ”native” ISO lower than 100.

No, they have half the well capacity, it is a maths issue.

If a 14 bit ADC had a range from 0-10, 10 being clipped, then if each half is below 5 the highlight will have detail in the main frame. If both sub pixels register 8 then in the main frame the value would be >10 so blown, but the value from the sub frame is 8, so it retains highlight detail.

The point is the main frame has the FWC of two sub pixels added together to make the output value limited at 14 bits, this means if the value of the sub frames pixel is less than 1/2 the 14 bit ceiling you will get additional highlight detail out of the sub frame. As we all know 1/2 or x2 is equal to 1 stop, so in theory there is a possible 1 stop improvement in highlight detail using this technique.

So could canon have given the sensor an extra stop of DR by using a 16 bit ADC? Edit: removed a dumb question

Yes. 14 bit files are holding Canon sensor capabilities back nowadays, more bit depth would realize more DR even with todays dual pixel sensors.

 

[Sporgon]

So the (sub)photosites have some headroom in well capacity, being able to represent higher values before saturating than the ADC and post-ADC digital electronics. Basically the sensor has a ”native” ISO lower than 100.

No, they have half the well capacity, it is a maths issue.

If a 14 bit ADC had a range from 0-10, 10 being clipped, then if each half is below 5 the highlight will have detail in the main frame. If both sub pixels register 8 then in the main frame the value would be >10 so blown, but the value from the sub frame is 8, so it retains highlight detail.

The point is the main frame has the FWC of two sub pixels added together to make the output value limited at 14 bits, this means if the value of the sub frames pixel is less than 1/2 the 14 bit ceiling you will get additional highlight detail out of the sub frame. As we all know 1/2 or x2 is equal to 1 stop, so in theory there is a possible 1 stop improvement in highlight detail using this technique.

So could canon have given the sensor an extra stop of DR by using a 16 bit ADC? Edit: removed a dumb question

Yes. 14 bit files are holding Canon sensor capabilities back nowadays, more bit depth would realize more DR even with todays dual pixel sensors.

But would 16 bit really make any practical difference ?

 

[privatebydesign]

So the (sub)photosites have some headroom in well capacity, being able to represent higher values before saturating than the ADC and post-ADC digital electronics. Basically the sensor has a ”native” ISO lower than 100.

No, they have half the well capacity, it is a maths issue.

If a 14 bit ADC had a range from 0-10, 10 being clipped, then if each half is below 5 the highlight will have detail in the main frame. If both sub pixels register 8 then in the main frame the value would be >10 so blown, but the value from the sub frame is 8, so it retains highlight detail.

The point is the main frame has the FWC of two sub pixels added together to make the output value limited at 14 bits, this means if the value of the sub frames pixel is less than 1/2 the 14 bit ceiling you will get additional highlight detail out of the sub frame. As we all know 1/2 or x2 is equal to 1 stop, so in theory there is a possible 1 stop improvement in highlight detail using this technique.

So could canon have given the sensor an extra stop of DR by using a 16 bit ADC? Edit: removed a dumb question

Yes. 14 bit files are holding Canon sensor capabilities back nowadays, more bit depth would realize more DR even with todays dual pixel sensors.

But would 16 bit really make any practical difference ?

If you look at the difference between some of the example images where there are clipped highlights, yes. Those of us that know how to wring out the very best from Canon sensors know we have to ETTR, having another stop of headroom is exactly how we can utilize that extra DR on a practical level on scenes that do have that DR range.

Do we need that extra stop most of the time? No we absolutely don't as many scenes simply don't have the DR to use it, but that doesn't mean we couldn't use it on the scenes that could need it.

My cameras, although being dual pixel, don't have the option of saving the dual format, but if I did I would shoot it in situations where the scene could use it.

 

[Sporgon]

So the (sub)photosites have some headroom in well capacity, being able to represent higher values before saturating than the ADC and post-ADC digital electronics. Basically the sensor has a ”native” ISO lower than 100.

No, they have half the well capacity, it is a maths issue.

If a 14 bit ADC had a range from 0-10, 10 being clipped, then if each half is below 5 the highlight will have detail in the main frame. If both sub pixels register 8 then in the main frame the value would be >10 so blown, but the value from the sub frame is 8, so it retains highlight detail.

The point is the main frame has the FWC of two sub pixels added together to make the output value limited at 14 bits, this means if the value of the sub frames pixel is less than 1/2 the 14 bit ceiling you will get additional highlight detail out of the sub frame. As we all know 1/2 or x2 is equal to 1 stop, so in theory there is a possible 1 stop improvement in highlight detail using this technique.

So could canon have given the sensor an extra stop of DR by using a 16 bit ADC? Edit: removed a dumb question

Yes. 14 bit files are holding Canon sensor capabilities back nowadays, more bit depth would realize more DR even with todays dual pixel sensors.

But would 16 bit really make any practical difference ?

If you look at the difference between some of the example images where there are clipped highlights, yes. Those of us that know how to wring out the very best from Canon sensors know we have to ETTR, having another stop of headroom is exactly how we can utilize that extra DR on a practical level on scenes that do have that DR range.

Do we need that extra stop most of the time? No we absolutely don't as many scenes simply don't have the DR to use it, but that doesn't mean we couldn't use it on the scenes that could need it.

My cameras, although being dual pixel, don't have the option of saving the dual format, but if I did I would shoot it in situations where the scene could use it.

I wasn't referring to the practical use of the theoretical one stop extra, but rather given current tech will 16 bit really realise that extra full stop ? Going from 14 bit to 16 bit is such a tiny fraction of an increase.

 

[snoke]

I wasn't referring to the practical use of the theoretical one stop extra, but rather given current tech will 16 bit really realise that extra full stop ? Going from 14 bit to 16 bit is such a tiny fraction of an increase.

16/14 = 1.14 - 14% increase
14% tiny?

This not real problem.
Real problem is more stops always highlight.
More stops never more shadow or dark.

 

[Sporgon]

I wasn't referring to the practical use of the theoretical one stop extra, but rather given current tech will 16 bit really realise that extra full stop ? Going from 14 bit to 16 bit is such a tiny fraction of an increase.

16/14 = 1.14 - 14% increase
14% tiny?

If you research bit depth you'll see why the move from 14 to 16 is very slight, just as 12 to 14 was. 8 to 12 was significant.

 

[BeenThere]

I wasn't referring to the practical use of the theoretical one stop extra, but rather given current tech will 16 bit really realise that extra full stop ? Going from 14 bit to 16 bit is such a tiny fraction of an increase.

16/14 = 1.14 - 14% increase
14% tiny?

This not real problem.
Real problem is more stops always highlight.
More stops never more shadow or dark.

I probably would not do it, but if you can add a stop of exposure to what you would normally use, then you have boosted the shadows by a stop.

 

[IglooEater]

I wasn't referring to the practical use of the theoretical one stop extra, but rather given current tech will 16 bit really realise that extra full stop ? Going from 14 bit to 16 bit is such a tiny fraction of an increase.

16/14 = 1.14 - 14% increase
14% tiny?

This not real problem.
Real problem is more stops always highlight.
More stops never more shadow or dark.

I probably would not do it, but if you can add a stop of exposure to what you would normally use, then you have boosted the shadows by a stop.

Well, not exactly. Practically yes, in that you can expose brighter and then pull from deeper in the shadows than before. Technically, your shadows stay the same relative to the brightness of the scene. It would be closer to having an iso 64 with better dr than iso 100. So you do have to expose brighter to get that extra shadow detail.

 

[IglooEater]

So could canon have given the sensor an extra stop of DR by using a 16 bit ADC? Edit: removed a dumb question

Yes. 14 bit files are holding Canon sensor capabilities back nowadays, more bit depth would realize more DR even with todays dual pixel sensors.

Thanks

While I’m asking, could Canon have resolved our parallax issue by writing both subframes instead of one subframe and the combine frames? I understand DPRAW was not built with that in mind, I’m just curious. Might one convert to 16 bit depth and average the two subframes?

 

[sebasan]

Maybe is a silly question, but, for the use of this feature, you have to take an exposure which blows the highlights of the picture by one stop, am I right?
Thanks.

 

[IglooEater]

Maybe is a silly question, but, for the use of this feature, you have to take an exposure which blows the highlights of the picture by one stop, am I right?
Thanks.

Yes. The goal here is achieving an extra stop of DR. That is achieved even without blowing the highlight. To actually use that extra DR one needs to blow the highlights 99% of a stop. It’s just the same as ETTR’ing, but actually going almost a stop too far deliberately.

 

[sebasan]

Maybe is a silly question, but, for the use of this feature, you have to take an exposure which blows the highlights of the picture by one stop, am I right?
Thanks.

Yes. The goal here is achieving an extra stop of DR. That is achieved even without blowing the highlight. To actually use that extra DR one needs to blow the highlights 99% of a stop. It’s just the same as ETTR’ing, but actually going almost a stop too far deliberately.

Thanks for the answer.