A Few Thoughts on Exposure & Tone Mapping – A Free Video

by George on May 16, 2013

Photograph © George A. Jardine

I created this video to help demystify the relationship between exposure values that are captured by your camera, and the brightness values they are mapped to during raw processing.

Please note that this video is an update of video #3 from the Image Correction Master Class. So if you’ve purchased that video series, you already have a (very slightly different) version of this video.

This free video can be found here.   –   TRT: 22:50  

{ 15 comments… read them below or add one }

Brian May 17, 2013 at 2:02 AM

What a great explanation, you truly make tone mapping understandable.
The graphics from the spread sheets take your explanation to another level.
Anyone who is working with photo’s on modern digital cameras will really benefit from watching this video.
Well done and thanks

david siegel May 18, 2013 at 7:36 PM

The incomparable George Jardine is at his best here, as always, helping us understand difficult topics, not just with clear language and examples but with excellent graphics. However you are doing digital photography, you can profit from his lessons – jump in!

Roger Walton May 19, 2013 at 12:42 PM

This is a superb explanation. I particularly like the references to HD curves and to the Zone System which, for me at least, help to make everything that much clearer.


Mike Nelson Pedde May 19, 2013 at 7:16 PM

Probably the simplest, most informative explanation of EV, histograms, tone curves, etc. I’ve yet come across. Makes a very complex subject easy to understand.



Barton May 21, 2013 at 10:14 PM

Thank you for all of your work in how tone mapping works. It is nice to see inside the camera and how it thinks and Lightroom.
very helpful.

Roger Walton May 24, 2013 at 3:20 AM

Having watched most of the new series I can only say WOW – great clear explanations – thanks for all your hard work on this.

Frank E May 24, 2013 at 4:43 PM

A thought provoking thank you for ‘A few thoughts on exposure and tone mapping’.
Lightroom 4 (and 5) or rather PV2012 continues to surprise – not just because it leaves more latitude generally and particularly for smoothing out the extreme ends of the tonal range as well as scope for ‘re-presenting’ highlight detail.
A working conclusion is that exposure needs to be adjusted not only to best ‘anchor’ the tonal map but also to compensate for ‘early’ highlight clipping in the in-camera based histogram – resulting from an inherently compromised JPEG based white balance.
Is a camera’s correct exposure to always be misleading? Anyone shooting RAW risks throwing data away if slavishly following in-camera metering and of course shooting JPEG jettisons both information and precludes post processing recovery. Put together with PV2012’s highlight processing it helps promote ’exposure to the right’.
How many stops to the right is the leading question? An image’s specific tonal range precludes over-exposure by prescription. Perhaps we stand to gain more by off centre wider bracketing? (I’d like to believe not and trust in PV2012.)
Oh and then there’s ‘image adaptive’ behaviour of PV2012’s algorithms and more subtleties particularly in mid tones. Where does clarity fit in?
Maybe someone should produce some educational videos on mastering these tools and controls. Gosh … it looks like you have …

George May 24, 2013 at 5:03 PM

The reason so-called ETTR is not mentioned in the video, is because I consider understanding the fundamentals of how EV’s are mapped to the tones you ultimately work with, to be vastly more interesting and useful when learning how to process your photos. And yes, the subsequent techniques for image correction that are drawn from that lesson, are indeed, built into nearly every video the new series. :-)


r. waller May 25, 2013 at 3:54 PM

Thank you for a very clear explaination of the tonal curve. I’m not a beginner, but I found a new and valuable understanding of the tonal curves un-uniform property.

Doug Johnson May 26, 2013 at 1:22 PM

Your video on exposure and tone mapping is superb! I’m so glad to now understand the guts of the zone system – in theory and practice – and how it is built into LR. Very clear explanation of “tone compression” in LR. Had not appreciated the evolution of LR in PV2012. The discussion is crystal clear and the charts and graphs make the story come alive. Terrific!

Have previously purchased several of your series. They compare very favorably with any training out there. Now looking forward to the Image Correction Master Class.

Jeremy August 15, 2013 at 4:41 PM

George thanks for the explanation. It really helps explain why ETTR (without clipping) will give you more tones to work with in post, especially considering the algorithm that LR uses to introduce more contrast on the upper and lower-most values. I’m looking forward to learning more in the Master Classes!

John Stevenson January 29, 2014 at 10:44 AM

hi George, I found this post only yesterday … (by following some of the links in your recent newsletter). Have done some similar work myself – given that the Lightroom Develop module shows up nowadays directly in Photoshop (as the ACR Filter). But I did not have the idea of making an exposure test pattern photographically. Rather I just lazily generated one in Photoshop itself. However, I did not restrict myself to just black and white (yes indeed – I realize that this is the Ansel Adams heritage situation, but he and Mr. Archer only had monochrome negatives to “play with” …).
There are some surprises when the primary and secondary colors are included in the test pattern – I can make a summary and send it to you if you wish.

Aidan Hornsby March 4, 2014 at 7:33 AM

Thanks so much for sharing this George.

I work for an educational technology company and am exposed to a large variety of different educational videos – many which follow the instructional screencast style.

Your tutorials are among the best I’ve seen for explaining complex,
technical subjects. Many instructors rush through content or don’t really
take full advantage of the visual nature of video. How you used the
different graphs and visuals in the tone mapping video really made the difference for me between grasping the gist of what’s being taught VS fundamentally understanding the concept.

Keep up the great work!

George March 5, 2014 at 10:39 AM

Thanks, Aidan! Very good to hear you enjoyed the video.

A mentor if mine once said, “Never tell what you can show”, and I’ve always tried to live by that in my writing and presentations. Photographers are visual people, and I always feel good illustrations help get the message across. In the case of the tone-mapping video, part of that exploration necessarily involves a bit of math, but in the end I couldn’t pair it back any further. But I think if you can stick with it eventually the points in the video will make it worth it.


Evan Anderman August 28, 2015 at 9:59 AM

Wow, this is the best explanation of the connection between exposure in the camera and processing using Lightroom that I have ever seen, thank you! Slowly making my way through the Develop Module videos and look forward to the Image Correction series next. I thought I knew how to use Lightroom but I hardly scratch the surface compared to your knowledge!

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