Recent Advances in Optical Image Processing

Alfalou, Ayman; Brosseau, Christian

doi:10.1016/bs.po.2015.02.002

Cited by 63 publications

(17 citation statements)

References 235 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…By the van Cittert-Zernike theorem, the speckle size at the object plane can be calculated with δ (z) = λz/πω and ω is the laser beam waist, which roughly leads to 20 µm. Figure 3(a) shows a typical pattern generated from one row of the Hadamard matrix with order 2 12 , which indicates that the size of the pattern is 64 × 64 pixels. Figure 3(b) shows its corresponding phase-only mask retrieved with the modified Gerchberg-Saxton algorithm.…”

Section: Results and Analysismentioning

confidence: 99%

“…Since Refregier and Javidi proposed the famous image encryption architecture based on double random phase encoding in the Fourier transform domain [11], numerous optical techniques have been widely applied in the field of information security owing to their high speed parallel processing and multidimensional capabilities [12][13][14][15]. Meanwhile, various optical transforms such as fractional Fourier transform, Fresnel transform, gyrator transform, and other means have been applied, where additional parameters can be considered the secret keys to enhance the level of security [16][17][18][19][20][21][22][23][24][25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Optical image encryption via high-quality computational ghost imaging using iterative phase retrieval

Sui

Cheng

et al. 2018

Laser Phys. Lett.

View full text Add to dashboard Cite

A novel computational ghost imaging scheme based on specially designed phase-only masks, which can be efficiently applied to encrypt an original image into a series of measured intensities, is proposed in this paper. First, a Hadamard matrix with a certain order is generated, where the number of elements in each row is equal to the size of the original image to be encrypted. Each row of the matrix is rearranged into the corresponding 2D pattern. Then, each pattern is encoded into the phase-only masks by making use of an iterative phase retrieval algorithm. These specially designed masks can be wholly or partially used in the process of computational ghost imaging to reconstruct the original information with high quality. When a significantly small number of phase-only masks are used to record the measured intensities in a single-pixel bucket detector, the information can be authenticated without clear visualization by calculating the nonlinear correlation map between the original image and its reconstruction. The results illustrate the feasibility and effectiveness of the proposed computational ghost imaging mechanism, which will provide an effective alternative for enriching the related research on the computational ghost imaging technique.

show abstract

Section: Results and Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Optical image encryption via high-quality computational ghost imaging using iterative phase retrieval

Sui

Cheng

et al. 2018

Laser Phys. Lett.

View full text Add to dashboard Cite

show abstract

“…Optical image encryption [1]- [16] has made significant advances in recent decades. The interference-based encryption (IBE) scheme [17] proposed by Zhang and Wang is useful for optical image encryption because of its simple structure and an encryption process that does not involve iteration.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric Optical Image Encryption With Silhouette Removal Using Interference and Equal Modulus Decomposition

Luan

Chen

et al. 2020

IEEE Photonics J.

View full text Add to dashboard Cite

We propose an asymmetric optical image encryption scheme with silhouette removal by using interference and equal modulus decomposition (EMD). Plaintext is first separated into two complex value masks with the same modulus using EMD in the Fresnel transform domain. The two masks are encoded into four phase-only masks (POMs), two of which are treated as ciphertexts and other two as plaintext-dependent private keys by using the inverse Fresnel transform with different diffraction distances and interference-based encryption. Any information about the plaintext, including its silhouette, cannot be retrieved using one, two, or even three of the four POMs. Our scheme also avoids the constraint of the same modulus in EMD and eliminates the vulnerability against the iterative amplitude-phase attack and advanced iterative amplitude-phase attack. Numerical simulations were used to verify the validity and security of our proposed method.

show abstract

“…While acoustic methods offer the undoubted advantage to cover larger volumes of water at low resolution, optical systems are needed for habitat mapping and monitoring, as their richer data accommodates more accessible analyses, for instance in terms of species identification, enumeration, and distributions. High-definition camera sensors, improved artificial illumination systems, LIDAR sensors for bathymetry, range-gated imaging systems, and holography are all aspects in which underwater vision technology has greatly advanced in the recent years to improve coastal and open ocean habitat mapping [4][5][6][7][8][9]. Light source is often considered a critical element in these applications, and imaging systems are distinguished as passive when they rely on natural lighting, or active when artificial illumination is used.…”

mentioning

confidence: 99%

Range-Gated Imaging System for Underwater Monitoring in Ocean Environment

et al. 2018

View full text Add to dashboard Cite

High-quality video observations are very much needed in underwater environments for the monitoring of several ecosystem indicators and to support the sustainable development and management of almost all activities in the ocean. Reliable video observations are however challenging to collect, because of the generally poor visibility conditions and the difficulties to deploy cost-effective sensors and platforms in the marine environment. Visibility in water is regulated by natural light availability at different depths, and by the presence of suspended particles, scattering incident light in all directions. Those elements are also largely variable in time and space, making it difficult to identify technological solutions that can be used in all conditions. By combining state-of-the-art "time of flight" (ToF) image sensors and innovative pulsed laser illumination, we have developed a range-gated camera system (UTOFIA) that enables affordable and enhanced 3D underwater imaging at high resolution. This range-gated solution allows users to eliminate close-range backscattering, improving quality of the images and providing information on the distance of each illuminated object, hence giving access to real-time 3D measurements. Furthermore, as the system is based on pulsed laser light, it is almost independent of natural light conditions and can achieve similar performances at an extended depth range. We use this system to collect observations in different oceanographic conditions and for different applications, including aquaculture monitoring, seafloor mapping, litter identifications and structure inspection. Performances are evaluated by comparing images to regular cameras and by using standard targets to assess accuracy and precision of distance measurements. We suggest that this type of technology can become a standard in underwater 3D imaging to support the future development of the ocean economy.Sustainability 2019, 11, 162 2 of 13 create a turbid environment that strongly increases light scattering and enhances the absorption probability of photons [3]. When the light source is the sun, this process effectively decreases the amount of ambient light present at any depth and limits the range of visual observations. With artificial illumination, the range for underwater vision can be extended (for example we can move deeper) but at the cost of degrading image contrast due to (forward-and back-) scattering generated by suspended particles. The situation is similar to driving a car in foggy conditions with the headlights on: increasing the power of illumination does not improve the visibility, as the backscattering increases proportionally. Image contrast is also lowered with shorter visual range as the light attenuation will reduce the illumination of distant targets. These factors remain the outstanding challenges in underwater imaging and limit the application of visual observations in many sectors [1,2,4].Various optical and acoustic imaging systems for mitigating or solving these problems are under constant develo...

show abstract

Recent Advances in Optical Image Processing

Cited by 63 publications

References 235 publications

Optical image encryption via high-quality computational ghost imaging using iterative phase retrieval

Optical image encryption via high-quality computational ghost imaging using iterative phase retrieval

Asymmetric Optical Image Encryption With Silhouette Removal Using Interference and Equal Modulus Decomposition

Range-Gated Imaging System for Underwater Monitoring in Ocean Environment

Contact Info

Product

Resources

About