Latent photo system

Claim 1

A method of producing an invisible latent photograph which is viewable with the aid of a suitable dark screen comprising using a reproduction of the photograph in both negative and positive form, micro halftone photographing both negative and positive forms of said photograph in sequence and in register onto suitable film or paper through a dark screen, having extremely small apertures and angled 30° and 60° in respect to the upper margin thereof, respectively, the resulting latent photograph, having a visual effect of being smooth and continuous is a reflection of the size and shape of the dots, tones, or lines of both positive and negative reproductions, but reduced in size and changed in shape by the small apertures of the dark screen, when thus photographed at two angles 30° apart; the latent photographs obtained reflect only the positive end of the photographic scale, and then only in percentages of from 1/10 of a percent to 5 percent representing the dots, tones or lines of the positive and negative reproductions which varied in percentages of from 1% to 59% being positive in nature and from 60% to 99% being negative in nature; the visible tonal range of the latent photographs are rendered invisible or latent in form by the cancellation effect of the negative and positive micro-halftones photographed through said screen turned 30° from each other during said photographing, to view or see the latent halftones, negative or positive, a dark screen similar to one that produced the latent halftone is placed over the film, or paper containing the latent halftones, and then turned to the appropriate angle, producing a visible halftone of the negative latent image in one case and a visible halftone of the positive latent image in the other; the visible halftones then, are a reflective match of the original reproductions, when in reality the dots, tones, or lines on the original reproduction had both negative and positive aspects, with percentages of from 1% to 99% whereas the combination of the latent halftone and the dark screen reflects only negative aspects, with percentages of from 95% to 99 9/10%.

Claim 2

A method of producing an invisible latent photograph which is viewable with the aid of a suitable dark screen comprising using a reproduction of the photograph in both negative and positive form, micro halftone photographing both negative and positive forms of said photograph in sequence and in register onto suitable film or paper through a dark screen, having extremely small apertures and angled 30° and 60° in respect to the upper margin thereof, respectively, the resulting latent photograph, having a visual effect of being smooth and continuous is a reflection of the size and shape of the dots, tones, or lines of both positive and negative reproductions, but reduced in size and changed in shape by the small apertures of the dark screen, when thus photographed at two angles 30° apart; the latent photographs obtained reflect only the positive end of the photographic scale, and then only in percentages of from 1/10 of a percent to 5 percent representing the dots, tones or lines of the positive and negative reproductions which varied in percentages of from 1% to 59% being positive in nature and from 60% to 99% being negative in nature; the visible tonal range of the latent photographs are rendered invisible or latent in form by the cancellation effect of the negative and positive micro-halftones photographed through said screen turned 30° from each other during said photographing, to view or see the latent halftones, negative or positive, a dark screen similar to one that produced the latent halftone is placed over the film, or paper containing the latent halftones, and then turned to the appropriate angle, producing a visible halftone of the negative latent image in one case and a visible halftone of the positive latent image in the other; the visible halftones then, are a reflective match of the original reproductions, when in reality the dots, tones, or lines on the original reproduction had both negative and positive aspects, with percentages of from 1% to 99% whereas the combination of the latent halftone and the dark screen reflects only negative aspects, with percentages of from 95% to 99 9/10%.

Claim 14

A method of photographically producing a latent image suitable for use in connection with an identification card comprising the steps of preparing positive and negative halftone reproductions of said image in sequence and in register by photographing said positive and negative reproductions of said image through a screen having a plurality of extremely small apertures therein, and separating said halftone images by an angle of 30° relative to each other to render the visible halftones invisible when viewed without the aid of a screen having smaller apertures than said first-mentioned screen placed thereover.

Claim 15

A method of photographically producing a latent image suitable for use in connection with an identification card comprising the steps of preparing positive and negative halftone reproductions of said image in sequence and in register by photographing said positive and negative reproductions of said image through a screen having a plurality of extremely small apertures therein, and separating said halftone images by an angle of 30° relative to each other to render the visible halftones invisible when viewed without the aid of a screen having smaller apertures than said first-mentioned screen placed thereover.

Claim 18

A method of producing on a substrate a latent image of an object which appears to be invisible to the unaided eye, comprising photographing the object through a halftone screen to produce at least one halftone image of the object, placing said halftone image in registry with a strip of light sensitive film and a dark screen having therein a plurality of extremely small apertures arranged in parallel rows oriented in predetermined angular offset relation to the rows of halftone dots forming said halftone image, exposing said strip of film to said halftone image through the small openings in said screen, developing the exposed film to produce thereon the latent image of said object, and imprinting said latent image on said substrate.

Claim 19

A method of producing on a substrate a latent image of an object which appears to be invisible to the unaided eye, comprising photographing the object through a halftone screen to produce at least one halftone image of the object, placing said halftone image in registry with a strip of light sensitive film and a dark screen having therein a plurality of extremely small apertures arranged in parallel rows oriented in predetermined angular offset relation to the rows of halftone dots forming said halftone image, exposing said strip of film to said halftone image through the small openings in said screen, developing the exposed film to produce thereon the latent image of said object, and imprinting said latent image on said substrate.