Tag: multiple images

What Constitutes an HDR Image?

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.