US897815A - Making photographic prints. - Google Patents

Description

No. 897,815. 7 PATENTBD SEPT. 1, 1908. 0. L. A. BRASSEUR. MAKING PHOTOGRAPHIC PRINTS.

APPLICATION FILED JULY 20,1906.

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MAKING PHOTOGRAPHIC PRINTS.

Specification of Letters Patent.

Patented Sept. 1, 1908.

Application filed July 20, 1906. Serial No. 326,976.

To all whom it may concern:

Be it known that I, CHARLES L. A. BRAS- SEUR, a citizen of the United States, and a resident of the city, county, and State of New York, have invented a certain new and useful Improvement in Making Photographic Prmts, of which the following is a specification.

This invention relates to the preparation of plates for use in olychrome rintmg, and has for object the o tention or o tainment of results true or approximately true, in the print, to nature. Theoretically, the trichromatic method of color printin should secure the desired results, but the ifficulty of securing uniformity in the printing has led to the use of-four or more colors to obtain desirable and uniform results. The fourth plate is usuall known 'as thetone plate.

In Letters atent No. 571 ,314, dated November 10, 1896, is set forth a method of forming printing surfaces from a subdivided photograph.

The present invention relates to the formation of a tone plate from a subdivided photograph.

The invention'consists of the method hereinafter described and more particularly pointedout in the appended claims.

The figures of the accom anying drawing, forming part hereof, are iagrams illustrative and explanatory of the invention.

In the draWing-Figure 1 is an enlarged view illustrative of the linear partycolored screen used in taking the subdivided photographs; Fig. 2 is a similar view illustrating a negative of the spectrum taken behind a screen such as is illustrated in Fig. 1; Fig. 3 is a similar view showin a black and white screen laid upon a subdivided photograph and covering two of the partial images thereof; Fig. 4 is a similar view showin a negative of the spectrum, taken fromsuc a positive as is shown in Fig. 3, but with unequal times of exposure for the three partial images; Fig. 5 is a like view showing two partial images (the red and the blue) on one plate; and Fig. 6 shows two juxtaposed partial images on one plate.

In Fig. 1, the reference characters 1' 'g I) mark the lines of the 'artycolored taking screen, while in Fig. 2, t e references 1" g 1; represent negatives (partial images) of the s ectrum taken behind the screen shown in ig. 1, the oints of maximum density of silver deposit being indicated by crowding the lines together and falling in the orange, the yellowish-green, and in the blue regions of the spectrum. In a positive made from such a negative, the points of maximum clearness or whiteness fall the same regions, and the redkpartial image ofsuch a positive isshown in 3 at 1' It will be observed that, in Fig. 2, the densities of deposit are practicall thesame in the red, the green, and t e blue partial ima es, 1' g I), this being re hired in order that white light may be had y synthesis and also that correct color values may be secured on combining the positive with a viewing screen. But it isevident that the same positives, if used only as black and White photographs, will not be orthochromatic in value, as both the green and the blue, in a hotograph of the spectrum have the same lilminosity as the red (reddish-orange). What is true of the spectrum is true to a certain extent of all the negatives obtained by this method. If, therefore, it is desired to obtain from negatives which are correct for color synthesis, ,black and white prints more satisfactory in color-values, or to make a tint plate for color-printing in which the different colors will appear to have about the correct luminosities, it best to proceed as follows, towit: First, make a diapositive by contactrinting from the ori inal negative; then p ace the positive in the copying camera in close contact with a black and white screen ruled as shown in Fig. 3, where the black or o aque lines 0 are twice as wide as any of the ines r g b of 1 that is, the lines 0 cover two of the artial images while leaving the third artia image exposed, as" f this diapositive is copied: 95 m the copying camera, by exposing the shown in Fig. 3.

red image for sa thirty (30) units of time, and then moving the black and white screen so as to ex osethe green image (the red and the us being covered) and without movingh the negative plate on which the red as already been impressed, for, say, twenty (20) units of time; and then agam moving the black and white screen to expose the blue while covering the red and the green, but without moving the negative plate on which the red and the green have now beenseparately impressed, and exposing the blue for, say, ten (10) units of time, then the resulting negative will appear as in Fig. 4, where r g represent t e three partial images, instead of as in sures have been Fig. 2 where the corresponding images are replr'esented by r g 1).

he positive print from the negative shown in Fig. 4 will show the oran e region of the s ectrum quite luminous, t e green less, an the blue least luminouswhich is as it should be in good orthochromatic photography; It is preferred, while making the three exposures .for this second negative (that shown in Fig. 4), to move the negative plate (or, what amounts to the same thing, to move the black and white screen and the positive as one thing) the width of two lines in a direction at right angles to the lines 0, during the exposure of each artial image of the positive, so that each of t e three partial images will be copied upon those portions of the plate which correspond to the other two artial images. This procedure has the effect of a more brilliant negative than is the case where such shifting is not done. It should be understood that the motion of the negative plate (or its described equivalent, the motion of the black and whitescreen and .the positive) is in the plane of the said plate. The purpose of this motion, which, as above stated, is repeated while copying each of the partial images, is to convert't e original negative, made up of three partial images, into one negative made up of three superposed ima es. As a result, there is no appearance of lines, the resulting fringes being absolutely negligible, and if the relative expocorrectly timed, the result obtained is the same as if the negative had been obtained in the first instance through three plain unruled monochrome screens, with the ex osures so timed as to secure correct orthoc omatic'effects. In proceeding in this manner, care must, however, be taken to bring the plate (or screen and positive) back to its (or their) original position, after making one exposure, before beginning the next exposure, or the exposure of another partial image. 1 i

It is to be noted that the essential d-iilerence between the resent method and that described in said etters Patent 571 ,314 is, that in the new method, two or more images (preferably three) of the ori inal negatlve are co ied on one plate, while t 16 old method descri es each of the three partial images constituting the original negative as copled on a different plate, or a separate plate for each partial image. Further, by the new method, the relative luminos ties of the different images are made to differ from that which they had in the original negative.

ying the diapositive, the operator is endifierent parts of the negative corres onding By varying the periods of exposure in co ab ed to vary at will the color values of the to the difierent colors and to obtain t ereby a desired efiect. Moreover, any of the three colorscan be eliminated and the remaining two colors be grouped at will by correspondingly shifting the negative plate and the screen in copying the diapositive. For instance, Fig. 5 shows a negative in which the red and the blue images are each shifted, in the copying, as above described, so that the two images, 1' b, may be said to be placed one on the other, or, rather, each complements the other on the same linear spaces. In Fig. 6 is shown a negative in which the red and blue are placed in juxtaposition. The green partial images are omitted from both Fig. 5 and Fig. 6.

It is evident that any desired or predetermined combination of color values can be obtained by accordingly combining the differ ent negatives and giving suitable ex osures, as, for instance, for making the usua fourth plate, or any sup lementary plates provided with special suita le colorations.

By the term ffourth plate is meant the plate which, in chromo-photographic processes, is printed in a gray or neutral color. Theoretically, this plate is unnecessary, but its use is becoming more and more widespread, as it is undoubtedly helpful as a compensation for the irregularities of tri-chromic printing. As this gray tone must not tarnish or subdue the'bright or light colors, it is essential that the negative from which it is made shall have the color values necessary to attain that end. This result is obtained, in the present method, by giving exposures of different lengths while copying the three partial images. I

The foregoing description applies to colorprinting in the colors of nature, but it is evident that in producing prints which are :merely decorative, any combination of images can be made to obtain desired color effects.

The'fourth plate is made from the photograph described, in any usual or suitable manner, as will be understood.

It will be observed, in Figs. 4 and 5, that each partial image has its own place, and in Fig. 5, that each partial image is rinted over the whole of its own portion 0 the photograph, as indicated by the. references r and b. It will be observed further that, in a positive from a negative such as is shown in Fig. 4 (and from one in which each partial image, covers the whole of its portion of the plate), there is a decrease inluminosity toward the blue end of the spectrum, and an increase in luminosity toward the red end of the spec,- trum. It will also be observed that the de' scribed method enables one to secure a photograph with but one point of maximum density of silver deposit instead of three such points or two such points.

What I claim as new and desire to secure by Letters Patent of the United States is 1. The method, substantially as hereinbefore set forth, of obtaining from a subdivided photograph (negative or diapositive) another photograph (positive or negative), containing a lurality of artial images, in which the co or values or uminosities of the difierent partial images are differently rendered, consisting in printing the selected partial images unequally.

2. The method, substantially as hereinbefore set forth, of obtaining from a subdivided photograph another photograph, containing a lurality of artial'images, in which the co or-values or uminosities of different partial images are rendered in ratios different from that of the original, consisting in printing the selected partial images unequally and each over the whole of its portion of the photograph.

3. The method, substantially as hereinbe-- fore set-forth, of obtaining a fourth'plate for use in polychrome printing consisting. in printing, from a subdivided photograph, another photo raph in which the color values or luminosities of the selected partial images are rendered in a ratio difiering from that of the original, and in making the plate from the second photograph mentioned.

In testimony whereof I have hereunto set my hand in presence of two subscribing Witnesses.

, CHARLESL. A. BRASSEUR.

Witnesses:

A. T. STOUTENBURGH, R. W. BARKLEY.

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