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MNS Photo Special Interest Group
High Dynamic Range Photography
by
Stewart Forbes
Friday, April 29, 2011
High Dynamic Range (HDR) Photography
Friday, April 29, 2011
What Is HDR?
High Dynamic Range photography is a method of combining a number of differently exposed photos to generate one photograph with a very wide exposure range containing detail in both highlights and deep shadows.
Friday, April 29, 2011
Why do we need HDR?
• The dynamic range of sensors used in digital photography is many times less than that of the human eye and generally not as wide as that of chemical photographic media.
• The human eye can perceive a greater dynamic range than is ordinarily possible with a camera. Where our pupil opens and closes for varying light, our eyes can see over a range of nearly 24 f-stops.
• On the other hand, for accurate comparisons with a single photo (at constant aperture, shutter and ISO), we can only consider the instantaneous dynamic range (where our pupil opening is unchanged) and most estimate anywhere from 10-14 f-stops.
Friday, April 29, 2011
Why do we need HDR?
Item Stops Contrast
Top DSLR Camera 11 2048:1
Computer LCD 9.5 700:1
Print Film 7 128:1
Friday, April 29, 2011
But do we really need HDR?
“In many ways, Photoshop CS2's HDR function is the holy grail of dynamic range. With properly shot and processed files it allows photographers to easily create images that were previously impossible, or at least very difficult to accomplish. But, good as it is, like a gun or nuclear power, it can be a force for evil as well as good.Not every image needs to have 10-15 stops of dynamic range. In fact, most photographs look quite nice, with the 5-7 stops of dynamic range that we're used to. I fully expect to see some really silly if not downright ugly images in the months ahead, as photographers start discovering what the HDR function in CS2 is capable of.But, as with all such tools, in the hands of sensitive artists and competent craftsmen, I'm sure that we will start to be shown the world in new and exciting ways”.
– Michael Reichmann, Luminous Landscape (2005)
Friday, April 29, 2011
How do we achieve HDR?
• High-dynamic-range photographs are generally achieved by capturing multiple standard photographs, often using exposure bracketing, and then merging them into an HDR image.
• Digital photographs are often encoded in a camera's raw image format, because 8 bit JPEG encoding doesn't offer enough values to allow fine transitions (and also introduces undesirable effects due to the lossy compression).
• Any camera that allows manual over- or under-exposure of a photo can be used to create HDR images.
Friday, April 29, 2011
Creating an HDR photograph
Friday, April 29, 2011
-4 stops
Creating an HDR photograph
Friday, April 29, 2011
-4 stops -2 stops
Creating an HDR photograph
Friday, April 29, 2011
-4 stops -2 stops
+2 stops
Creating an HDR photograph
Friday, April 29, 2011
-4 stops -2 stops
+2 stops +4 stops
Creating an HDR photograph
Friday, April 29, 2011
-4 stops -2 stops
+2 stops +4 stops
Creating an HDR photograph
Friday, April 29, 2011
Kellieʼs Castle, Perak
Friday, April 29, 2011
Kellieʼs Castle, Perak
Friday, April 29, 2011
Kellieʼs Castle, Perak
Friday, April 29, 2011
Kellieʼs Castle, Perak
Friday, April 29, 2011
Kellieʼs Castle, Perak
Friday, April 29, 2011
Some more less dramatic HDRs
Friday, April 29, 2011
Some more less dramatic HDRs
Friday, April 29, 2011
Some more less dramatic HDRs
Friday, April 29, 2011
Conclusions
• HDR is not difficult even with compact cameras
• HDR is becoming mainstream as a method to extend the dynamic range (contrast ratio) of even fairly ordinary photographs.
• HDR can be misused but also can give a new insight into many images
Friday, April 29, 2011
Other Useful Post Process Techniques for use with Panoramas
• Cropping
• Exposure level adjustments
• Image repair or modification
• VR processing
Friday, April 29, 2011
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