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Making Color Images from Prokudi1 (1) .pdf



Nom original: Making Color Images from Prokudi1 (1).pdf
Titre: Making Color Images from Prokudin-Gorskii's Negatives
Auteur: Edition classic

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Making Color Images from Prokudin-Gorskii's Negatives

An Explanation of the Color Rendering Process, “Digichromatography”

There is no known replica or illustration of the
camera that Prokudin-Gorskii used. It was a
view camera of his own design, perhaps
similar to a model [left] designed about 1906
by Dr. Adolf Miethe, whom Prokudin-Gorskii
had met previously in Germany.

Miethe, Adolf, 1862-1927.
Camera and Casette, ca. 1906.
Illustration from Fotograf-Liubitel 17, no. 12
(December 1906): 5.
General Collections, Library of Congress

We know that Prokudin-Gorskii intended his
photographic images to be viewed in color
because he developed an ingenious
photographic technique in order for these
images to be captured in black and white on
glass plate negatives, using red, green and
blue filters. He then presented these images
in color in slide lectures using a lightprojection system [right] involving the same
three filters.

Lantern Projector
Thomas Cradock Hepworth.
Book of the Lantern.
New York: Edward L. Wilson, 1889.

A single, narrow glass plate about 3
inches wide by 9 inches long was
placed vertically into the camera by
Prokudin-Gorskii . He then
photographed the same scene three
times in a fairly rapid sequence
using a red filter, a green filter and a
blue filter.

When viewed through ProkudinGorskii’s camera, the scene being
photographed would have appeared
upside down and reversed from its
actual orientation.
Left: Photograph of Glass Plate
Right: Inverted View Through Camera Lens

For the digital process, the original
tri-part glass negative is scanned
with an overhead digital camera in
grayscale mode. Image-editing
software converts the scan of the
entire plate from negative to positive
form. The scan is inverted to
represent the original physical
orientation.

The entire plate is then reduced to 8bit grayscale mode. Under
magnification, the quality of each
image on the plate is reviewed for
contrast, degree of color separation,
extent of damage to the emulsion,
and any other details that might
affect the final color composite.

The scan of
the entire plate
is aligned and
the outside edges
are cropped.

An electronic file is created for each
image from the cropped tri-part
plate forming three separate
“layers” from which the final color
composite will be generated. The
layers are labeled by color.

While still in grayscale mode,
the red(R), blue(B), and green(G)
layers are aligned forming the
“RGB” color composite.
This registration process is
the most difficult step.

The RGB (Red, Green, Blue)
color composite is cropped
to eliminate all but the photographic
area shared
in common by
all three layers.

The cropped color composite
is adjusted overall to create
the proper contrast,
appropriate highlight
and shadow detail,
and optimal color balance.

Final adjustments may be applied to
specific, localized areas of the
composite color image to minimize
defects associated with over or
underexposure, development, or
aging of the emulsion of ProkudinGorskii’s original glass plate.

The completed color
composite is retouched
to minimize defects
associated with age
and incidental damage.

The glass plate negatives used in this
demonstration:
Prokudin-Gorskii, Sergei Mikhailovich,
1863-1944, photographer.
“The Bukhara Emir”
Prints and Photographs Division
Library of Congress.
Reproduction number: LC-P87-8086A-2

The glass plate negatives used in this
demonstration:
Prokudin-Gorskii, Sergei Mikhailovich,
1863-1944, photographer.
“Pinkhus Karlinskii. Eighty-four years [old].”
Prints and Photographs Division
Library of Congress.
Reproduction number: LC-P87-5006

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