Expose to the Right: Proper use of the Histogram

lastdodobird · 02-05-2009, 01:12 AM

A friend recently told me that more often than not, you should expose your photos towards the right of the histogram.

Is this accurate?

And what are other histogram tips you guys can offer?

christinelandon · 02-05-2009, 01:21 AM

I just try to adjust EV compensation as needed to keep the histogram from crowding either the left or right side too hard. My K10D tends to "expose to the left," so evidently Pentax thinks protecting the highlights from blowing out is more important than getting the maximum tonal spread. I do find that it is easier in post processing to open up shadows than to recover blown highlights, so my EV compensation is rarely very radical...as I said, I just try to keep the tonal values from piling up at either a dark/left or bright/right distribution.

blende8 · 02-05-2009, 01:32 AM

A simple tip is to bracket:
Whenever you are unsure about the "correct" exposure, just take three shots (if possible) with +/-1 EV.
You can even make a moderate HDR from that.

PentaxPoke · 02-05-2009, 01:33 AM

Originally posted by lastdodobird

A friend recently told me that more often than not, you should expose your photos towards the right of the histogram.

Is this accurate?

Yes. You increase the signal to noise ratio on the sensor that way. Here are some test photos I took to demonstrate this a while ago:
Expose Right to reduce ISO noise test - a set on Flickr

1 stop increments were used for convenience. That way I was sure to end up with the exact same exposure level after processing.

Here are the pics just in case:

ISO 6400 Shot EV-1 (histogram to the left) and "pushed" 1 stop:

ISO 6400 Shot EV+1 (histogram to the right) and "pulled" 1 stop. Note the significant improvement in noise even though the exposure level is exactly the same.

No question exposing to the right is better huh? The key is to make sure you don't expose so far right that you "clip" the highlights. Here is a nice article on the subject: http://www.luminous-landscape.com/tutorials/expose-right.shtml

Last edited by PentaxPoke; 02-05-2009 at 01:48 AM.

David Glazebrook · 02-05-2009, 04:03 AM

as far to the right as not to clip your highlights. Ive been told that there is more info in the top half of the histogram than the bottom meaning more room to PP. Always easier to darken than try to lighten an image an get lots of noise.

**Lowell Goudge** · 02-05-2009, 05:34 AM

there is no simple rule

it depends on the composition of the image, and the detail that you want to show.

the use of the histogram is to give you an indication of how the exposure is distributed ovr the entire frame. a darker subkect (percentage of the frame) will be to the left, a lighter one to the right.

pingflood · 02-05-2009, 06:05 AM

Lowell,

That is very true, but they are mostly talking about maximizing the captured data rather than giving a "correct" exposure out of the box. Exposing to the right usually means additional post processing.

lastdodobird · 02-05-2009, 07:42 AM

Wow thanks for the info so far and that was quite useful info PentaxPoke

**Lowell Goudge** · 02-05-2009, 09:26 PM

Originally posted by pingflood

Lowell,

That is very true, but they are mostly talking about maximizing the captured data rather than giving a "correct" exposure out of the box. Exposing to the right usually means additional post processing.

Perhaps, but that depends on whether the "maximum data" you want to capture is in the light area, or the dark area (assuming divided scene).

As I said. you need to decide exactly what is "important data" not just maximum data

Edit note. I guess then on a starlit night they should expose the black emptyness of space to grey? just kidding

philbaum · 02-05-2009, 11:39 PM

Another tip,

Going to the menu and moving the contrast to a smaller band when its difficult to get the high contrast scene all on the histogram. I've started finally taking advantage of that and it helps.

Phil

dlacouture · 02-06-2009, 01:45 AM

Well, the problem is also that the histogram is computed from the JPEG preview, not the RAW data...
So it's greatly dependent on your settings (contrast, saturation, and so on...), and so any indication it can give will be in fact slightly false...

This can be easily demonstrated with near-white subjects : histogram will show burned areas, but in fact the data is still here in RAW.

**Lowell Goudge** · 02-06-2009, 05:55 AM

Originally posted by dlacouture

Well, the problem is also that the histogram is computed from the JPEG preview, not the RAW data...
So it's greatly dependent on your settings (contrast, saturation, and so on...), and so any indication it can give will be in fact slightly false...

This can be easily demonstrated with near-white subjects : histogram will show burned areas, but in fact the data is still here in RAW.

regardless of JPEG or RAW, if you are in the near white zone of the photo (assuming there are also dark areas and normal areas, the data is very compressed.

The only real difference is that you are dealing with 12 bit in raw and 8 bit in JPEG, and as a result you do start to lose definition sooner, but you do lose it in both.

But to be honest, if you are shooting raw only to get the data out of that area, you should be shooting with different settings

pingflood · 02-06-2009, 06:30 AM

Originally posted by Lowell Goudge

Perhaps, but that depends on whether the "maximum data" you want to capture is in the light area, or the dark area (assuming divided scene).

As I said. you need to decide exactly what is "important data" not just maximum data

Edit note. I guess then on a starlit night they should expose the black emptyness of space to grey? just kidding

Nope, because they'd blow out the stars.

You are correct that if there's a wide range of light levels in the scene you have to pick what to sacrifice. But if you have the headroom to up exposure without losing highlights, you will have more data to work with if you push it as far as you can and then adjust down in post.

**jbinpg** · 02-06-2009, 08:47 AM

You might be able to drag back about 1.5- 2 stops of overexposure in the highlights with RAW PP but there are no miracles. Too blown highlights are gone forever.

Wheatfield · 02-06-2009, 09:08 AM

Originally posted by jbinpg

You might be able to drag back about 1.5- 2 stops of overexposure in the highlights with RAW PP but there are no miracles. Too blown highlights are gone forever.

A lot of this discussion seems to presume that if you expose to the right, you are going to lose highlight data. This is just simply not true. Most scenes will fit well within the DR of the camera.
Were this not the case, slide film would never have worked, since digital sensors have a several stop longer range than slide film ever had.
If you expose to the right, then the entire scene range is being moved up the scale and away from the noise base.
This is a good thing, since it gives cleaner shadows when you bring the exposures down in post.
As long as nothing is clipped, then no highlight detail has been lost.
While the same thing could be said of the left side of the histogram, as you get closer to the low end of the DR, you are getting a mix of noise and detail, which is a bad thing, since often noise reduction will then kill whatever shadow detail was there.

02-05-2009, 01:12 AM	#1
lastdodobird Senior Member Join Date: Oct 2007 Posts: 128	Expose to the Right: Proper use of the Histogram A friend recently told me that more often than not, you should expose your photos towards the right of the histogram. Is this accurate? And what are other histogram tips you guys can offer?

02-05-2009, 01:32 AM	#3
blende8 Veteran Member Join Date: Feb 2007 Location: Bremen, Germany Photos: Albums Posts: 1,521	Bracketing A simple tip is to bracket: Whenever you are unsure about the "correct" exposure, just take three shots (if possible) with +/-1 EV. You can even make a moderate HDR from that.

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02-05-2009, 01:21 AM	#2
christinelandon Veteran Member Join Date: Jan 2008 Location: Seattle, Washington, USA Photos: Gallery Posts: 812	I just try to adjust EV compensation as needed to keep the histogram from crowding either the left or right side too hard. My K10D tends to "expose to the left," so evidently Pentax thinks protecting the highlights from blowing out is more important than getting the maximum tonal spread. I do find that it is easier in post processing to open up shadows than to recover blown highlights, so my EV compensation is rarely very radical...as I said, I just try to keep the tonal values from piling up at either a dark/left or bright/right distribution.

02-05-2009, 01:33 AM	#4
PentaxPoke Veteran Member Join Date: Jan 2008 Location: Oklahoma Posts: 1,411	Originally posted by lastdodobird A friend recently told me that more often than not, you should expose your photos towards the right of the histogram. Is this accurate? Yes. You increase the signal to noise ratio on the sensor that way. Here are some test photos I took to demonstrate this a while ago: Expose Right to reduce ISO noise test - a set on Flickr 1 stop increments were used for convenience. That way I was sure to end up with the exact same exposure level after processing. Here are the pics just in case: ISO 6400 Shot EV-1 (histogram to the left) and "pushed" 1 stop: ISO 6400 Shot EV+1 (histogram to the right) and "pulled" 1 stop. Note the significant improvement in noise even though the exposure level is exactly the same. No question exposing to the right is better huh? The key is to make sure you don't expose so far right that you "clip" the highlights. Here is a nice article on the subject: http://www.luminous-landscape.com/tutorials/expose-right.shtml Last edited by PentaxPoke; 02-05-2009 at 01:48 AM.

02-05-2009, 04:03 AM	#5
David Glazebrook Senior Member Join Date: Mar 2007 Location: Blue Mountains, NSW Photos: Gallery Posts: 217	as far to the right as not to clip your highlights. Ive been told that there is more info in the top half of the histogram than the bottom meaning more room to PP. Always easier to darken than try to lighten an image an get lots of noise.

02-05-2009, 05:34 AM	#6
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,888	there is no simple rule it depends on the composition of the image, and the detail that you want to show. the use of the histogram is to give you an indication of how the exposure is distributed ovr the entire frame. a darker subkect (percentage of the frame) will be to the left, a lighter one to the right.

02-05-2009, 06:05 AM	#7
pingflood Veteran Member Join Date: Jun 2008 Location: Borås, Sweden Photos: Gallery Posts: 3,169	Lowell, That is very true, but they are mostly talking about maximizing the captured data rather than giving a "correct" exposure out of the box. Exposing to the right usually means additional post processing.

02-05-2009, 07:42 AM	#8
lastdodobird Senior Member Join Date: Oct 2007 Posts: 128 Original Poster	Wow thanks for the info so far and that was quite useful info PentaxPoke

02-05-2009, 09:26 PM	#9
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,888	Originally posted by pingflood Lowell, That is very true, but they are mostly talking about maximizing the captured data rather than giving a "correct" exposure out of the box. Exposing to the right usually means additional post processing. Perhaps, but that depends on whether the "maximum data" you want to capture is in the light area, or the dark area (assuming divided scene). As I said. you need to decide exactly what is "important data" not just maximum data Edit note. I guess then on a starlit night they should expose the black emptyness of space to grey? just kidding

02-05-2009, 11:39 PM	#10
philbaum Veteran Member Join Date: Oct 2007 Location: Port Townsend, Washington State, USA Posts: 3,659	Another tip, Going to the menu and moving the contrast to a smaller band when its difficult to get the high contrast scene all on the histogram. I've started finally taking advantage of that and it helps. Phil

02-06-2009, 01:45 AM	#11
dlacouture Veteran Member Join Date: Jul 2008 Location: Var, South of France Photos: Albums Posts: 1,074	Well, the problem is also that the histogram is computed from the JPEG preview, not the RAW data... So it's greatly dependent on your settings (contrast, saturation, and so on...), and so any indication it can give will be in fact slightly false... This can be easily demonstrated with near-white subjects : histogram will show burned areas, but in fact the data is still here in RAW.

02-06-2009, 05:55 AM	#12
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,888	Originally posted by dlacouture Well, the problem is also that the histogram is computed from the JPEG preview, not the RAW data... So it's greatly dependent on your settings (contrast, saturation, and so on...), and so any indication it can give will be in fact slightly false... This can be easily demonstrated with near-white subjects : histogram will show burned areas, but in fact the data is still here in RAW. regardless of JPEG or RAW, if you are in the near white zone of the photo (assuming there are also dark areas and normal areas, the data is very compressed. The only real difference is that you are dealing with 12 bit in raw and 8 bit in JPEG, and as a result you do start to lose definition sooner, but you do lose it in both. But to be honest, if you are shooting raw only to get the data out of that area, you should be shooting with different settings

02-06-2009, 06:30 AM	#13
pingflood Veteran Member Join Date: Jun 2008 Location: Borås, Sweden Photos: Gallery Posts: 3,169	Originally posted by Lowell Goudge Perhaps, but that depends on whether the "maximum data" you want to capture is in the light area, or the dark area (assuming divided scene). As I said. you need to decide exactly what is "important data" not just maximum data Edit note. I guess then on a starlit night they should expose the black emptyness of space to grey? just kidding Nope, because they'd blow out the stars. You are correct that if there's a wide range of light levels in the scene you have to pick what to sacrifice. But if you have the headroom to up exposure without losing highlights, you will have more data to work with if you push it as far as you can and then adjust down in post.

02-06-2009, 08:47 AM	#14
jbinpg Site Supporter Join Date: Mar 2008 Location: Prince George, BC Photos: Gallery \| Albums Posts: 3,546	You might be able to drag back about 1.5- 2 stops of overexposure in the highlights with RAW PP but there are no miracles. Too blown highlights are gone forever.

02-06-2009, 09:08 AM	#15
Wheatfield Moderator Join Date: Apr 2008 Location: The wheatfields of Canada Posts: 15,981	Originally posted by jbinpg You might be able to drag back about 1.5- 2 stops of overexposure in the highlights with RAW PP but there are no miracles. Too blown highlights are gone forever. A lot of this discussion seems to presume that if you expose to the right, you are going to lose highlight data. This is just simply not true. Most scenes will fit well within the DR of the camera. Were this not the case, slide film would never have worked, since digital sensors have a several stop longer range than slide film ever had. If you expose to the right, then the entire scene range is being moved up the scale and away from the noise base. This is a good thing, since it gives cleaner shadows when you bring the exposures down in post. As long as nothing is clipped, then no highlight detail has been lost. While the same thing could be said of the left side of the histogram, as you get closer to the low end of the DR, you are getting a mix of noise and detail, which is a bad thing, since often noise reduction will then kill whatever shadow detail was there.