# US 12,120,284 B2 · Image encryption method using line interlacing and image decryption apparatus therefor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,120,284 B2 - Document ID: US12120284B2 - Status: Granted - Kind: B2 - Application number: 17/710,064 - Filed: 2022-03-31 - Published: 2022-10-06 - Granted: 2024-10-15 - Earliest claimed: 2021-03-31 - Assignees: Korea Advanced Institute of Science and Technology - Applicants: Korea Advanced Institute of Science and Technology - Inventors: Heung Kyu Lee; Sang Keun Ji; Ji Hyeon Kang - Web page: https://patentgrep.com/patent/US12120284B2 ## CPC - H04N 1/4486: {using digital data encryption} - G06T 1/0021: {Image watermarking} - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL ## Abstract An image encryption method. The method includes generating an adjusted secret image by adjusting an intensity range to be the same for each RGB channel of a secret image; generating a modulated image by repeating pixel modulation in block units on the adjusted secret image; and generating an interlaced image by interlacing odd-numbered lines of the adjusted secret image with even-numbered lines of the modulated image or interlacing even-numbered lines of the adjusted secret image with odd-numbered lines with the modulated image. ## Claims ### Claim 1 An image encryption method, comprising: generating an adjusted secret image by adjusting an intensity range to be the same for each RGB channel of a secret image; generating a modulated image by repeating pixel modulation in block units on the adjusted secret image; and generating an interlaced image by interlacing odd-numbered lines of the adjusted secret image with even-numbered lines of the modulated image or interlacing even-numbered lines of the adjusted secret image with odd-numbered lines with the modulated image. ### Claim 2 (depends on 1) The method of claim 1, wherein the generating of the adjusted secret image by adjusting the intensity range adjusts the range of a pixel value to have the same distance of intensity strength from the expectation value of a probabilistic variable representing the pixel value of the secret image. ### Claim 3 (depends on 2) The method of claim 2, wherein the generating of the modulated image comprises: calculating pixel values of a particular block located within a preconfigured range in the adjusted secret image; and performing pixel modulation for each block of the adjusted secret image based on the pixel values of the particular block. ### Claim 4 (depends on 3) The method of claim 3, wherein the performing of pixel modulation for each block of the adjusted secret image performs pixel modulation on each block so that the average value of pixel values of any block located within a preconfigured range falls within a target average range. ### Claim 5 (depends on 1) The method of claim 1, further comprising generating an adjusted public image by adjusting an intensity range to be the same for each RGB channel of the public image, wherein the generating the modulated image generates the modulated image by repeating pixel modulation in block units on the adjusted secret image and the adjusted public image. ### Claim 6 (depends on 5) The method of claim 5, wherein the public image is an image to which an image enhancement scheme has been applied to enhance edge components. ### Claim 7 (depends on 5) The method of claim 5, wherein the generating of the modulated image comprises generating a second modulated image with enhanced image quality by applying an inverse error diffusion scheme to a previously generated, first modulated image. ### Claim 8 (depends on 5) The method of claim 5, wherein, when the intensity range is adjusted, the range of a pixel value is adjusted by considering correlation between intensity strength of the secret image and intensity strength of the public image. ### Claim 9 (depends on 5) The method of claim 5, wherein the generating the modulated image comprises: calculating pixel values of a particular block located within a preconfigured range in the adjusted secret image and the adjusted public image; and performing pixel modulation for each block of the adjusted secret image and the adjusted public image based on the pixel values of the particular block. ### Claim 10 (depends on 9) The method of claim 9, wherein the performing of pixel modulation for each block of the adjusted secret image and the adjusted public image performs pixel modulation on each block so that the average value of pixel values of any block located within a preconfigured range falls within a target average range. ### Claim 11 An image decryption apparatus, comprising: a decryption screen disposed between an encryption object including an interlaced image and a viewing position, wherein the interlaced image is generated by generating an adjusted secret image by adjusting an intensity range to be the same for each RGB channel of a secret image; generating a modulated image by repeating pixel modulation in block units on the adjusted secret image; and interlacing odd-numbered lines of the adjusted secret image with even-numbered lines of the modulated image or interlacing even-numbered lines of the adjusted secret image with odd-numbered lines with the modulated image. ### Claim 12 (depends on 11) The apparatus of claim 11, wherein the decryption screen decrypts the adjusted secret image encrypted by even-numbered lines or odd-numbered lines of the interlaced image. ### Claim 13 (depends on 12) The apparatus of claim 12, wherein the decryption screen comprises a mask that prevents viewing at a position corresponding to an even-numbered line or an odd-numbered line of the interlaced image. ### Claim 14 (depends on 13) The apparatus of claim 13, wherein the mask comprises a polarization filter or a light blocking filter. ### Claim 15 (depends on 11) The apparatus of claim 11, wherein, after further generating an adjusted public image by adjusting an intensity range to be the same for each RGB channel of a public image, the modulated image is generated by repeating pixel modulation in block units on the adjusted secret image and the adjusted public image. ### Claim 16 (depends on 15) The apparatus of claim 15, wherein the decryption screen decrypts the adjusted secret image encrypted by even-numbered lines or odd-numbered lines of the interlaced image. ### Claim 17 (depends on 16) The apparatus of claim 16, wherein the decryption screen comprises a mask that prevents viewing at a position corresponding to an even-numbered line or an odd-numbered line of the interlaced image. ### Claim 18 (depends on 17) The apparatus of claim 17, wherein the mask comprises a polarization filter or a light blocking filter. ### Claim 19 A non-transitory computer-readable storage medium storing a computer program, wherein the computer program, when being executed by a processor, comprises: generating an adjusted secret image by adjusting an intensity range to be the same for each RGB channel of a secret image; generating a modulated image by repeating pixel modulation in block units on the adjusted secret image; and generating an interlaced image by interlacing odd-numbered lines of the adjusted secret image with even-numbered lines of the modulated image or interlacing even-numbered lines of the adjusted secret image with odd-numbered lines with the modulated image. ### Claim 20 (depends on 19) The computer-readable recording medium of claim 19, wherein the image decryption method further comprises generating an adjusted public image by adjusting an intensity range to be the same for each RGB channel of a public image, wherein the generating the modulated image generates the modulated image by repeating pixel modulation in block units on the adjusted secret image and the adjusted public image.