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Old 16th November 2015
Jim Ford Jim Ford is offline
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Expose to the Right of the Histogram!

Page 7 of "Camera Raw with Adobe Photoshop CS2" by the late-great Bruce Fraser* states:

"Correct exposure is at least as important with digital capture as it is with film, but correct exposure in the digital realm means keeping the highlights as close to blowing out without actually doing so, as possible. If you fall to the temptation to underexpose images to avoid blowing out the highlights, you'll waste a lot of the bits the camera can capture, and you'll run a significant risk of introducing noise in the midtones and shadows. If you overexpose, you may blow out the highlights, but one of the great things about the Camera Raw plug-in is its ability to recover highlight detail" ... "so if you're going to err on one side or the other, it's better to err on the side of slight overexposure."

* So who's Bruce Fraser? He was an internationally recognised authority on digital imaging and colour reproduction and an author of many books on the subject. He is in the 'Adobe Hall of Fame' and the inventor of the colour management system used today in digital image reproduction.

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Old 16th November 2015
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Re: Expose to the Right of the Histogram!

It really does work and is a technique that I always try to achieve.
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Old 16th November 2015
Ricoh Ricoh is offline
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Re: Expose to the Right of the Histogram!

I have not heard of this before but it sounds like some form of an algorithmic guessing game, since once the well is full, there's no way for the electronics to determine the degree of clipping. 1x, 1.1x ...10x, or any other value. Some form of interpolation based on neighbouring pixels, maybe.
If someone knows better, please pipe up, I'm more than intrigued.
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Old 16th November 2015
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Re: Expose to the Right of the Histogram!

Quote:
Originally Posted by Ricoh View Post
I have not heard of this before but it sounds like some form of an algorithmic guessing game, since once the well is full, there's no way for the electronics to determine the degree of clipping. 1x, 1.1x ...10x, or any other value. Some form of interpolation based on neighbouring pixels, maybe.
If someone knows better, please pipe up, I'm more than intrigued.
There is no way of escaping the fact that once the highlights are blown, they are blown. However, in practice raw files (especially from latest generation sensors) have quite a wide margin for retaining detail, which can be pulled back in processing, from highlights that at the time of capture the camera indicated were overexposed. It takes practice to accurately judge how much indicated overexposure you can get away with before the data becomes irretrievable, but when you get it right it makes full use of the dynamic range of your camera's sensor. Of course, if you are photographing fairly static subjects you can hedge your bets by exposure bracketing.
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Old 16th November 2015
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Re: Expose to the Right of the Histogram!

One of the wonders of modern digital cameras is the live histogram. This, together with centre weight exposure and aperture priority is part of my standard camera setup. I could do without a lot of the other junk in the viewfinder, but I like to make room for the histogram...
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Old 16th November 2015
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Re: Expose to the Right of the Histogram!

Quote:
Originally Posted by Ricoh View Post
I have not heard of this before but it sounds like some form of an algorithmic guessing game, since once the well is full, there's no way for the electronics to determine the degree of clipping. 1x, 1.1x ...10x, or any other value. Some form of interpolation based on neighbouring pixels, maybe.
If someone knows better, please pipe up, I'm more than intrigued.
You are assuming that clipping occurs at the sensor photo sites.This would only be the case with a monochrome sensor.

Our cameras have sensors with a Bayer Filter in front of them to give colour. Individual photo sites see only Red, Green or Blue and there are twice as many Green photosites as Red or Blue to mimic the physiology of the human eye. The Green photosites are used to produce the Luminance channel in the image pixel as well as contributing to the colour of each pixel. To generate an image pixel interpolation between the data (after analogue to digital conversion) from surrounding photosites is used (in raw convesion) to produce the colour for each pixel. Since there is twice as much data available for the luminance channel (and this is at up to 16 bits deep) there is some latitude to recover highlights in raw conversion. As John indicates this will not work with grossly overexposed images. This is one of the reasons that "shooting raw" can be beneficial.

For more detailed information see : https://en.wikipedia.org/wiki/Raw_image_format

And :https://en.wikipedia.org/wiki/Bayer_filter

Regards.
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Old 17th November 2015
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Re: Expose to the Right of the Histogram!

i think the latitude thing is a limit issue, or rather not reaching limit but just a smidgin below. If both luminance sites fill to capacity, or overfill, the games is over irrespective of the processing upstream, whether there's 16 bits of data or an infinite number of bits of data. With twice the number of green luminance sites it assumes an even distribution of photons, but who knows.
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Old 17th November 2015
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Re: Expose to the Right of the Histogram!

Quote:
Originally Posted by Ricoh View Post
I have not heard of this before but it sounds like some form of an algorithmic guessing game, since once the well is full, there's no way for the electronics to determine the degree of clipping. 1x, 1.1x ...10x, or any other value. Some form of interpolation based on neighbouring pixels, maybe.
If someone knows better, please pipe up, I'm more than intrigued.
Quote:
Originally Posted by Zuiko View Post
There is no way of escaping the fact that once the highlights are blown, they are blown. However, in practice raw files (especially from latest generation sensors) have quite a wide margin for retaining detail, which can be pulled back in processing, from highlights that at the time of capture the camera indicated were overexposed. It takes practice to accurately judge how much indicated overexposure you can get away with before the data becomes irretrievable, but when you get it right it makes full use of the dynamic range of your camera's sensor. Of course, if you are photographing fairly static subjects you can hedge your bets by exposure bracketing.
That's true of the camera models with the latest sensors such as E-M5 onwards (as you have also indicated) but the earlier models with the 12MP Panasonic sensor (& also a camera such as the Stylus 1) does not have the luxury of having that extra headroom (or much of it) within the raw file & therefore extra care needs to be taken not to blow the highlights (where it matters) but at the same time not to expose to the left either to maximise the detail possible from the exposure. That's my opinion anyhow. I would agree with the AE bracketing, something I should use occasionally.
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Old 17th November 2015
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Re: Expose to the Right of the Histogram!

It's a technique I have been using for years, I was put onto it by an article on the Luminous Landscape.
Like Pete says, use the live histogram, that's what it for, to enable you to control the exposure avoiding clipping but allowing maximum exposure. Every shot I take the exposure is set by me looking at the live histogram and altering the exposure with the thumbwheel. It's an excellent technique to use when photographing scenes with very bright sections such as a bright sky, the camera averages the exposure and leaves it sometimes very under exposed, watching the histogram you can wind up the exposure, sometimes as much as 2 stops without blowing anything out but get a lot more shadow detail and reduce the noise of the shadows too and get the actual subject correctly exposed.

One thing to keep in mind though, there are different considerations when shooting RAW or jpg's, with RAW push it to the limit then bring the exposure back in post processing, with jpg's the image is already "cooked" and can't be adjusted very much so you expose to get the actual subject exposed correctly.

Paul
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Old 17th November 2015
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Re: Expose to the Right of the Histogram!

Quote:
Originally Posted by Ross the fiddler View Post
That's true of the camera models with the latest sensors such as E-M5 onwards (as you have also indicated) but the earlier models with the 12MP Panasonic sensor (& also a camera such as the Stylus 1) does not have the luxury of having that extra headroom (or much of it) within the raw file & therefore extra care needs to be taken not to blow the highlights (where it matters) but at the same time not to expose to the left either to maximise the detail possible from the exposure. That's my opinion anyhow. I would agree with the AE bracketing, something I should use occasionally.
Yes, with older sensors you can still use the technique but you do have to be a little more conservative.
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Old 17th November 2015
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Re: Expose to the Right of the Histogram!

Yes, this is a really important way to maximise the performance of cameras with smaller sensors (as is filling the frame to minimise cropping, for another example).

We had a talk from a Sony ambassador at our camera club a couple of weeks ago who got talking about this area, and made the point that on the Sony mirrorless full frame bodies you need to set the in-camera jpeg to be fully 'flat' in order to use the VF histogram accurately for raw images.

In other words, the camera uses your jpeg settings to display the histogram so it doesn't clip jpegs, which makes sense.

I have no idea whether this is also true for Oly since I almost never shoot jpeg and always have everything set to 'off' or 'natural' anyway, but I thought it worth mentioning.
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Old 17th November 2015
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Re: Expose to the Right of the Histogram!

I should also have quoted from page 6 of the same book:

"When a camera captures six stops of dynamic range (which is fairly typical of today's digital SLRs *), half of the 4,096 levels are devoted to the brightest stop, half of the remainder (1,024 levels) are devoted to the next stop, half of the remainder (512 levels) are devoted to the next stop, and so on. The darkest stop, the extreme shadows, is represented by only 64 levels"

* 2005

The surprising thing about the above is that if we don't pay attention to the exposure histogram, we may not capture a lot of the available data. Say we set the exposure for a scene such that the highlight end of the histogram is just touching the RHS. If we then adjust the exposure down just one stop, we will only capture half the data that we would have done with the initial setting!



Jim
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Re: Expose to the Right of the Histogram!

Quote:
Originally Posted by Zuiko View Post
Yes, with older sensors you can still use the technique but you do have to be a little more conservative.
As I discovered with the limits of the Stylus 1 (still using JPEG plus RAW).
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Old 17th November 2015
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Re: Expose to the Right of the Histogram!

Quote:
Originally Posted by Jim Ford View Post
I should also have quoted from page 6 of the same book:

"When a camera captures six stops of dynamic range (which is fairly typical of today's digital SLRs *), half of the 4,096 levels are devoted to the brightest stop, half of the remainder (1,024 levels) are devoted to the next stop, half of the remainder (512 levels) are devoted to the next stop, and so on. The darkest stop, the extreme shadows, is represented by only 64 levels"

* 2005

The surprising thing about the above is that if we don't pay attention to the exposure histogram, we may not capture a lot of the available data. Say we set the exposure for a scene such that the highlight end of the histogram is just touching the RHS. If we then adjust the exposure down just one stop, we will only capture half the data that we would have done with the initial setting!



Jim
Thanks, Jim, that's a really important point.
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Old 17th November 2015
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Re: Expose to the Right of the Histogram!

Quote:
Originally Posted by Jim Ford View Post
I should also have quoted from page 6 of the same book:

"When a camera captures six stops of dynamic range (which is fairly typical of today's digital SLRs *), half of the 4,096 levels are devoted to the brightest stop, half of the remainder (1,024 levels) are devoted to the next stop, half of the remainder (512 levels) are devoted to the next stop, and so on. The darkest stop, the extreme shadows, is represented by only 64 levels"

* 2005

The surprising thing about the above is that if we don't pay attention to the exposure histogram, we may not capture a lot of the available data. Say we set the exposure for a scene such that the highlight end of the histogram is just touching the RHS. If we then adjust the exposure down just one stop, we will only capture half the data that we would have done with the initial setting!



Jim
This is something I always tell people, as it is often overlooked

I also refer to: http://www.cambridgeincolour.com/tut...techniques.htm as being a useful guide.
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