Image analysis – Applications – 3-d or stereo imaging analysis
Patent
1995-07-19
1998-03-10
Couso, Jose L.
Image analysis
Applications
3-d or stereo imaging analysis
392254, 392299, 348 42, 348 43, 348 44, G06K 900
Patent
active
057270783
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a process for estimating disparity between the monoscopic images making up a stereoscopic image. It applies in particular to the processing of moving stereoscopic images digitized in sequences, this processing making it possible to obtain a description of the relief through measurements of the distances from the movie cameras. It applies for example to the processing of the signal from stereoscopic televisions or to the special effects processing of a stereoscopic image.
DISCUSSION OF BACKGROUND
Stereoscopic image processing, for example making an object stand out from any type of background, other than blue ones in particular, requires a knowledge of the relief of this object.
A stereoscopic image results from the combining of two monoscopic views captured by two cameras placed at different spots, the distance between the cameras being for example equal to the distance between two eyes and their direction simulating the human gaze for example. Each stereoscopic image therefore consists of a pair of monoscopic images. It is known that a knowledge of the point-to-point disparity between the images of one and the same pair makes it possible to deduce the distance of the filmed objects from the cameras and thus to deduce therefrom a relief datum for these objects.
A physical description of the differences between the two images of a stereoscopic pair is obtained through point-to-point matching providing vector data. The disparity field consists of these vector data which are in fact related to the change of perspective between the two images and to the distance from the cameras to the objects of the scene to be filmed.
A method of point-to-point matching of two images, a left image and a right image, making up a stereoscopic image is described in an article: PROCEEDINGS OF THE CONFERENCE ON COMPUTER VISION AND PATTERN RECOGNITION, Miami Beach, 22-26 June 1986, pages 219-226, IEEE, Silver Spring, US; L. R. WILLIAMS et al.: "A coarse-to-fine control strategy for stereo and motion on a mesh-connected commuter".
A hierarchical decomposition of the images is carried out there by levels of resolution, and then an estimate of the disparities between these images is made, starting from the coarsest level of resolution and going towards finer and finer resolutions. This method, using a single pyramid of images of increasing resolutions, does not always afford a sufficiently accurate estimate, especially for slender objects or for outlines, or again when the regions of disparities are substantially uniform.
The point-to-point disparities between the two images of one and the same pair can be described by vectors, called disparity vectors, the purpose of the invention is to obtain a sequence of fields of disparity vectors corresponding to a sequence of stereoscopic images satisfactorily estimating the differences between the two views of a stereoscopic image, especially with a high accuracy.
SUMMARY OF THE INVENTION
To this end, the subject of the invention is a process for estimating disparity between the monoscopic images making up a stereoscopic image, characterized in that it consists: decomposition of each monoscopic image, by levels of resolution, thereby building at least three pyramids of images of increasing resolutions, one low-frequency image pyramid and two high-frequency image pyramids in the horizontal and vertical directions of the images; resolution and in refining the estimate in each level as the resolution increases, the disparity being represented at each point of the image by a vector whose origin is situated at the point of one of the monoscopic images and on the tip at the corresponding point of the other monoscopic image.
The main advantages of the invention are that it improves the accuracy of estimation, especially as regards outlines or slender objects, that it can be used for numerous applications in stereoscopic image processing, and that it makes it possible to associate estimation of motions of ob
REFERENCES:
Glazer, Frank-"Scene Matcing by Hiearchical Correlation", Jan. 1983, pp. 432-441.
Chang et al.-"Multiresolution Stereo by Simulated Annealing" Jun. 1990-pp. 885-890.
"Thomson-CSF"
Couso Jose L.
Do Anh Hong
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