The motion distortion effect...

The most interesting aspect of scanner photography is the fact that movement is recorded much differently than it is with conventional photography. Objects being photographed, if still, are recorded fairly conventionally. Objects that are moving, however, are stretched and distorted, pulled and twisted into new and unique forms that, at first, seem to be pure distortion. These distortions are not random, nor are they meaningless. With a proper understanding of how a scanner photograph works, they can reveal aspects and characteristics of movement that a normal photograph cannot.

How a Conventional Camera Sees Time

With a conventional film or digital camera, objects in motion manifest that motion as a blur. This is because the whole image is exposed over the entire picture plane at once. When the shutter is open, the light reflected off of the moving objects into the camera scatters, exposing numerous images of the same moving object in slightly different locations on the film plane. These multiple images, when combined, become a blurred representation of the object in motion.

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The whole image changes slightly, in each moment of a traditional exposure.

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The composite of these slight changes results in a blur.

How a Scanner Camera Sees Time

A flatbed scanner, on the other hand, doesn't record the entire image off of the picture plane at once. Instead, it reads it line by line. To scan an entire photograph takes between 15 seconds and five minutes, depending on the resolution of the image. Each line of this image, though, is read in a matter of miliseconds.

Here's an example, to make this idea a bit more clear. A 15,000 pixel square (225,000,000 pixels) image takes 90 seconds to scan. Each line of the fi nal image is read one-by-one, in roughly six miliseconds. This happens 15,000 times, with the scan head moving a tiny amount each time. But between the capture of each line, the objects in the scene might move slightly. These changes in position between the 6 milliseond slices of the image, once combined into the whole image, become the motion distortion seen in the scanner photographs.

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Each line of the image is captured by the scanner sequentially, in a tiny amount of time.

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The combination of these lines results in a scanner photograph, with scanner distortion.

This effect is impossible to create to anything near this level of detail or clarity using traditional digital tools. This is because the refresh rate of a video camera is 25 frames per second, and the refresh rate of a digital stills camera is even slower - between one and three seconds per image. Scanner photographs are made up of 15,000 individual slices of time, spread over 15,000 lines. Using any standard video camera to capture images this way can be done, but is limited to 720 lines, and the fastest capture rate is 40 milliseconds. This means that the images will be much low resolution, and the slower capture rate leads to blocky, jagged edges between the frames of video that are used to make up the composite.

Reading the Scanner Photographs

Once the reasons why the motion distortion occurs are understood, they allow scanner photographs to be looked at in a different way - as a sort of 'visual score' recording a sequence of time, rather than as a single instant that has been frozen. By reading the scanner photograph from left to right, like a page of text or a musical score, we can get an understanding of the motion of objects in the scene. For example, if a scanner photograph takes five minutes to scan, we know that the objects recorded on the left side of the image were there five minutes before the objects on the right side of the image. Scanner photographs provide us with a visual timeline, one that, once we know how to read it, gives us a completely different approach to the conventional views of time in a photographic image.

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This photograph took 110 seconds to scan. We can look at any point inside of that photograph, and know when in the scan it was recorded.

Resolution vs. Scan Time

The time taken to scan the image influences both the resolution and the amount of distortion shown. The shorter, lower resolution scans take around 15 seconds, but are smaller (1000 pixels at 15 seconds, vs. 15,000 at 90 seconds or 50,000 at five minutes). The time also influences the distortion level, because smaller images are captured much faster than larger images. We end up referencing the relationship between resolution and scan time as a factor in how we take a photograph. It's similar to the relationship between aperture size and depth of field, where the balances between the two factors must be taken into account in order to get the photograph that we want.

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This 1MB scanner photograph shows little distortion in the moving objects, because of a fast scan time of 15 seconds. It cannot be printed out at a large scale, because the file is too small.

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This (very much scaled down for the web - this page is large enough already!) 140MB scanner photograph shows much more distortion with the same movement, because of the slow scan time of 190 seconds. It can be printed out a a very large scale, because of the high resolution of the file.

Scanner Orientation

The direction of the scan has a huge impact on both the look and the nature of the distortions created by a scanner camera. If the scanner is scanning from left to right, then the 'visual timeline' of the photograph is read from left to right, while if the scanner is scanning from top to bottom, the timeline is read from top to bottom. In theory, this is a very simple idea. In practice, it results in different types of information about movement and time being recorded into the photograph.

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This photograph was scanned from left to right. Because of this, the timeline of the image is horizontal, and the distorted cars are compressed into flattened forms.

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This photograph was scanned from top to bottom. The distortion is much different... people walking past are stretched into thin lines. The angle of the line shows the speed of movement - the more horizontal the line, the faster they were walking. By looking at this photograph, it is possible to track both the speed and number of people walking past the camera.

Sound and Vibration

One very interesting aspect of scanner photography is only visible at very high resolution. Under the right conditions, sound can be seen using the scanner camera. Because sound is carried by the vibration of both air and objects, it is possible to see the effects of very loud sounds on objects in a photographic scene. For example, the rippling of fabric placed close to a speaker can be recorded by a scanner camera, and can provide us with clues as to the rhythm and intensity of the sound that created that movement. This aspect of the scanner camera can also show other intangible forces in a visual manner - for example, wind shaking the camera can be easily read in a scanner photograph.

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This photograph of Jayne County was taken at a concert, and a very loud sound system was present and working during the photograph.

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This detail of the previous photograph shows the rippling in the image caused by the speaker vibrations, and shows us the beat of the song being played.

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This photograph and detail shows the effect of wind, shaking the camera slightly on its tripod.

Color in Scanner Photographs

A common question about the scanner photographs is, 'why are they black and white?'. The answer to this has to do with the way that the scanner captures a color image. In order to record a color image, the scanner breaks the image down into read, green and blue channels by illuminating the scanned artwork with a lamp, capturing each line of each channel separately using a grayscale light sensor, and then combining these three channels into a single color image. A scanner camera, however, doesn't use the lamp to trigger the light sensors, it uses the light projected through the camera body lens. Because of this, the three channels are identical, resulting in a black and white image. The only exception to this is when the camera is photographing a scene changing color even faster than the camera records it. The fast refresh rates of tvs and computer monitors, for example, provide a splash of color in the otherwise grayscale imagery of the scanner camera.

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The flash of color in this image is created by the high refresh rate of the monitor. Because the screen changes color even faster than the scanner records a line of the image, it does not appear black and white.