Hiding an image with a light-scattering medium and use of a contrast-discrimination method for readout

Abstract

Hiding image data with a material such as a light-scattering medium is useful as an initial stage of data protection, because the hidden image can be detected only by observation with a specific technique. A light-scattering medium is used to hide the image data, and a low-temporal-coherence interferometer performs the readout processing. A new readout method for detecting pixel values of the image is proposed to overcome spatial variation of the light intensity and distortion of the interference fringes. The introduction of spatial coding further improves the performance by overcoming spatial variations of the light-scattering medium and variations in the reflectance of given pixels.

Avalanche and bit independence characteristics of double random phase encoding in the Fourier and Fresnel domains

“…The double random phase encoding (DRPE) method [3][4][5][6][7], in contrast to the previous techniques mentioned, is an optical encryption technique [8][9][10][11][12][13][14][15][16] that has been used extensively for image encryption, authentication, hiding, and watermarking [17][18][19][20]. The first DRPE technique was originally implemented in the Fourier domain [3].…”

Full-phase photon-counting double-random-phase encryption

“…The role of optical imaging for information security has been investigated by many researchers [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. The double-randomphase encryption (DRPE) technique [1] is able to encrypt and decrypt an image; however, there may be security flaws in the system [2,3].…”

“…Some of these issues may be resolved by frequently updating the phase masks used in the DRPE [3]. Over the years, many improvements to the DRPE have been developed [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. These include using a full-phase processor [4], applying the DRPE in the Fresnel domain [5], or incorporating the DRPE with digital holography [6].…”

Evaluations of phase-only double random phase encoding based on key-space analysis

“…In short, even if the decryption key is slightly different from the encryption key in DRPE, the decrypted image can match the corresponding plaintext image with an allowable level of noise [7]. Owing to this property, DRPE has potential applications in fingerprint verification systems [8][9][10], watermarking [11][12][13], information hiding [14][15][16][17], and multiple-image encryption [18][19][20][21][22][23].…”