Tag: tone mapping

What Constitutes an HDR Image?

Posted on by Nick Roberts

I’m often asked what is HDR photography? HDR simply stated means High Dynamic Range. The impetus behind HDR is to reveal detail in all ranges of the exposure. It drives me crazy when people say that the only way to create HDR is by combining multiple images. Digital sensors are capable of a much broader exposure latitude than film; they can record so much information that was unavailable with film allowing us to create a broad range of tonality from light to dark within a single frame.

To my way of thinking HDR means being able to bring out detail in both shadow and highlight areas in a photo. Granted there are times, a strong backlight or a subject in deep shadow, when the exposure range is so great that combining a range of exposures is the only way to attain that goal but as long as the histogram/exposure is within the range of the sensor there is enough information in a single frame to create HDR. It is not any different that dodging and burning when you boil it down.

I remember my “ah-ha” moment in the darkroom eons ago when I had a negative that was severely underexposed in the shadows and my instructor explained that through dodging and burning I could extract the info that was there and create the image I thought I had taken. I was expanding the dynamic range beyond what a single exposure would produce, going straight from the negative through the enlarger, simply by burning in the underexposed shadows while dodging the overexposed highlights to tone map the image. Isn’t that the essence of Ansel Adams’ zone system? He exposed for as broad a range of tones as his film would record and then completed the image in the darkroom dodging and burning areas of the image to produce an image that had the full range of tones from pure black through pure white.

When folks refer to an image today as HDR I think what they are actually referring to is the stylization of the image. The emphasis is on enhancing not only the range of exposure but also enhancement of the saturation, hues and tints within the image along with increased contrast and sharpening. Sometimes the only way to accomplish those goals is through combining multiple exposures but simply combining multiple exposures usually results in a very flat image with very little contrast. It doesn’t become what is commonly referred to as an “HDR” until it has been tone mapped which, to my way of thinking, menas stylized through processing to attain the photographer’s vision for the photo. Taking this a step further I would argue that a single frame can be tone mapped and stylized to create what is referred to today as HDR photography.

Waterfront Park Afternoon

Posted on by Nick Roberts
Waterfront Park Afternoon
Waterfront Park Afternoon

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This image was processed in Aperture 3 as a RAW file before being taken into NIK HDR Efex 2 where I used the Structure 1 preset where I then boosted exposure, shadows, highlights, contrast and structure. I then returned the image to Aperture 3 where I boosted definition, contrast and vibrancy followed by sharpening.

Spaghetti Junction Sky

Posted on by Nick Roberts
Spaghetti Junction Sky
Spaghetti Junction Sky

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The point where the three Interstate Highways intersect in Louisville is known locally as Spaghetti Junction. The weather was changing yesterday from a cloudless sky in the morning to this winter sky around mid afternoon. This image overlooks the Spaghetti Junction intersection and southeast Louisville. It appeared that there was a grid that had been overlaid on the city sky that extended into infinity. The perspective of the clouds intrigued me and I decided to capture it.

I first processed this image in Aperture 3 where I made a few adjustments to the RAW file before taking it into NIK HDR Efex Pro 2 where I worked on enhancing the texture and tonality of the image. I then returned it to Aperture 3 where I applied some exposure, saturation and vibrancy changes. I lowered the saturation slightly and increased the vibrancy in order to achieve the overall feeling I felt when I shot the scene. I had a couple of dust spots that needed attention so I used the Spot and Patch tool in Aperture 3 to clean them up. I then took the image into Photoshop CS5 where I manually adjusted the vertical perspective to compensate for the distortion my 12mm lens had created. Back in Aperture 3 I applied a very slight vignette before saving the image for the web.

Rivets and Rust

Posted on by Nick Roberts
Rivets and Rust
Rivets and Rust

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Last month I read an interesting book,  The Photographer’s Eye by Michael Freeman , which is a fantastic book on the subject of composition. In one chapter Freeman discusses the many possibilities that often lie within a single frame. He points out how by selectively cropping the image the photograph can be used to tell several different stories.

I decided to take the image I posted this morning, Perry and Thomas, and see what other ways I could use it. By cropping the figures from the left side of the frame I was able to create an entirely different image that speaks to texture, color and composition without any visible human involvement.