v Patented lJuly 1 l, 193.9

This invention relates to photo-mechanical to l. my? invention, Ainl'imakirig f a color; printer?r from processes for the reproduction of a multi-colored@ this negativa ...,1. 1. 1;;1. "ff/"'7 original. It relates to the makingl of color .Í.Fig. ¿1d illustrates a corrected color--sep'arationï printer for use in such a process andßmoref'p'ar# positive y`¢;>'1‘•‘printérresulting from my'process..y 'f „ p* ticularly to a color printer which is correctedior­ »Y . Fig. '2.i11ustra'tes 'a' novel picture ' which can'> be -5 the limitations of the best contemporarily avail-_ ' made. according to. one‘embodiment ïof my ‘inven-f: able inks. > . It is an object of vthe invention Ato aA tion.'My invention. is ` primarily-' >~concerned -. ‘ ­ vlvvithï'the method of making a color-correctedcolor printer.. makin‘glrof acorrectedicolor printer Vfromfa pri-L.y Various methods of color correction generally mary. . color v'separation ` negative ‘which "has `¿been­ .10 rca1led"‘masking methods” are wellknownii"Itisv made in’anyfof the usual Ways. f Afpo‘s‘itive‘ madey an object of the present invention‘to providea from-i. a fcolorf separatiomnegative ­may­ comprise' method of color correction which" might : ybe the .printers itself> or Vvthe " printer v‘may b'e“ made termed "autographic” and whichdoesnot require“ therefrom7 by any‘f‘suitable duplicating " process.> 15 the use of special masks but employs the original OneVH Well-knov‘vn ‘method I of introducing».` color 15 itself, or more exactly a color separationimagefof correction infth’eï making ‘of fa' color ‘printer com# the original, to act as a mask.y ‘ > f »Y prises` masking ‘certain'of'ïthe color 1Vseparation. The method provided by my` ¿invention ist one, negatives ‘ with .low Lcontrast v‘positives ’ madey from in which neither the negative nor z the color other color separationfnegativesf» Anotherfmethlá.. .¿, 20 printer madev therefrom is maskedl in >the .usual od-l-nam'e'ly 'that for l'which the «above-mentioned.: `20 sense, but a corrected printer» is'madefby. idi'rect. Hahn apparatus `was .intendedLintroduc'es uthek exposure through an ordinary;color’iseparation. colon correctionlduring thefmaking of theînegaë tive,I by exposing the sensitive negative material l negative.It is a special object ofy my`v. invention, , ,f . topro-` to acolor separation“ image 'from-the original; 'i ' vide a photo-mechanical -processins’whichthe: ñrst through a negative mask corresponding‘to‘ 1 density of the blacks and~.îdark grays, ize. .areas ai correcting'ïcolorie.' g: a. redfñlter negative may where all three color printersfhave >a relatively befusedftofcorrect afgreerr ñlter negative)`= and high printing density, are reducedlmoreor less­ second, directly. " ` . ` i i 1: »i :According toümy- invention,.ïa •‘method >.off‘inf i» proportionally)., It is a further object­ of my lnventionïtoïproi troducing color vcorrection is provided which does vide a novel picture ora multi-colored'original not employ either a negativemask (in making the: in which all the neutralfdensity tones are lreduced negative) or a positive mask (in makingy .the­ to a constant value andi‘whic'zhicomprises>` only printer)­ in theusualy sense»r of the fword«mask. color variations. Instead, I `employthe-.original .itself ` as: the mask It is 'also an object of.l the'iinventiontoï pro­` v in ,fither` following.¿mannen`>l` Afcolor- separation -35 I vide a'method of making-‘.suchfa novelipicture; . f negative yis madeiirom >the `originaluand a Yposi--x` Although my invention may- be practiced with tive is made from ¿this :negative :by exposingèra various types yof equipment; .one'fformi'ofß appa-1 photographic‘layer> twice .through the negative, ` - ratus 4which `is particularly «suitable for practice first-'sto ' uniformfillumination r(preferably"gvvhite ing oneembodimenïòf my -invention- is described light).":and second», tofa color. separationqimagè. '40 by F. Hahn in UISJPatent 1,576,118.41v lof the original., -çThislnst .colonia-“a2 correcting: AOther objects and'a’dvar'ita‘ges` of my *invention color;A e. g. in making` amagentagp‘rinter .through will be apparentisfromî the ïfollowingïvdescription afgreen-¿separation negative,>the_,.second exposure; when read in Lfcónnection `v'vithithe. accompanying may;y .be made fbyfa “red >separation image,V thatiàis 45 by illuminating .theënegativeîawith aqredsepara. drawing' Fig. 1a inshowsalwel which: f ., „known manner.V.;. v of making:. tion; image “of `fthe .. original. a' This :image may. fbe` a halftone.­, color «".separationf-:negative' from .a a projected image of.theìßoriginalsorfit -mayçbev Vmulti-colored originali? .constitutes .theffiirsti provided l._by; placing; >the .original in fcontact »ewith step of . my q process;y lone. lemlgaodiment „iofff which 3. is. 1iäht.f„.»;'.1‘11e.iwothe negative and;yilluminatinggiti; exposures maybemade With;,_~,c.olored »s 5o 50 shown `in „the -form » of »a ",flow.. cha ‘ v v 2 2,165,407 tives are made. 'I'he complementary colors, i. e., without disturbing this relation. However, vari the colors of the printers are called blue-green, ' ous ‘arrangements may be used. For example, in magenta, and yellow respectively. In certain making the steps shown .in‘Flg. 1b, the negative branches of press-printing work these comple I5' is illuminated by a color separation image of mentary colors are called blue, red and yellow. the original, which image may be a projected one but this latter convention and its accompanying as shown or'it may be the original itself. The confusion will be avoided in this speciñcation. negative I5' may be placed in contact and reg The term "photographic” is used in a broad sense ister with the original II, which is then illu so that “photographic layer” includes those used minated from in front or behind. If illuminated as photo-sensitive resists as well as the usual from in front (i. e. so that the light is reilected 10 silver-halide emulsions. ' . to the lens I3) the density and contrast of the I will now describe the particular embodiment negative I5’ is eüectively doubled since the light of my invention which is illustrated in the ac must transverse it twice. A transparency is the companying drawing. more suitable form of original to be illuminated ' 15 -As shown in Fig. 1a, a multi-colored original from behind. In fact, if the original is a trans 15 II, which may be either a transparency or an parency, all three elements-the original, the opaque painting or color photograph, is photo negative and the sensitive layer I1 may be super graphed by a process camera represented by a imposed in relative contact and illuminated by lens I3, in the image plane of which is placed a colored light. ' ' 20 film or plate I5. In this particular embodiment As shown in Flg.‘1a, I prefer to expose the of the invention a halftone negative is produced negative I 5 through the base. By doing this, the by positioning a halftone screen It at a suitable negative image I5' can be simultaneously placed distance in front of the sensitive layer of the in contact with the sensitive photographic` layer ñlm or plate I5. A primary color filter I2 (red, Il and in register with a. color separation image green, or blue) is mounted in front of the lens of the original as shown in Fig. 1b. If the original 25 I3 in any well-known manner. Any other suit is a transparency, the negative I5 may be ex able method of making a color separation nega posed directly and then both the original and tive may be employed. the negative turned over in making the step After development, this ñlm or plate i5 com shown as Fig. `117. On the other hand, if the 30 prises a color separation negative I5'. As shown original is not a transparency and it is not de 30 in Figs. 1b and 1c, a positive I'I is made from this sirable to make the exposure of the negative I5 color separation negative I5’ by contact print through the base as shown in Fig. la, a reflector ing. In Fig. 1b, the negative I5' is illuminated such as a prism may be placed in front of the by a color separation image of the original, by lens in performing the step shown as Fig. 1b. means of a set-up similar to that shown in Fig. This reflector introduces the lateral inversion 35, la, but employing a color filter I6 which trans necessary to permit the negative image I5’ to be mits a color which is suitable for`correcting the simultaneously in contact with the sensitive sur color printer corresponding to the color separa face of Il and in register with a color separation tion negative I5'. For example, it has been image of the original. found desirable to correct a magenta printer in My invention is applicable to either continuous 40 proportion to the amount of red present in the tone or halftone processes. In a halftone proc original. In making a magenta printer, a green ess, I prefer to introduce the halftone pattern by iilter is used at I2 to make a green separation making each color separation negative through negative i5'. The exposure of ‘the positive i'I il a halftone screen, as shown, but the halftone lustrated in Fig. lb is then made through a red pattern may be introduced at a later stage such 45 ñlter I6. as when the positive' Il is being exposed. If the In addition to this correcting color exposure, original is a transparency and no enlargement or .. the positive Il receives a direct exposure» modu reduction is required, it is possible to perform my lated by the negative I5’ only. This may be ac invention without the use of any camera, by complished in a simple manner as shown in,Fig. using contact halftone screens and making all 50 1c by placing a sheet of white material I8 in front exposures by contact as discussed above. That of the original II and giving a White “ñash” ex is, the color separation negative is made by con posure. tact printing and the positive is made therefrom After receiving the two exposures as shown in also by contact printing. ’ Figs. 1b and 1c, the photographic layer I'I is de Since according to the arrangement shown in 55 veloped in any suitable and well-known manner the drawing, the image on I1 is laterally inverted to form a corrected color separation positive or with respect to the original, this positive may printer I'I’ as shown in Fig. 1d. comprise the printer itself and a correctly As pointed out above, the steps shown as Figs. oriented `print will result therefrom. In photo 1b and 1c may be performed in either order or gravure work, the corrected positive I1 can, of 60 simultaneously. One simple method of making course, be used directly. However, if desired a these two exposures simultaneously is to use a negative may be made directly from the corrected -» color filter at IG which is diiîusing (i. e. trans positive I'I and any suitable type of printer made lucent rather than transparent) over a predeter therefrom in a well-known manner. mined portion of its area. This portion may be Furthermore, according to my invention, I am 65 adjustable, for example, an adjustable sector of ' able to provide a novel picture of a multi-colored ground glass may partially replace or be super original, in which all visual density gradations imposed on the color ñlter. (i. e. all blacks, grays, and Whites) are reduced The step shown in Fig. 1c may be made in any to the same average gray tone, but in which the 70 well-known manner, by contact printing, as color variations are reproduced substantially cor 70 shown, or by projection printing.I In making this rectly. Since all three color photography is based exposure, the illumination on the negative is uni on the sensitivity characteristics of the human form, preferably white. Since the sensitive layer eye, this novel picture is perhaps more accurately I‘I and the negative I5' are arranged in printing defined as one having only color variations and 75 relation it is desirable to perform both exposures substantially uniform ~visual density. 'I‘his is 75 2,165,407 3 shown in Fig. _2. In the more general case, the separation positive image of the original, said last relative visual densities may be controlled within mentioned color being a correcting color and dif limits to any desired value. In a special case, ferent from that corresponding to the negative. the neutral densities-_i. e. whites, grays and 2. In a photo-mechanical process for the re blacks are reduced to an average gray, but the production of a multi-colored original, the density variations of certain colors are not so re method of making a corrected color printer which

, duced. ' comprises making a color separationnegative and One useful application of a novel picture having ' making a positive therefrom by exposing a sensi only color variationsis as a test chart for the tive photographic layer in printing relation to 10 investigation of color'blindness. As is known, the negative illuminated by uniform illumination 10 color blindness test charts comprises areas which and by a color separation positive image of the have practically identical visual densities­ but original, said last mentioned color being a cor which differ slightly in hue. Indeed, it may bev recting color and different from that correspond desirable in some cases to introduce a slight ing to the negative. , i 15 known difference in visual density as well as the 3. In a photo-mechanical process'for the re 15 difference in hue. ' production of a >multi-colored original, the According to a special embodiment of my in method of making a corrected color printer which vention, a novel color picture of the above'type comprises making a color separation negative 'having uniform visual density, is made up from and making a positive therefrom by positioning a three color printers each of which is made in the sensitive photographic layer in printing relation 20 following manner. A color separation negative is with the negative, illuminating the negative with made by any suitable system such as that shown uniformly distributed illumination and with il in Fig. 1a. A printer or positive is made there lumination comprising a color separaten positive from by any suitable system equivalent to that image of the original, the/amounts of said illu shown in Fig. 1b, wherein the color of the filter­ minations being in predetermined relation and I6 is practically complementary to that of the said last mentioned color being a correcting color primary color filter l2. No “flash” or exposure and ldifferent from that corresponding to the corresponding to that shown in Fig. 1c is given negative, and developing the layer. in this case. I have`found that useful results 4. In a photo-mechanical process for the re are obtained when the' color of the ñlter I6 is production of a multi-_colored original, the any spectral range not transmitted by the pri method of making a corrected color printer which mary color filter i2. ` comprises making a color separation negative of By choosing certain color filters and/or giving the original and making a positive therefrom by a small ñash exposure such as indicated in Fig. positioning a sensitive photographic layer in 1c a certain predetermined amount of density printing relation with the negative and illuminat 35 variation of the colors and/or the neutral tones, ing the negative with light whose distribution may be included as well as the color variation. over the negative is made up of predetermined Obviously, this permits many various types of relative amounts of a uniform portion and the color blindness test charts to be made. ` portion corresponding to a color separation posi Furthermore, this effect-_namely the reduction tive image of the original, the last mentioned of blacks to a\_gray­­­provides another important color being a correcting color an digerent from advantage to the ñrst described embodiment of that corresponding to the separation negative. my invention. Those skilled in this art are aware 5. In a photo-mechanical process for the re that a reduction o_f the density of blacks and dark >production of a multi-colored original, the 45 grays is ­desirable in many cases, and> this reduc- _ method of making a corrected color printer tion is inherently provided by a’. process which em which comprises making a color separation nega ploys my invention to obtain color correction. tive, placing a sensitive photographic layer sub At the same time, by choosing a suitable total stantially in contact with said negative, and ex exposure the highlights or white areas of the posing the layer through >the negative to a uni original are made to appear as zero printing form beam of light and to a color separation posi density on each of the printers, in the usual way. tive image yof the original, said last mentioned Having thus described one embodiment of my color being a correcting color and different from invention in detail andseveral ways in which it that corresponding to the negative. may be employed, I wish to point ‘out'that it is 6. In a’ photo-mechanical process for. the re-v 55 not limited to' the speciiic arrangements shown production of a multi-colored original,` the but is of _the scope of the appended claims. method of making a corrected color printer which What I claim and wish to protect by Letters , comprises making a_ color separation negative by Patent of the United States is: exposing a sensitive photographic layer through 1. In a'photo-mechanical process for the re its support, placing another sensitive photo production of a multi-colored original, the vgraphic layer substantially in contact with said method of making a corrected color printer which negative, and exposing the last-mentioned layer comprises making a color separation negative .through the negative to a uniform beam- of light and making a positive therefrom by exposing a and to a color separation positive image ofthe sensitive photographic layer to two separate ex original, said last mentioned color being a cor 65 posures, one in printing relation to the negative recting color and different from that correspond uniformly illuminated and the other in printing ing to the negative. _ __ Y " relation to the Anegative illuminated by a color ALEXANDER MURRAY.