Improvements in or relating to Photographing in Colours.
Year: 1894

page_text: This Print is in accordance with the Original Specification as it stands after
Amendment (under Section 18 of the Patents, &c., Act, 1883), as allowed
by the decision of the Chief Examiner of the 12th day of March 1897.
Date of Application, 23rd July, 1894-Accepted, 29th Sept., 1894
COMPLETE SPECIFICATION (AMENDED).
Improvements in or relating to Photographing in Colours.
I, JOHN JOLY of 39 Waterloo Road, Dublin, County Dublin, Ireland, Civil
Engineer, 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
following statement :-
The object of my invention is to obtain by means of a single photographic image
of an object, a representation of this object in its natural colours, or in colours
seeming such to the eye.
A sensitive film sensitized for the red rays (when all colours are to be reproduced)
is exposed in the camera beneath a parti-coloured screen consisting of a transparent
colourless plate bearing lines ruled in transparent pigments. These lines may lie
diagonally or otherwise on the plate. They are ruled in three several tints having
such selective light absorption properties as will secure that :-One line will so sift
the light passing through it that the sensitive film beneath will be affected in a manner
corresponding to the manner in which (according to colour measurements such as
Maxwell's) the red sensitive nerves in the human eye are affected by the various
wave lengths of the spectrum: A second line will similarly sift the rays falling upon
it so that the plate beneath will be affected in the same manner as the green sensitive
nerves are affected by the several wave lengths: the third line will do this in the
manner in which the blue-violet sensitive nerves are affected. The coloured lines are
ruled on so as to lie adjacent to one another, and of similar width. A dividing engine
or similar machine being employed to shift the plate beneath the pen or pens on the
completion of each stroke. The dyes or pigments used must be suited to the
sensitiveness of the plate to the several wave lengths. Thus I may use chrysoidine
orange for the red-selecting line, a mixture of ethyl green and chrysoidine orange for
the green selecting line, water blue for the blue-violet selecting line. Or any other
pigment which I may find suitable. The plate taken for exposure under this screen
must be placed in the camera with its sensitive surface bearing in close contact with
the ruled surface of the screen. The rays thus fall upon it after passing through the
screen. An unlimited number of plates may be successively exposed under the
same screen.
Upon development of the plate in the usual manner an image in the usual silver
deposit is obtained which shows no colour but is finely divided into linear areas,
every third area registering the image as sifted through the red-selecting dye,
every third again the image as sifted through the green-selecting dye, every third
again the image as transmitted through the blue-violet selecting dye. It being

page_text: understood that the lines upon the primary or taking screen are in the successive
colour-selective order red, green, blue-violet, red
and so on, no two lines of
the same colour selective properties lying adjacent to one another.
From this negative a positive transparency is printed by contact in the usual manner.
This positive contains the same linear registration of the colour-selective properties of
the dyes only that now what was before opaque has become transparent. If now this
photograph is viewed through a screen with lines ruled in transparent pigments in
correct register with those on the screen used in taking the negative, but in the three
primary colours red, green and blue-violet, and so placed against the photograph that
a red coloured line falls upon a linear strip of the image which had been taken through
a red-selecting line upon the taking screen, a green line upon a strip of the image
previously obtained through a green-selecting line and so for the blue-violet also,
then the image is seen in its original colours. To produce this effect upon the eye
and also not to interfere with the form of the image the lines must be of sufficient
fineness to apparently blend-or be unobtrusive-when viewed by the unaided eye.
Hence it is desirable that the lines be ruled some 200 to the inch or closer.
In viewing the picture through the parti-coloured screen it is essential that the
lines upon both plates, (the photograph and the screen) be in close contact.
I may
use plates of specially flat or polished plate glass to secure closer contact. Instead of
using a separate parti-coloured view screen 1 may rule the primary colours directly
upon the photograph. Similarly instead of using a separate taking screen, I may use
a sensitive plate for taking the photograph in the first instance which has the requisite
selectively-absorbing colour tints ruled directly upon the sensitive surface and
which will wash off in the subsequent operations attending development.
Instead of a linear "pattern" I inay use one consisting of squares, diamonds or
any other similar suitable forms the colours in this case being stamped or rolled
upon the screen plate from a surface bearing minute raised patches suitably spaced so
that after three such printing operations the entire surface of the plate may be
overlaid with patches of the three requisite colours in close juxta-position. The
taking and viewing screens are of course stamped or printed to the same dimensions
and form of "pattern." I may also take and view the photograph through lines
having the same tints, that is tints approximating to the three primary colour
sensations. In cases where I use the same tints for the lines used in taking and
viewing the picture I may lay those down upon the solid transparent support of the
sensitive film as a substratum, and varnishing the ruled lines with waterproof
varnish, deposit the sensitized emulsion upon this substratum. Such a plate is
exposed in the camera through the transparent tinted support and developed as a
positive when without further treatment it reproduces to the eye the colours of the
original object more or less accurately when viewed as a transparency.
I may in
all cases aid the reproduction of the original colours by the use of uniform colour
screens inserted in the path of the rays falling on the plate either for part of the
time of the exposure or during the whole time. Thus I may aid in the registration
of the red rays by inserting a screen cutting off the shorter wave lengths more or
less, for a portion or the whole time of the exposure.
Coloured fluxes nixed with a suitable liquid may be ruled upon the plate in fine
lines or in any regulated fashion to form a screen as before described and then burnt
into the plate. Or by passing the plate under three successive rollers with suitably
spaced raised lines or spaces the three colours may be deposited. In all these
cases I may keep the plate at a raised temperature while putting in the colour so as to
facilitate the drying of the inks and preserving the adjacent lines from running into
each other.
The tints red, green and blue-violet, carried by the view screen are those of the
fundamental colour sensations, approximating to the tint of the red lithium band of
the spectrum for the red, to the green of the E line region of the spectrum for the
green, and to a lapis-lazuli blue for the blue.. These are ruled upon the screen in
such depths as will secure that the finished screen shows little or no colour to the
unaided eye when looked at by transmitted light, but looking darkened or grey due

page_text: to the light absorption of the three tints. I may also depart from these tints some-
what when it may be requisite to do so in order to secure that one and the same
screen shall serve both for taking and viewing the picture the tints in that case being
intermediate of those used on the taking and viewing screens. Or I may use two
tints when pictures of less variety of tints are required.
I find that the aniline dyes mixed with thin dilute gum arabic are suitable for
ruling upon the screen plate,----more especially if this is coated with a thin layer of clear
gelatine which has been allowed to dry before the colours are ruled upon it. I use
ordinary drawing pens with carefully set blades. These are conveniently provided
with micrometer screws for adjusting the width of the lines. But generally it is
requisite by microscopic examination to make sure that each line has the correct
width. It is best to provide separate pens for each colour and have these spaced
relatively to each other by such an amount that the lines ruled by the leading pen
are dry before the lines made by the second pen are deposited near them and so
also for the third set of lines. This spacing may either be at right angles to
the direction of the lines or in the direction of the lines; at the conclusion of each
stroke across the plate, the plate or pens are shifted by the action of the screw of
the dividing engine through the width of three lines in a direction at right angles
to the direction of the lines.
I may mix the dyes with gelatine and rule this upon the screen plate which may or
may not be coated with a preliminary layer of gelatine; the aniline colours or other
colouring matters may be dissolved in warm dilute gelatine and ruled on to the
plate while in a fluid condition. In this case I maintain the pen or pens warm by
the use of a spiral of platinum wire surrounding the upper part of the pen so that
when this is heated by an electric current the requisite temperature is maintained..
Or I may warm the metal frame carrying the pen or pens by the use of gas jets, or
other means. The plate to be ruled may be plain glass or carry a thin film of clear
gelatine as a substratum. The plate may also be warmed, but I find it an
advantage to let the gelatine cool sufficiently upon contact with the plate as to
render it so far set that no running occurs. In this manner I may rule
simultaneously the three colours in adjacent lines only spacing the pens so much.
in the direction of the line as to allow of the setting of the one coloured line before
the next line is deposited alongside of it. Or I may arrange the pens in the
manner already described.
I may use any convenient solvent for the dyes for making the inks and any
convenient substratum upon the plate, or I may dispense with this latter altogether..
I may rule the lines upon celluloid or other transparent support.
The lines may be varied in width when it is desired to give prominence to one
particular tint in the objects photographed. The width of the lines on both:
screens must, however, correspond. Thus if, to strengthen the reproduction of
the red, for example, the red-selecting pigment on the taking screen is ruled some-
what wider than the green and blue selecting pigments, then the lines on the view
screen in the fundamental red colour must be correspondingly wider than those
lines which carry the green and blue tints.
The colours of the view screen may underlie the sensitive film, being primarily
deposited upon the glass support, the colours of the taking screen may be carried on
the outside surface of the sensitive film being deposited in exact register with the view
colours beneath. The plate is exposed through these last colours which wash off upon
development. Or it may only carry the view colours and be exposed through a
removable "taking" screen. In these cases the plate is developed as a positive
when it may be viewed as a photograph in colours owing to the presence of the
visual screen beneath the film.
Or a negative of the image being obtained by exposure beneath a taking screen,
(which may be ruled directly upon the surface of the sensitive film), is printed as a
positive upon a plate carrying a view screen beneath its sensitive layer, the requisite
correct 'register being secured by the use of stops etc.
I may obtain the negative by means of the following arrangement equivalent to

page_text: à finely-divided colour screen. A silvered-glass plate or a plate otherwise coated
with a thin opaque film as by a dark varnish etc., has the opaque film removed in
places according to pattern of fine clear parallel lines spaced at double their own
width from each other. Or the clear spaces are a little less than half the area or
width of the opaque spaces. Such a plate may be formed by a dense photographic
image either by contact printing from such a semi-transparent screen as described
abovo or by a reduced imago of tho required pattern from a larger surfaco or
diagram. The semi-transparent screen is so mounted in the camera, or in the back or
carrier as to be superimposed upon and movable through a known small distance,
across the surface of the sensitive film. Thus the image in the camera only reaches
the sensitive film through the clear lines engraved upon the screen. In taking a
photograph three successive exposures are made and the screen is shifted into three
successive positions, each advance being through the width of one clear space or a
little more and at each advance a differently tinted uniformly coloured screen is
introduced in the path of the rays forming the image. These screens are such as will
secure the proper registration of the several colours upon the plate. Or the opaque
screen may have clear lines so spaced as to admit of two coloured screens being used
successively at successive exposures. The photograph so obtained is viewed through
a screen ruled with the suitable transparent tints in lines registering with those of the
taking screen or I imprint or rule these tints directly upon the positive image. Or
the opaque primary screen may be cleared or perforated according to any regular
pattern engraved or photographed upon it so that the entire surface of the sensitive
plate or nearly so can be exposed by a number of shifts or movements of the screen
corresponding to the number of plain colour tints used in taking the photograph.
Subsequently the photograph so obtained is printed as a positive and viewed through
a screen of transparent tints spaced according to the pattern of the primary screen.
Or the secondary screen may be imprinted or ruled upon the positive.
I may avoid or lessen the effects of parallax, due to the rays of the camera being
divergent and the finely divided screen in some cases not being in optical contact
with the sensitive surface, by placing the colours not in exact juxta-position but so
that a minute distance separates the several coloured lines; the secondary screen
being similarly divided. Thus subsequently when the photograph is looked at
obliquely through the secondary screen there will be less change of tints due to the
parallax arising from the want of optical contact between the screen and the photograph.
Or for direct eye observation of the picture I may regard it through a lens or lenses
so that the rays from the picture to the eye have the same divergence as obtained in
the camera when the picture is being taken.
The image may be formed in the camera upon a parti-coloured screen larger than
the sensitive plate and a lens within the camera used to reduce both image and
screen to the dimensions of the plate. In this way a very fine sub-division of the
image may be secured. Subsequently in viewing or projecting the image a similar
optical arrangement may be used.
Suitable frames can of course be constructed into which the taking and viewing
screens may fit and be at once in register relatively to one another.
It is obvious that any of the above mentioned arrangements may be used in
taking and viewing stereoscopic photographs.
Throughout the Specification 1 have made use of the word "pattern" generally
to denote any regular form whatever in which the colouring matters may be suitably
distributed over the screen in allotted places, the pattern being necessarily regular
although susceptible of variation in form, so long as the colours are not allowed to
dispose themselves promiscuously and in a manner not predetermined.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In taking and viewing a photograph the combined employment of a transparent
sareen for new in taking the whatamanh
"

page_text: having the different selective light-absorption properties described and of a transparent
screen bearing a "pattern" in register with the pattern of the first-mentioned screen,
and in the primary colours described for use in viewing the photographic image taken
through such first-mentioned screen as described.
"
2. Å transparent screen for use in taking and viewing a photograph bearing a
pattern" in colours approximating to the primary colours that is in colours
intermediate of those described for the separate taking and viewing screens and in
such dyes or pigments as have suitable selective light-absorption properties substantially
as described.
"
3. The combination in a sensitive plate for use in photography of a viewing
pattern" in the primary colours a sensitive film and a corresponding taking
pattern" on the surface of the sensitive film in suitable selective light-absorptive
dyes or pigments substantially as described.
66
4. In a camera the combination of a uniform colour screen of suitable selecting
tint an opaque screen bearing a transparent" pattern " and a sensitive plate receiving
the image projected by the lens through the colour screen and through the transparent
pattern of the opaque screen substantially as and for the purpose described.
5. The combination in a sensitive plate for use in photography of a sensitive film
and a layer or stratum of colour dyes or pigments regularly distributed in allotted
order and places suitable for taking and also for viewing in the desired colours a
photographic image.
6. The combination in a photographic camera of a lens a parti-coloured screen such
as described but larger than the sensitive film and upon which the image is projected
by the lens, and of a reducing lens to focus the image formed upon the said screen on
to the sensitive plate substantially as specified.
Dat this 20th day of T.1., 1901
W. P. THOMPSON & BOULT,
Agents for the Applicant.