Improvements in the Method of and Means for Producing Images in Complementary Colors, suitable also for Use in Taking, Projecting, Inspecting, Testing, or Combining Three Color Photographs, Prints, or the like.
Year: 1899

page_text: Date of Application, 1st July, 1899
Complete Specification Left, 26th Apr., 1900-Accepted, 1st Aug., 1900
PROVISIONAL SPECIFICATION.
Improvements in the Method of and Means for Producing Images in
Complementary Colors, suitable also for Use in Taking, Projecting,
Inspecting, Testing, or Combining Three Color Photographs,
Prints, or the like.
I, GUSTAV SELLE, Physician, of Brandenburg, in the Empire of Germany, do
hereby declare the nature of this invention to be as follows:-
Ever since 1865 when Ducos du Hauron first gave some practicable methods
for reproducing the colors of nature by means of a primary color photography,
it has been known that if in conjunction with 3 color filters, light was trans-
mitted through 3 monochrone transparencies representing the three primary color
sensations, three colored images would arise which when superimposed would
yield an image in the three colors of the original. With a view of facilitating
such projection and superposition, apparatus more or less identical was devised
by Zink, Ives, Nadar and others. The commercial value of such methods is
however small. In the methods above referred to the three transparencies are
projected in the colors of the light filters, ie the monochrome image representing
the blue sensation is transmitted blue; the monochrome image representing
the red sensation is transmitted red, and the monochrome image representing the
green sensation is transmitted green. But when three colour sensations have to
be reproduced on paper or other opaque substance either by pigment photography
or by pigment printing, the pigments used must not be of the same tint as the
light filters or a false picture would result, but the tints must be spectroscopically
complementary to the filters i.e. the red sensation image must be printed in
green; the green sensation image in red, and the blue sensation image in yellow.
I effect the reconstitution of a non-pigmentary colored image by reflection-pro-
jection instead of by transmission-projection and thereby obtain an image niade
up of the complementary tints. I achieve this by making from three negatives,
obtained in the well known manner, three positive black prints on a white opaque
If light be now
surface preferably for instance photographic silver paper.
allowed to fall on such prints and then by suitable means be reflected back
through the corresponding light filters on to a common point the result will be a
combination of three complementary color images. If in such an apparatus I
substitute sheets of white paper for two of such prints the third print will be
seen coloured to a tint complementary to that of the filter through which it is
seen. In this manner a printer can readily ascertain not only the tint but the
depth of pigment to be employed in printing the particular image and he can
also judge of the length of time for printing the negatives in the production of
the printing blocks, matters of great importance because a three color print being
5 in substance nothing else but an effect of various reflections of color rays an
excellent result can only be obtained if the tint and depth of the layers of
pigment on the paper correspond with the gradations of the negatives."
reflection-projection may be carried out by means of suitably arranged mirrors
The

page_text: but with a view of facilitating this to non-experts, I have constructed an
apparatus which apart from arrangement in detail is based on well known
prínciples. It is obvious that any other similar construction may be used so
long as it meets the intended object.
A chamber or box is constructed having in one wall three orifices and in
another wall an eye hole or eye piece. Within the chamber are certain reflecting
mirrors namely four opaque mirrors and two transparent mirrors. The backs of
the latter are colored, that of the one green, that of the other blue, the green
and blue coatings being also transparent. This apparatus views simultaneously
three prints placed in the same plane. One of these prints is reflected from an
opaque mirror to a transparent mirror and thence to the view point. Another
print is reflected from another opaque mirror to the other transparent mirror
thence through the first transparent mirror to the view point. The last print is
reflected from the third opaque mirror to the fourth opaque mirror and thence
through the two transparent mirrors to the view point.
The opaque mirrors may be quicksilver mirrors. Whilst the course of the
rays entering the apparatus follow well known laws the reflecting devices are so
arranged as to yield an image combining the greatest luminosity with correct
superposition. The two transparent mirrors standing at nearly a right angle
to each other are parallel each to one of the quicksilver mirrors, all four being
fixed on one base; the third quicksilver mirror is placed as near as possible to
the corresponding opening in the case so as to receive a bright and distinct an
impression as possible and the fourth quicksilver mirror is so placed that the rays
reflected therefrom shall pass in a direct line through the two transparent
mirrors. The angles at which the rays are reflected from the prints being
identical they can be adjusted to coincide in superposition when arriving at the
common viewing point. The 3 openings may contain the 3 light filters but a
red light filter is sufficient when the aforesaid colored transparent mirrors are
used since in that case the latter act by themselves as light filters. The three
monochrome black prints, having been mounted on a suitable support in a similar
order to the position of the three openings or windows of the chamber, are placed
at a sufficient distance at the back of the apparatus to allow day or artificial
light to fall upon them. The prints thus reflected one over the other will give
at the view point a colored image composed of three reflections in complemen-
tary tints. To explain the complementary reflection more particularly I will
describe the procedure to be observed when it is intended to project the prints
singly or in partial combination so as to serve as a guide and proof to the
printer. Assuming that the image to be reproduced is a black circle on a white
ground, the positive prints will be three black circles on a white ground. Having
placed these prints at the back of the apparatus as already described we would
first constitute the yellow image since that is the color with which printers
usually begin, i.e. the first print to be reflected would be the one representing the
blue sensation. If the other two prints are covered up with black the uncovered
print alone will be reflected and will appear at the view point as a black circle
on a blue ground. If now a white surface, a sheet of paper for instance, be
substituted for the black at one of the former prints so that for example the
light of the green filter will be projected onto the former image it will efface the
black circle and give instead at the view point a green circle on a blue and
green ground if now a white paper be substituted for the black at the last
covered print, the red filter light will be projected on to the double projection
already formed so that the circle will appear red + green (yellowish) on a red +
green blue (i.c. white) ground, thus yielding the yellowish image complemen-
fary to the blue sensation print. If again we reflect the print before the green
filter covering up the others with white paper we shall get a red + blue (ie.
purple red) circle on a red + blue + green (white) ground .e. the pinkish image
complementary to the green sensation if lastly we reflect the third print,
covering up the others with white we get a green +blue light bluish circle

page_text: red
on a + green blue (white) ground. It will be seen from the above that if
the three prints are reflected simultaneously the result is, minus, red green and
blue, black circle on a plus, red green and blue white ground or a reflection
by subtraction on a reflection by addition.
--
Apart from its value to printers, the method is of great advantage to the
amateur since in conjunction with the easily made silver prints the reflection as
described offers a ready means of producing the constituent negatives for a
colored picture. If a lens be fixed at the view point and a slide containing the
sensitive plate be placed at the back of the apparatus the latter can be used
as a camera. The three photographs are then taken either simultaneously or
consecutively. In the former case the difference in actinism between the three
groups of rays have to be provided for by retarding screens or other suitable
equalizing devices, in the second case the exposures are effected successively by
making the reflections operative one at a time only. This is accomplished by
substituting two removable opaque mirrors for the transparent mirrors and with-
drawing the first after the red exposure and the second after the blue exposure.
Further the successive exposures may be made by means of a special slide, namely
a frame having 3 openings corresponding with the openings at the back of the
apparatus. The openings in the slide are provided with shutters. The plate
having been inserted in a slide one would proceed by drawing the shutters at the
three openings consecutively. It is obvious that instead of taking the three
images on a single plate, separate plates may be used for each aperture which
is the preferable course when it is intended to produce subsequently a photograph
or print in pigments or when plates of different color sensitiveness are used.
The slide may also have six apertures and shutters instead of 3 so that by
turning the slide upside down it might be used for another series of exposures
and this again may be duplicated on the back of the slide forming a double
slide suitable for four series of exposures.
1
1000
HERBERT HADDAN & Co.,
Agents to Applicant, 18, Buckingham Street, Strand, London.
COMPLETE SPECIFICATION.
Improvements in the Method of and Means for Producing Images in
Complementary Colors, suitable also for Use in Taking, Projecting,
Inspecting, Testing, or Combining Three Colour Photographs,
Prints, or the like.
I, GUSTAV SELLE, Physician, of Brandenburg, in the Empire of Germany, do
hereby declare the nature of this invention and in what manner the same is to
be performed to be particularly described and ascertained in and by the follow-
ing statement:-
1
Ever since 1865 when Ducos du Hauron first gave some practicable methods
for reproducing the colors of nature by means of a primary color photography, it
has been known that if in conjunction with three color filters, light was trans-
mitted through three monochrome transparencies representing the three primary
color sensations, three colored images would arise which when superimposed
would yield an image in the three colors of the original. With a view of facilitat-
or less identical was
ing such projection and superposition, apparatus more
devised by Zink, Ives, Nadar and others. The commercial value of such methods
is however small. In the methods above referred to the three transparencies

page_text: .
are projected in the colors of the light filters, i.e. the monochrome image represent-
ing the blue sensation is transmitted blue, the monochrome image representing
the red sensation is transmitted red, and the monochrome image representing
the green sensation is transmitted green. But when three color sensations have
to be reproduced on paper or other opaque substance either by pigment photo-
graphy or by pigment printing, the pigments used must not be of the same tint
as the light filters or a false picture would result, but the tints must be spectro-
scopically complementary to the filters i.c. the red sensation image must be
printed in green; the green sensation image in red, and the blue sensation image
in yellow. I effect the reconstitution of a non-pigmentary colored image by
reflection-projection instead of by transmission-projection and thereby obtain an
image made up of the complementary tints. I achieve this by making from
three negatives, obtained in the well known manner, three positive black prints
on a white opaque surface preferably for instance photographic silver paper. If
light be now allowed to fall on such prints and then by suitabile means be
reflected back through the corresponding light filters on to a common point the
result will be a combination of three complementary color images. If in such
an apparatus I substitute sheets of white paper for two of such prints the third
print will be seen colored to a tint complementary to that of the filter through
which it is seen. In this manner a printer can readily ascertain not only the
tint but the depth of pigment to be employed in printing the particular image
and he can also judge of the length of time for printing the negatives in the
production of the printing blocks, matters of great importance because a three
color print being in substance nothing else but an effect of various reflections
of color rays an excellent result can only be obtained if the tint and depth of the
layers of pigment on the paper correspond with the gradations of the negatives.
The reflection projection may be carried out by means of suitably arranged
mirrors but with a view of facilitating this to non-experts, I have constructed an
apparatus which apart from arrangement in detail is based on well known
principles. It is obvious that any other similar construction may be used so
long as it meets the intended object.
The apparatus is shown in the annexed drawing in which Fig. 1 is a vertical
section on line 1-1 of Fig. 2, and Fig. 2 a horizontal section on line 2-2 of
Fig. 1. Figs. 3 and 4 are diagrammatic plan views of dark slides for use with
the apparatus when used as a camera.
A chamber or box 1 is constructed having in one wall three orifices a b c and
in another wall an eye hole f or an eye piece. Within the chamber are certain
reflecting mirrors namely four opaque mirrors 2, 7, 8, 9 and two transparent
mirrors, 3, 6. The backs 4, 5 of the latter are colored, that of the one 4 green
and that of the other 5 blue, the green and blue coatings being also transparent.
This apparatus views simultaneusly three prints placed in the same plane A-B.
One of these prints &e is reflected from an opaque mirror 7 to a transparent
mirror 6 and thence to the view point o. Another print d³ ³ is reflected from
another opaque mirror 2 to the other transparent mirror 3 thence through the
first transparent mirror 6 to the view point 0. The last print is reflected from
the third opaque mirror 8 to the fourth opaque mirror 9 and thence through the
two transparent mirrors 3 6 to the view point o. The opaque mirrors may be
quicksilver mirrors.
Whilst the course of the rays entering the apparatus follow well known laws
the reflecting devices are so arranged as to yield an image combining the
greatest luminosity with correct superposition. The two transparent mirrors 36
standing at nearly a right angle to each other are parallel each to one of the
quicksilver mirrors 2, 7, all four being fixed on one base; the third quicksilver
mirror 8 is placed as near as possible to the corresponding opening in the case so
as to receive as bright and distinct an impression as possible and the fourth
quicksilver mirror 9 is so placed that the rays reflected therefrom shall pass in a
direct line through the two transparent mirrors 3, 6. The angles at which the

page_text: rays are reflected from the prints being identical and the respective distances
being equal they can be adjusted to coincide in superposition when arriving at
the common viewing point O. The three openings a b c may contain the three
light filters but a red light filter at c is sufficient when the aforesaid colored
transparent mirrors are used since in that case the latter act by themselves as
light filters. The three monochrome black prints having been mounted on a
suitable support in a similar order to the position of the three openings or windows
of the chamber, are placed at a sufficient distance at the back of the apparatus to
allow day or artificial light to fall upon them. The prints thus reflected one
over the other will give at the view point O a colored image composed of three
reflections in complementary tints. To explain the complementary reflection
more particularly I will describe the procedure to be observed when it is intended
to project the prints singly or in partial combination so as to serve as a guide and
proof to the printer. Assuming that the image to be reproduced is a black
circle on a white ground, the positive prints will be three black circles on a
white ground. Having placed these prints at the back of the apparatus as
already described we would first constitute the yellow image since that is the
color with which printers usually begin i.e. the first print to be reflected would
be the one de representing the blue sensation. If the other two prints are
covered up with black the uncovered print alone will be reflected and will appear
at the view point as a black circle on a blue ground. If now a white surface,
a sheet of paper for instance be substituted for the black at one say de¹ of the
former prints so that for example the light of the green filter will be projecting
onto the former image it will efface the black circle and give instead at the view
point a green circle on a blue + green ground; if now a white paper be sub-
stituted for the black at the last covered print e³, the red filter light will be
projected on to the double projection already formed so that the circle will appear
red green (yellowish) on a red + green + blue (i.e. white) ground, thus yield-
ing the yellowish image complementary to the blue sensation print. If again
we reflect the print de before the green filter covering up the others with
white paper we shall get a red + blue (i.e. that is purple red) circle on a red -+-
blue green (white) ground i.e. the pinkish image complementary to the green
sensation; if lastly we reflect the third print covering up the others with
white we get a green + blue light bluish circle on a red + green + blue (white)
ground. It will be seen from the above that if the three prints are reflected
simultaneously the result is, minus, red green and blue,= black circle, on a plus
red green and blue = white ground, or a reflection by subtraction on a reflection
by addition.
=
Apart from its value to printers, the method is of great advantage to the
amateur since in conjunction with the easily made silver prints the reflection as
described offers a ready means of producing the constituent negatives for a
colored picture. If a lens be fixed at the view point and a slide containing
the sensitive plate be placed at the back of the apparatus the latter can be
used as a camera. The three photographs are then taken either simultaneously
or consecutively. In the former case the difference in actinism between the
three groups of rays have to be provided for by retarding screens or other
suitable equalizing devices, in the second case the exposures are effected succes-
sively by making the reflections operative one at a time only. This is accom-
plished by substituting two removable opaque mirrors for the transparent
mirrors 6, 3 and withdrawing the first after the red exposure and the second
after the blue exposure. Further the successive exposures may be made by
means of a special slide as shown in diagram in Figs. 3 and 4, namely a frame
having three openings a b c corresponding with the openings a
back of the apparatus. The openings in the slide are provided with shutters
5 as in Fig. 4. The plate having been inserted in the slide one would proceed
by drawing the shutters at the three openings consecutively. It is obvious that
instead of taking the three images on a single plate, separate plates may be
c at the

page_text: used for each aperture which is the preferable course when it is intended to
produce subsequently a photograph or print in pigments or when plates of
different color sensitiveness are used. The slide may also have as shown in
Fig. 4 six apertures and shutters instead of three so that by turning the slide
upside down it might be used for another series of exposures and this again may
be duplicated on the back of the slide forming a double slide suitable for four
series of exposures.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I declare that what I claim is:-
1. In three color photography constituting a non-pigmentary colored image by
the simultaneous reflection projection to one common point of 3 monochrome
prints through corresponding primary color filters.
2. The translation into complementary color images of black monochrome
images representing the 3 primary color sensations by means of black prints on
a white opaque substance projected by reflection through respective color screens.
3. Constituting a single complementary non pigmentary image by reflection.
projection to a common point of a black print on a white opaque ground and
two even white surfaces substantially as described.
4. Constituting a primary black monochrome print into its complementary
equivalent by reflecting it to a given point through its color filter and super-
posing thereon the tints of the other two filters either by reflection projection
or transmission projection.
5. The apparatus containing reflecting devices arranged substantially as and
for the purpose herein described.
6. The combination of reflecting devices and black prints in the manner and
for the purpose substantially as described.
7. A dark slide with apertures and shutters substantially as and for the
purpose described.
8. In reflecting apparatus used as a camera, the method of effecting successive
exposures in the manner substantially as herein described.
ated this 25th day of April 1900.
HERBERT HADDAN & Co.,
Agents to Applicant, 18, Buckingham Street, Strand, W.C., London.