Dr. Vikas Ramachandra Profile

Dr. Vikas Ramachandra

at Qualcomm Inc

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Author

Publications (15)

Proceedings Article | 7 March 2014 Paper

Structured light 3D depth map enhancement and gesture recognition using image content adaptive filtering

Vikas Ramachandra, James Nash, Kalin Atanassov, Sergio Goma

Proceedings Volume 9020, 902005 (2014) https://doi.org/10.1117/12.2058772

KEYWORDS: Image enhancement, Image filtering, 3D image enhancement, Gesture recognition, Digital filtering, 3D image processing, Cameras, Reflectivity, Imaging systems, Structured light

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Proceedings Article | 12 March 2013 Paper

Introducing the cut-out star target to evaluate the resolution performance of 3D structured-light systems

Tom Osborne, Vikas Ramachandra, Kalin Atanassov, Sergio Goma

Proceedings Volume 8650, 86500P (2013) https://doi.org/10.1117/12.2008560

KEYWORDS: Stars, Cameras, Imaging systems, 3D acquisition, 3D image processing, Rubidium, Target detection, Projection systems, 3D metrology, Structured light

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Structured light depth map systems are a type of 3D system where a structured light pattern is projected into the object space and an adjacent receiving camera is used to capture the image of the scene. By using the distance between the camera and the projector together with the structured pattern you can estimate the depth of objects in the scene from the camera. It is important to be able to compare two systems to see how one compares to another. Accuracy, resolution, and speed are three aspects of a structured light system that are often used for performance evaluation. It would be ideal if we could use the accuracy and resolution measurements to answer questions such as how close two cubes can be together and be resolved as two objects. Or, determine how close a person must be to the structured light system in order to determine how many fingers this person is holding up. It turns out, from our experiments, a systems ability to resolve the shape of an object is dependent on a number of factors such as the shape of an object, its orientation and how close it is to other adjacent objects. This makes the task of comparing the resolution of two systems difficult. Our goal is to choose a target or a set of targets from which we make measurements that will enable us to quantify, on the average, the comparative resolution performance of one system to another without having to make multiple measurements on scenes with a large set of object shapes, orientations and proximities to each other. In this document we will go over a number of targets we evaluated and will focus on the “Cut-out Star Target” that we selected as being the best choice. Using this target we will show our evaluation results of two systems. The metrics we used for the evaluation were developed during this work. These metrics will not directly answers the question of how close two objects can be to each other and still be resolve, but it will indicate which system will perform better over a large set of objects, orientations and proximities to other objects.

Proceedings Article | 12 March 2013 Paper

Self-calibration of depth sensing systems based on structured-light 3D

Vikas Ramachandra, James Nash, Kalin Atanassov, Sergio Goma

Proceedings Volume 8650, 86500V (2013) https://doi.org/10.1117/12.2008556

KEYWORDS: Calibration, Cameras, Image processing, Projection systems, Image filtering, Sensing systems, Imaging systems, Factor analysis, Image compression, Fourier transforms

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Proceedings Article | 7 March 2013 Paper

Temporal image stacking for noise reduction and dynamic range improvement

Kalin Atanassov, James Nash, Sergio Goma, Vikas Ramachandra, Hasib Siddiqui

Proceedings Volume 8667, 86671P (2013) https://doi.org/10.1117/12.2008559

KEYWORDS: Denoising, Sensors, Image stacking, High dynamic range imaging, Image registration, Imaging systems, Image restoration, Quantization, Cameras, Anisotropic diffusion

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Proceedings Article | 7 March 2013 Paper

Touch HDR: photograph enhancement by user controlled wide dynamic range adaptation

Steve Verrall, Hasib Siddiqui, Kalin Atanassov, Sergio Goma, Vikas Ramachandra

Proceedings Volume 8667, 86671O (2013) https://doi.org/10.1117/12.2008557

KEYWORDS: High dynamic range imaging, Photography, Image enhancement, Tablets, Cameras, Digital cameras, Cell phones, Digital photography, Sensors, Image processing

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Proceedings Article | 19 February 2013 Paper

Digital ruler: real-time object tracking and dimension measurement using stereo cameras

James Nash, Kalin Atanassov, Sergio Goma, Vikas Ramachandra, Hasib Siddiqui

Proceedings Volume 8656, 865606 (2013) https://doi.org/10.1117/12.2008562

KEYWORDS: Electronic filtering, Sensors, Cameras, Optical filters, Filtering (signal processing), Nonlinear filtering, Stereoscopic cameras, Calibration, Error analysis, 3D metrology

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Proceedings Article | 24 February 2012 Paper

Unassisted 3D camera calibration

Kalin Atanassov, Vikas Ramachandra, James Nash, Sergio Goma

Proceedings Volume 8288, 828808 (2012) https://doi.org/10.1117/12.909616

KEYWORDS: Calibration, Cameras, 3D image processing, Sensors, Video, Image processing, Stereoscopic cameras, Detection and tracking algorithms, 3D displays, Image quality

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Proceedings Article | 18 February 2012 Paper

3D discomfort from vertical and torsional disparities in natural images

Christopher Tyler, Lora Likova, Kalin Atanassov, Vikas Ramachandra, Sergio Goma

Proceedings Volume 8291, 82910Q (2012) https://doi.org/10.1117/12.915466

KEYWORDS: 3D displays, 3D image processing, 3D modeling, Cameras, Visualization, Data modeling, 3D vision, Stereoscopic cameras, Eye models, Eye

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Proceedings Article | 2 February 2011 Paper

Multithreaded real-time 3D image processing software architecture and implementation

Vikas Ramachandra, Kalin Atanassov, Milivoje Aleksic, Sergio Goma

Proceedings Volume 7871, 78710A (2011) https://doi.org/10.1117/12.872594

KEYWORDS: 3D image processing, 3D displays, Image processing, Video acceleration, Video, Zoom lenses, Cameras, Video processing, OpenGL, Eye

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Proceedings Article | 27 January 2011 Paper

3D image processing architecture for camera phones

Kalin Atanassov, Vikas Ramachandra, Sergio Goma, Milivoje Aleksic

Proceedings Volume 7864, 786414 (2011) https://doi.org/10.1117/12.872617

KEYWORDS: 3D image processing, Cameras, 3D displays, Sensors, 3D modeling, Calibration, Zoom lenses, Stereoscopic cameras, Image processing, Logic

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Proceedings Article | 27 January 2011 Paper

Introducing the depth transfer curve for 3D capture system characterization

Sergio Goma, Kalin Atanassov, Vikas Ramachandra

Proceedings Volume 7864, 78640E (2011) https://doi.org/10.1117/12.879193

KEYWORDS: Cameras, Stereoscopic cameras, 3D image processing, Image processing, Brain, Eye, Visualization, Stereoscopy, Neuroimaging, 3D metrology

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Proceedings Article | 27 January 2011 Paper

Content-based depth estimation in focused plenoptic camera

Kalin Atanassov, Sergio Goma, Vikas Ramachandra, Todor Georgiev

Proceedings Volume 7864, 78640G (2011) https://doi.org/10.1117/12.872667

KEYWORDS: Cameras, Spatial resolution, Image resolution, Reliability, Digital filtering, Resolution enhancement technologies, Diffusion, Data centers, Digital cameras, Photography

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Proceedings Article | 24 January 2011 Paper

RAW camera DPCM compression performance analysis

Katherine Bouman, Vikas Ramachandra, Kalin Atanassov, Mickey Aleksic, Sergio Goma

Proceedings Volume 7867, 78670N (2011) https://doi.org/10.1117/12.872637

KEYWORDS: Modulation transfer functions, Image compression, Image processing, Cameras, Quantization, Stars, Data compression, Eye, Data storage, Image quality standards

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Proceedings Article | 25 February 2010 Paper

Is a no-reference necessary and sufficient metric for video frame and stereo view interpolation possible?

Vikas Ramachandra, Truong Nguyen

Proceedings Volume 7524, 752413 (2010) https://doi.org/10.1117/12.839942

KEYWORDS: Video, Visualization, Motion estimation, Cameras, Error analysis, Databases, Multimedia, Analytical research, 3D displays, Stereoscopic displays

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Proceedings Article | 19 January 2009 Paper

Depth-based 2D-3D combined scene images for 3D multiview displays

Vikas Ramachandra, Matthias Zwicker, Truong Nguyen

Proceedings Volume 7257, 72570I (2009) https://doi.org/10.1117/12.805449

KEYWORDS: 3D displays, 3D image processing, Visualization, Spatial resolution, Cameras, Gaussian filters, 3D visualizations, Video, 3D vision, 3D applications

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Showing 5 of 15 publications

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