Abstract:
An encryption method for an image, alphanumeric message, random pattern, or any other visual depiction is disclosed. Furthermore, a device for decoding the concealed message created in accordance with the aforementioned method is disclosed. The method and device rely on the limited range of light wavelengths which trigger phosphorescence in a given material. Those wavelengths can be combined with others to obscure the activating light pattern when viewed by the human eye.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    U.S. Provisional Patent Application Number 62/051,284, filed on Sep. 16, 2014. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0003]    The present invention is a novel method for creating hidden images. It is in the broad technical field of cryptography. More specifically, it conveys a technique for embedding visual information in digital images in a manner such that this information is not visually obvious. The present invention further describes a tool which is able to convert this information to a visible form, thereby decoding it. 
         [0004]    Techniques for creating, sending, and revealing secret messages have wide-ranging applications. Many novelty items, such as board games and activity books, incorporate devices which allow for secret messages to be exchanged. “Invisible ink” pens and red-reveal lenses are central to game-play in many amusement products. Similar techniques and devices may also be applied in the field of anti-forgery and document authentication. In both high-security and low-security applications, widespread knowledge of the encryption technique compromises its effectiveness. The present invention presents an as-yet unknown technique, and thus responds to the continuous need for novel encryption techniques. 
         [0005]    Unlike other methods which utilize phosphorescence to communicate messages (Published Applications WO 1998042518 A1, US 20060093777 A1), the present invention relies on the selective response of phosphorescent materials to signals of specific wavelength ranges. Although such a coupling has been previously described using specialized equipment for product authentication (U.S. Pat. No. 7,846,639), until now, this phenomenon could be used in conjunction with everyday consumer products to transmit messages. Here, a skilled method is described for integrating signals of specific wavelengths in visible images, such that the visible image conceals the signal. This provides the advantage of enabling users to encoding and decoding complex signals. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    The present invention describes a method for obscuring a message (or series of messages) which a user desires to conceal in a digital flat panel display screen, and also describes a tool which allows the user to reveal this message (or messages) on an analog substrate. The message is thereby transferred off of the screen onto a different tangible surface, and this secondary surface does not require connection to a power source. 
         [0007]    This method is based on the selective luminescence of phosphorescent pigments, which emit light when excited by a limited portion of the visible light spectrum. This novel method relies on this selectivity, which allows for a multi-color image on a digital device to be transformed by a secondary object coated with phosphorescent pigment. The coated object reveals a hidden message concealed within the image on the screen. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a top view of a device with a digital screen bearing an instance of this invention; 
           [0009]      FIG. 2  is a perspective view of an alternative device with a digital screen bearing an instance of this invention; 
           [0010]      FIG. 3  is a top view of one possible instance of the decoding tool of this invention; 
           [0011]      FIG. 4  is a side view of the decoding tool of  FIG. 3 ; 
           [0012]      FIG. 5  is a perspective view of the decoding tool of  FIG. 3 ; 
           [0013]      FIG. 6  is a top view of another possible instance of the decoding tool of this invention; 
           [0014]      FIG. 7  is a sequential illustration of the decoding tool of  FIG. 3  as it decodes a message; 
           [0015]      FIG. 8  is a sequential illustration of the decoding tool of  FIG. 3  as it decodes a message; 
           [0016]      FIG. 9  is a schematic of the decoding tool of  FIG. 3  being used to decode a message on the device with a digital screen of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    Referring now to the invention in more detail, in  FIG. 1  there is shown a device  10  with a digital flat panel display screen  12  displaying an image  50 . In  FIG. 2  there is shown an alternative device  20  with a digital flat panel display screen  22  also displaying an image  50 . The device  10 ,  20  may be a smart phone, laptop computer, tablet computer, television set, or any other electronic device with a flat panel display. The flat panel display  12 ,  22  may be a liquid crystal display, cathode ray tube, plasma display panel, light-emitting diode, or any other electronic visual display which emits multi-colored light. 
         [0018]    In further detail, still referring to  FIG. 1  and  FIG. 2 , the image  50  may show a pattern, picture, written message, random texture, or any other visual depiction composed of more than one color. In its preferred embodiment, the image  50  has additionally been programmed such that it contains an encrypted image. The encrypted image is a visual depiction of a pattern, picture, written message or any other image. The encrypted image and the primary image coexist in the same image plane, with the primary image being significantly more obvious to the human eye when viewing image  50  on the flat display screen  10 ,  20 . 
         [0019]    The construction details of the encrypted message as shown in  FIG. 1  and  FIG. 2  are that the image  50  is composed of thousands of pixels, each pixel having three sub-pixels with red, green, and blue color filters respectively. The intensity of light being emitted from each subpixel may be set to approximately 256 different levels by the voltage applied to individual electrodes. Thus the subpixels in each pixel combine to emit one of approximately 16 million unique colors (i.e. 256×256×256). 
         [0020]    Referring now to  FIG. 3-FIG .  5 , there is shown a planar object  100  with a coating  104  applied to a substrate  102 . The object  100  represents the decoding tool of the present invention. Referring now to  FIG. 6 , the coating  104  is shown to be applied to a piece of fabric, representing another embodiment of the decoding tool  200 . The object  100 ,  200  may be a greeting card, a post-card, a shirt, a bag, a tissue cloth, a coaster, a box, or any other object with at least one planar surface. 
         [0021]    In further detail, still referring to  FIG. 3-FIG .  6 , the coating  104  is made from a material containing phosphorescent pigments with sufficient quantum yield to be considered “glow in the dark” pigments. Examples of inorganic minerals which are used in phosphorescent paints are as follows, but are not limited to: zinc sulfate, strontium aluminate, and alkaline earth metal silicate. Powders derived from these minerals may be ground up and mixed with a polymer binder and solvent vehicle to create a paint-like substance so that the coating  104  may be adhered to the substrate  102  of the object  100 ,  200 . 
         [0022]    In still further detail, referring to the coating  104  shown in  FIG. 3-FIG .  6 , the coating  104  emits photons following exposure to photons of a certain wavelength. The emitted light is of always of a longer wavelength than the exciting light. In the preferred embodiment of this invention, the coating  104  is excited by photons in the range of 200-450 nm (ultraviolet-blue) and emits in the range of 500-550 nm (green). The emitted light is visible in the absence of intense light sources, for a time period dictated by the process of electrons returning to ground state. 
         [0023]    Referring now to  FIG. 7  and  FIG. 8  of the invention, the decoding tool  100  is shown in its pre-activated state  110 , then in its activated state  112  and finally in its post-activated state  114 . The pre-activated state  110  has not recently been exposed to photons in the exciting range, thus emits no light. The activated state  112  has recently been exposed to photons in the exciting range, in areas  120 ,  122  which represents glowing regions on the coating  104 . 
         [0024]    In further detail referring to  FIG. 7  only, the activation source was in the form of the letters “ABCD”  120 . Referring now to  FIG. 8  only, the activation source was in the form of a star. Following the return of electrons to ground state, the coating is in the post-activated state  114  which is identical both in appearance and function to the pre-activated state  110 . The image  120 ,  122  is thus shown to be a temporary mark. 
         [0025]    In further detail referring to  FIG. 7  and  FIG. 8 , the activation source may be of varying forms  120 ,  122 . In both cases the mark  120 , 122  is shown to be temporary and can be followed by another mark of any shape. In both cases the coating  104  returns to a blank state  114  once the electrons have returned to ground state. 
         [0026]    Referring now to  FIG. 9  the decoding tool  100  is shown being used in conjunction with an image  50  on screen  12  of electronic device  10 . It is intended that this is carried out in a dark room, in the absence of competing intense light sources. The decoding tool  100  must be pressed so that the coating  104  is in contact with the screen  12 , and preferably is held in contact in this position for at least five seconds. Afterwards, the decoding tool  100  is separated from the screen  12  and flipped so that the user is able to see the coating  104 . The encrypted message  120  appears as a glowing image on the coating on decoding tool  100 . 
         [0027]    In further detail, still referring to  FIG. 9  of the present invention, as well as  FIG. 1  and  FIG. 2 , the image  50  is programmed to contain an encrypted message  120 . The encrypted message  120  is achieved by means of controlling the subpixel of each pixel which delivers light of the wavelength closest to the range which will activate the phosphorescent coating on the decoding tool  100 . In the instance where the activating range is 200-450 nm, blue is the only subpixel out of red, green and blue which will trigger phosphorescence. Thus, by essentially isolating all of the blue subpixels, and not reacting to the red or the green subpixels, the decoding tool  100  is able to present the encrypted message  120  to the end user. 
         [0028]    In broad embodiment, the present invention is a system for creating encrypted messages in multi-colored pixels on electronic flat display screens which can be decoded by means of a phosphorescent decoding tool. 
         [0029]    While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention.