Saliency detection aims to highlight the most relevant objects in an image. Methods using conventional models struggle whenever salient objects are pictured on top of a cluttered background while deep neural nets suffer from excess complexity and slow evaluation speeds. In this paper, we propose a simplified convolutional neural network which combines local and global information through a multi-resolution 4×5 grid structure. Instead of enforcing spacial coherence with a CRF or superpixels as is usually the case, we implemented a loss function inspired by the Mumford-Shah functional which penalizes errors on the boundary. We trained our model on the MSRA-B dataset, and tested it on six different saliency benchmark datasets. Results show that our method is on par with the state-of-the-art while reducing computation time by a factor of 18 to 100 times, enabling near real-time, high performance saliency detection.

A novel real-time homogeneous region segmentation method is proposed that decouples appearance and geometric properties of the regional energy model into data-driven external and regularization driven internal energy functions. The initial seed locations are selected using local minimal variance estimated using minimum rectangle converging criteria. Region convergence is obtained through an iterative co-ordinate descent technique. Since this method requires only 14 ms per video frame, it will help compress intelligent transportation system video for transmission over mobile networks for surveillance and cloud-based processing.

This paper proposes DESIRe (Discontinuous Energy Seam-carving Image Retargeting), an improved seam carving approach for content-aware image retargeting. The proposed algorithm introduces a novel discontinuous seam carving optimization process that incorporates not only a structural energy cost functional, but also a texture energy cost functional to handle scenes with complex structural and textural characteristics. Experimental results using a variety of scenes with dense image detail characteristics show that the proposed DESIRe seam carving approach can provide improved visual quality when compared to a number of existing seam carving methods. These results illustrate the potential of the proposed DESIRe approach for improving content-aware image retargeting that reduces the loss of important image information without causing significant visual distortions or artifacts.

This paper proposes DESIRe (Discontinuous Energy Seam-carving Image Retargeting), an improved seam carving approach for content-aware image retargeting. The proposed algorithm introduces a novel discontinuous seam carving optimization process that incorporates not only a structural energy cost functional, but also a texture energy cost functional to handle scenes with complex structural and textural characteristics. Experimental results using a variety of scenes with dense image detail characteristics show that the proposed DESIRe seam carving approach can provide improved visual quality when compared to a number of existing seam carving methods. These results illustrate the potential of the proposed DESIRe approach for improving content-aware image retargeting that reduces the loss of important image information without causing significant visual distortions or artifacts.

Superpixels have been widely used for compact image representation in a large number of computer vision applications such as object recognition, segmentation, and depth estimation. Recently, a novel seam carving approach for superpixel generation called Grid Seams was introduced that significantly improved image structure preservation while maintaining global spatial constraints. While Grid Seams was able to achieve state-of-the-art superpixel accuracy, it only took advantage of rudimentary edge information in its energy function and as such did not account for other important image characteristics such as texture. Motivated by this, we present Return of Grid Seams (RGS), a novel extension of Grid Seams that takes advantage of not only structural variations, but also textural variations (in the form of texture distinctiveness) into a unified multi-functional energy along with global spatial constraints. Furthermore, RGS incorporates discontinuous seams in the optimization process to allow for greater flexibility in preserving structural information. Experimental results using the Berkeley Segmentation Dataset show that RGS is able to outperform Grid Seams as well as a number of other seam carving based superpixel methods.

Identifying the surfaces of three-dimensional static objects or of two-dimensional objects over time are key to a variety of applications throughout computer vision. Active surface techniques have been widely applied to such tasks, such that a deformable spline surface evolves by the influence of internal and external (typically opposing) energies until the model converges to the desired surface. Present deformable model surface extraction techniques are computationally expensive and are not able to reliably identify surfaces in the presence of noise, high curvature, or clutter. This paper proposes a novel active surface technique, decoupled active surfaces, with the specific objectives of robustness and computational efficiency. Motivated by recent results in two-dimensional object segmentation, the internal and external energies are treated separately, which leads to much faster convergence. A truncated maximum likelihood estimator is applied to generate a surface consistent with the measurements (external energy), and a Bayesian linear least squares estimator is asserted to enforce the prior (internal energy). To maintain tractability for typical three-dimensional problems, the density of vertices is dynamically resampled based on curvature, a novel quasi-random search is used as a substitute for the ML estimator, and sparse conjugate-gradient is used to execute the Bayesian estimator. The performance of the proposed method is presented using two natural and two synthetic image volumes.

Among the main limitations of active contours are their high noise sensitivity and poor capture range from the target object. One of the most promising approaches for addressing these limitations is the concept of Vector Field Convolution (VFC). However, due to its isotropic vector field kernel, VFC does not take full advantage of the underlying image structural characteristics. By specifically addressing this idea, a novel local tensor vector field approach is developed to adaptively account for these structural characteristics. Experimental results demonstrate that the proposed adaptive method leads to more accurate segmentation.

A novel nonlinear volumetric scale-space framework is proposed for multi-scale volumetric data representation. The problem is formulated as a Bayesian least-squares estimator, and a quasi-random density estimation approach is introduced for estimating the posterior distribution between consecutive volumetric scale space realizations. Experimental results using both synthetic and real MR volumetric data demonstrate the effectiveness of the proposed scale-space framework for three-dimensional representation with significantly better structural separation and localization across all scales when compared to existing volumetric scale-space frameworks such as volumetric anisotropic diffusion and volumetric linear Gaussian scale-space, especially under scenarios with high noise levels.

A novel energy functional for automatic registration of remote sensing imagery based on quasi-random scale-space structural correlation is presented. The structural correlation energy functional takes advantage of the fact that, for many types of remote sensing imagery, there exist common structures at different scales even if the acquired images have very different intensity characteristics. The proposed energy functional also takes advantage of the noise robustness and feature localization properties of quasi-random scale-space theory. An efficient globally exhaustive optimization strategy in the frequency domain is developed for registering remote sensing imagery based on the proposed energy functional. Promising test results on interband, intraband, and intermodal remote sensing image sets show that the proposed method has the advantage of being robust to differing sensing conditions and large misalignments.

The accurate detection of object boundaries via active contours is an ongoing research topic in computer vision. Most active contours converge toward some desired contour by minimizing a sum of internal (prior) and external (image measurement) energy terms. Such an approach is elegant, but suffers from a slow convergence rate and frequently misconverges in the presence of noise or complex contours. To address these limitations, a decoupled active contour (DAC) is developed which applies the two energy terms separately. Essentially, the DAC consists of a measurement update step, employing a Hidden Markov Model (HMM) and Viterbi search, and then a separate prior step, which modifies the updated curve based on the relative strengths of the measurement uncertainty and the nonstationary prior. By separating the measurement and prior steps, the algorithm is less likely to misconverge; furthermore, the use of a Viterbi optimizer allows the method to converge far more rapidly than energy-based iterative solvers. The results clearly demonstrate that the proposed approach is robust to noise, can capture regions of very high curvature, and exhibits limited dependence on contour initialization or parameter settings. Compared to five other published methods and across many image sets, the DAC is found to be faster with better or comparable segmentation accuracy.

Object boundary detection has been a topic of keen interest to the signal processing and pattern recognition community. A popular approach for object boundary detection is parametric active contours. Existing parametric active contour approaches often suffer from slower convergence rates, difficulty dealing with complex high curvature boundaries, and are prone to being trapped in local optima in the presence of noise and background clutter. To address these problems, this paper proposes a novel kernel-based active contour (KPAC) approach, which replaces the conventional internal energy term used in existing approaches by incorporating an adaptive kernel derived for the underlying image characteristics. Experimental results demonstrate that the KPAC approach achieves state-of-the-art performance when compared to two other state-of-the-art parametric active contour approaches.

A novel generalized sampling-based probabilistic scale space theory is proposed for image restoration. We explore extending the definition of scale space to better account for both noise and observation models, which is important for producing accurately restored images. A new class of scale-space realizations based on sampling and probability theory is introduced to realize this extended definition in the context of image restoration. Experimental results using 2-D images show that generalized sampling-based probabilistic scale-space theory can be used to produce more accurate restored images when compared with state-of-the-art scale-space formulations, particularly under situations characterized by low signal-to-noise ratios and image degradation.

The extraction of contours using deformable models, such as snakes, is a problem of great interest in computer vision, particular in areas of medical imaging and tracking. Snakes have been widely studied and many methods are available. In most cases, the snake converges towards the optimal contour by minimizing a sum of internal (prior) and external (image measurement) energy terms. This approach is elegant, but frequently mis-converges in the presence of noise or complex contours. To address these limitations, a novel discrete snake is proposed which treats the two energy terms separately. Essentially, the proposed method is a deterministic iterative statistical data fusion approach, in which the visual boundaries of the object are extracted, ignoring any prior, employing a Hidden Markov Model (HMM) and Viterbi search, and then applying importance sampling to the boundary points, on which the shape prior is asserted. The proposed implementation is straightforward and achieves dramatic speed and accuracy improvement compared to other methods.

This paper introduces a novel stochastic approach to image denoising using an adaptive Monte Carlo scheme. Random samples are generated from the image field using a spatially-adaptive importance sampling approach. Samples are then represented using Gaussian probability distributions and a sample rejection scheme is performed based on a chi2statistical hypothesis test. The remaining samples are then aggregated based on Pearson Type VII statistics to create a non-linear estimate of the denoised image. The proposed method exploits global information redundancy to suppress noise in an image. Experimental results show that the proposed method provides superior noise suppression performance both quantitatively and qualitatively when compared to the state-of-the-art image denoising methods.