Optical Color Image Research Articles

Color image cryptosystem using Fresnel diffraction and phase modulation in an expanded fractional Fourier transform domain

In this letter, what we believe is a new technique for optical color image encryption by using Fresnel diffraction and a phase modulation in an extended fractional Fourier transform domain is proposed. Different from the RGB component separation based method, the color image is converted into one component by improved Chirikov mapping. The encryption system is addressed with Fresnel diffraction and phase modulation. A pair of lenses is placed into the fractional Fourier transform system for the modulation of beam propagation. The structure parameters of the optical system and parameters in Chirikov mapping serve as extra keys. Some numerical simulations are given to test the validity of the proposed cryptosystem.

Optical double color image encryption scheme in the Fresnel-based Hartley domain using Arnold transform and chaotic logistic adjusted sine phase masks

The paper presents an opto-double color image cipher using two dimensional (2D) chaotic Arnold transform (AT) as a preprocessing scrambling stage and 2D chaotic Logistic adjusted Sine map (LASM) phase masks in the Fresnel (Fr)-based Hartley Transform (HT). In the proposed opto-double color image cipher, the 2D chaotic LASM is utilized to create chaotic phase masks. The color plainimage red, green and blue channels are firstly scrambled with 2D chaotic AT. Then, the scrambled color plainimage red, green and blue R-G-B channels are modulated using the 2D chaotic LASM phase mask and transformed with the Fr-based HT. The transformed complex R-G-B channels distributions are secondly scrambled with the 2D chaotic AT, modulated secondly with the 2D chaotic LASM phase mask and transformed with Fr-based HT. The utilization of 2D chaotic LASM phase masks in addition to the 2D chaotic AT provides efficient key administration and communication. Also, optical geometric parameters are considered as extra additional keys that enhances the secrecy of the proposed scheme. A comprehensive security study is employed for the proposed scheme and test results verifies and ensures that the proposed scheme is highly immune and resistant against most potential attacks.

Neovascularization detection in diabetic retinopathy from fluorescein angiograms.

Although a lot of work has been done on optical coherence tomography and color images in order to detect and quantify diseases such as diabetic retinopathy, exudates, or neovascularizations, none of them is able to evaluate the diffusion of the neovascularizations in retinas. Our work has been to develop a tool that is able to quantify a neovascularization and the fluorescein leakage during an angiography. The proposed method has been developed following a clinical trial protocol; images are taken by a Spectralis (Heidelberg Engineering). Detections are done using a supervised classification using specific features. Images and their detected neovascularizations are then spatially matched by an image registration. We compute the expansion speed of the liquid that we call diffusion index. This last one specifies the state of the disease, permits indication of the activity of neovascularizations, and allows a follow-up of patients. The method proposed in this paper has been built to be robust, even with laser impacts, to compute a diffusion index.

A hybrid scheme for self-adaptive double color-image encryption

Most of existing optical color image encryption schemes have born security risks due to the adoption of linear transform, and data redundancy for the generation of complex image. To settle these problems effectively, a hybrid scheme for self-adaptive double color-image encryption is proposed in this paper. In this scheme, each RGB color component of two secret color images is first compressed and encrypted by 2-D compressive sensing (CS) in which measurement matrices are generated by 1-D compound chaotic systems and further are optimized by steepest descent algorithm to improve image reconstruction effect. Then, the two measured images are regarded as the real part and imaginary part to constitute a complex image, respectively. In the end, the complex image is reencrypted by self-adaptive random phase encoding and discrete fractional random transform (DFrRT) to obtain the final encrypted data. In the process of DFrRT and random phase encoding, the correlations between R, G, B components are adequately utilized. The production of key streams not only depends on the initial values of chaotic systems but also on plaintexts, and the three color components affect each other to enhance the ability against the known plaintext attack. The projection neural network algorithm is adopted to obtain the decryption images. Simulation results also verify the validity and security of the proposed method.

DWT versus WP Based Optical Color Image Encryption Robust to Composite Attacks

Intensive studies have been done to get robust encryption algorithms. Due to the importance of image information, optical encryption has played a vital role in information security. Many optical encryption schemes have been proposed but most of them suffer from poor robustness. In this paper six proposed algorithms will be presented for optical encryption to be robust to severe attacks: composite attack. Three of these approaches are based on one level Discrete Wavelet Transform (DWT) and the others are based on Wavelet Packet (WP). Not only will new techniques be presented but also a new proposed chaotic map has been developed as random keys for all algorithms. After extensive comparative study with some traditional techniques, it has been found that the novel algorithms have achieved better performance versus conventional ones. Also it has been found that WP based algorithms have achieved better performance than DWT based ones against severe composite attacks.

Optical color image cryptosystem using chaotic baker mapping based-double random phase encoding

This paper introduces an effective optical color image encryption with the use of chaotic baker mapping (CBM) based Double Random Phase Encoding (DRPE). The proposed CBM based-DRPE optical color image cryptosystem first employs a confusion stage by scrambling the input red, green and blue color plainimage components with 2D chaotic baker mapping and applies the first random diffuser. Then the resulted color image components are transformed using Fourier Transform (FT) and scrambled again with 2D chaotic baker mapping. Finally, the resultant complex distributions of color image components are subjected to the second diffuser and fourier transformed again. A set of test experiments are conducted to investigate the encryption quality and security of the proposed CBM based-DRPE optical color image cryptosystem. The achieved results ensured and demonstrated its superiority with respect to encryption quality, histogram, entropy, differential and noise immunity tests.

A Novel Chaotic based Optical Color Image Encryption Technique

A Novel Chaotic based Optical Color Image Encryption Technique

Single-lens Fourier-transform-based optical color image encryption using dual two-dimensional chaotic maps and the Fresnel transform.

We propose an optical color image encryption system based on the single-lens Fourier transform, the Fresnel transform, and the chaotic random phase masks (CRPMs). The proposed encryption system contains only one optical lens, which makes it more efficient and concise to implement. The introduction of the Fresnel transform makes the first phase mask of the proposed system also act as the main secret key when the input image is a non-negative amplitude-only map. The two CRPMs generated by dual two-dimensional chaotic maps can provide more security to the proposed system. In the proposed system, the key management is more convenient and the transmission volume is reduced greatly. In addition, the secret keys can be updated conveniently in each encryption process to invalidate the chosen plaintext attack and the known plaintext attack. Numerical simulation results have demonstrated the feasibility and security of the proposed encryption system.

An optical color image watermarking scheme by using compressive sensing with human visual characteristics in gyrator domain

A novel optical color image watermarking scheme considering human visual characteristics is presented in gyrator transform domain. Initially, an appropriate reference image is constructed of significant blocks chosen from the grayscale host image by evaluating visual characteristics such as visual entropy and edge entropy. Three components of the color watermark image are compressed based on compressive sensing, and the corresponding results are combined to form the grayscale watermark. Then, the frequency coefficients of the watermark image are fused into the frequency data of the gyrator-transformed reference image. The fused result is inversely transformed and partitioned, and eventually the watermarked image is obtained by mapping the resultant blocks into their original positions. The scheme can reconstruct the watermark with high perceptual quality and has the enhanced security due to high sensitivity of the secret keys. Importantly, the scheme can be implemented easily under the framework of double random phase encoding with the 4f optical system. To the best of our knowledge, it is the first report on embedding the color watermark into the grayscale host image which will be out of attacker's expectation. Simulation results are given to verify the feasibility and its superior performance in terms of noise and occlusion robustness.

Optical Color Images Encryption based on Double Random Phase Encoding

Optical Color Images Encryption based on Double Random Phase Encoding

Estimation of the Relative Amount of Hemoglobin in the Cup and Neuroretinal Rim Using Stereoscopic Color Fundus Images

To calculate the relative amount of hemoglobin (Hb) in sectors of the optic nerve head (ONH) from stereoscopic color fundus images using the Laguna ONhE method and compare the results with the visual field evaluation and optical coherence tomography (OCT). Healthy eyes (n = 87) and glaucoma eyes (n = 71) underwent reliable Oculus Spark perimetry and Cirrus OCT. Optical nerve head color images were acquired with a nonmydriatic stereoscopic Wx Kowa fundus camera. Laguna ONhE program was applied to these images to calculate the relative Hb amount in the cup and six sectors of the rim. Receiver operating characteristic (ROC) analysis and correlations between parameters were calculated. We did not observe any variations in the relative amount of Hb in relation to age in healthy subjects (R(2) = 0.033, P > 0.05). Maximum ROC area confidence intervals were observed for a combination between perimetric indices and the Laguna ONhE Glaucoma discriminant function (0.970-0.899) followed by rim area (0.960-0.883), and mean deviation (MD; 0.944-0.857). In glaucoma cases, relative Hb amount presented significant reduction in all rim sectors, especially 231° to 270° and 81° to 120° (P < 0.001), except in the temporal 311° to 40° (P = 0.11). Perimetry mean sensitivity by sectors was better correlated with respective Hb levels than with rim areas or the corresponding nerve fiber thickness, especially the superior and inferior sectors (P < 0.05). Visual field sensitivity was better correlated with Hb levels than with rim sector areas or the corresponding nerve fiber thickness. In many cases the remaining rim show low perfusion, especially in the superior and inferior sectors.

基于频谱融合技术的光学衍射成像彩色图像加密系统

基于频谱融合技术的光学衍射成像彩色图像加密系统

Optical color image hiding scheme by using Gerchberg–Saxton algorithm in fractional Fourier domain

We proposed an optical color image hiding algorithm based on Gerchberg–Saxton retrieval algorithm in fractional Fourier domain. The RGB components of the color image are converted into a scrambled image by using 3D Arnold transform before the hiding operation simultaneously and these changed images are regarded as the amplitude of fractional Fourier spectrum. Subsequently the unknown phase functions in fractional Fourier domain are calculated by the retrieval algorithm, in which the host RBG components are the part of amplitude of the input functions. The 3D Arnold transform is performed with different parameters to enhance the security of the hiding and extracting algorithm. Some numerical simulations are made to test the validity and capability of the proposed color hiding encryption algorithm.

3D Face Recognition Based on Depth and Intensity Gabor Features using Symbolic PCA and AdaBoost

Traditional 2D face recognition based on optical (intensity or color) images faces many challenges, such as illumination, expression, and pose variation. In fact, the human face generates not only 2D texture information but also 3D shape information. In this paper, the objective is to investigate what contributions depth and intensity information make to the solution of face recognition problem when expression and pose variations are taken into account, and a novel system is proposed for combining depth and intensity information in order to improve face recognition performance. In the proposed approach, local features based on Gabor wavelets are extracted from depth and intensity images, which are obtained from 3D data after fine alignment. Then a novel hierarchical selecting scheme embedded in symbolic principal component analysis (Symbolic PCA) and AdaBoost learning is proposed to select the most effective and most robust features and to construct a strong classifier. Experiments are performed on the three datasets, namely,Texas 3D face database, Bhosphorus 3D face database and CASIA 3D face database, which contain face images with complex variations, including expressions, poses and long time lapses between two scans. The experimental results demonstrate the enhanced effectiveness in the performance of the proposed method. Since most of the design processes are performed automatically, the proposed approach leads to a potential prototype design of an automatic face recognition system based on the combination of the depth and intensity information in face images.

Optical color image encryption using position multiplexing technique based on phase truncation operation

Abstract We propose an optical color image cryptosystem based on position multiplexing technique and phase truncation operation. Compared with the reported color image encryption method, we employ the position multiplexing technique to encrypt the color image in only one spatial channel. Meanwhile, our proposed method can maintain the nonlinear characteristic of the cryptosystem and avoid various types of the currently existing attacks, especially the iterative attack. Simulation results are presented to demonstrate the security and robustness performance of the proposed method.

Optical color image encryption based on computer generated hologram and chaotic theory

A novel technique of optical color image encryption and decryption based on computer generated hologram (CGH) and chaotic theory is proposed. The tri-color separated images of an image to be encrypted are encoded with three random phase arrays constructed by a chaotic sequence of the deterministic non-linear system, respectively. Then Burch's encoding method using the modified off-axis reference beam is adopted to fabricate the CGH as the encryption image. A clear original color image can be reconstructed as long as the correct initial value of chaotic sequence and the correct system parameters are given. The initial value of chaotic function with a very small change will lead to the generation of an entirely different chaotic sequences. As a result, the random phase array changes dramatically and the original image cannot be recovered rightly. Serving as the secret keys, the initial values of chaotic sequence and system parameters reduce the amount of the key data. And the digital encryption image is also more favorable to be stored and transmitted. The feasibility and its robustness against occlusion and noise attacks are verified by numerical simulations.

Intraoperative combined color and fluorescent images–based sentinel node mapping in the porcine lung: Comparison of indocyanine green with or without albumin premixing

We developed a multimodal optical imaging system for intraoperative visualization of sentinel lymph nodes (SLNs). This study is to validate our system by showing SLNs in the lung through combined optical color and fluorescent image with indocyanine green (ICG) and ICG with human serum albumin (HSA). Identical ICG concentrations of ICG only or ICG:HSA was injected into the rat footpad and porcine lung. Absolute amounts of the fluorescents were scaled on the basis of animal weights. The entire procedures were recorded using color and near-infrared (NIR) charge-coupled device (CCD) cameras simultaneously, and the 2 images were merged by real-time image processing software. All fluorescence intensity signals to background ratio (SBR) and retention rates at SLN for both fluorescents were estimated and compared. This newly developed intraoperative color and fluorescence optical imaging system successfully visualized the SLNs in animal experiments. The SLNs were identified 100% for both rat and pig under invivo conditions. Real-time image processing software overcame the low signal of NIR fluorescence images. ICG and ICG:HSA provided no significantly different SBR in the SLN images for both rat thigh and pig lung. The intraoperative optical imaging system enabled real-time image-guided surgery during SLN mapping in lung in an animal model. The ICG retention rate was similar to ICG:HSA. ICG alone can be useful for SLN imaging during lung cancer surgery.

Optical color image hiding scheme based on chaotic mapping and Hartley transform

We present a color image encryption algorithm by using chaotic mapping and Hartley transform. The three components of color image are scrambled by Baker mapping. The coordinates composed of the scrambled monochrome components are converted from Cartesian coordinates to spherical coordinates. The data of azimuth angle is normalized and regarded as the key. The data of radii and zenith angle are encoded under the help of optical Hartley transform with scrambled key. An electro-optical encryption structure is designed. The final encrypted image is constituted by two selected color components of output in real number domain.

Optical color-image encryption and synthesis using coherent diffractive imaging in the Fresnel domain

We propose a new method using coherent diffractive imaging for optical color-image encryption and synthesis in the Fresnel domain. An optical multiple-random-phase-mask encryption system is applied, and a strategy based on lateral translations of a phase-only mask is employed during image encryption. For the decryption, an iterative phase retrieval algorithm is applied to extract high-quality decrypted color images from diffraction intensity maps (i.e., ciphertexts). In addition, optical color-image synthesis is also investigated based on coherent diffractive imaging. Numerical results are presented to demonstrate feasibility and effectiveness of the proposed method. Compared with conventional interference methods, coherent diffractive imaging approach may open up a new research perspective or can provide an effective alternative for optical color-image encryption and synthesis.

Optical color image encryption based on the wavelength multiplexing using cascaded phase-only masks in Fresnel transform domain

A novel technique, based on a modified Gerchberg–Saxton algorithm (MGSA) in the Fresnel-transform (FrT) domain, is proposed to encode a color image into three phase-only functions (POFs) for three separated channels: red (R), green (G), and blue (B). The decomposed three RBG channels can avoid the interference of crosstalks efficiently. In proposed decryption process, a color image can be promptly reconstructed by summing of the three decrypted RGB images after the created three POFs which are decrypted one by one. In this paper, all the created three POFs and the system parameters of FrT can be used as the keys for increasing security that are also demonstrated. The computer application simulations to the partial color encryption and decryption are given to validate the feasibility of the proposed scheme.