Ultrasonic imaging apparatus with adaptable spatial image combination
An ultrasonic imaging apparatus using a method for combining CMB images of the same object including a step of seeking representative contours CNT of an interface on the images to be combined IM,[I], IM[J] is disclosed. The step is intended to define interest areas IA[I], IA[J] in the vicinity of the representative contours. The method also includes analyzing the interest areas IA[I], IA[J] being intended to allocate weights W[I], W[J] to the points on the interest areas IA[I], IA[J] and to the points corresponding to the interest areas IA[I], IA[J] on the various images. The method also includes constructing a combination image IM C , a point on the combination image IM C corresponding to a point on at least one interest area IA being obtained from a weighting of the corresponding points on the images to be combined IM[I], IM[J] according to the weights W[I], W[J] allocated in the analysis step ANA.
1. A method for combining ultrasonic images of the same object, the method including:
for each ultrasonic image, seeking a contour representing an interface on the ultrasonic image;
identifying an interest area in each ultrasonic image, the interest area being an enlarged area around the contour;
assigning weights to pixels in the interest areas of the ultrasonic images; and
constructing a combination image from the ultrasonic images, a pixel of the combination image corresponding to a pixel within at least one interest area being obtained from a weighting of the corresponding pixels of the ultrasonic images according to the weights assigned to the corresponding pixels,
wherein the weights are assigned such that when a pixel is within the interest area of more than one of the ultrasonic images, equal weights are assigned to the corresponding pixels for each ultrasonic image for which the pixel is within the interest area, and
wherein the weights are assigned such that when a pixel is within the interest area of a first one of the ultrasonic images, but not within the interest area of a second one of the ultrasonic images, then the weight assigned to the corresponding pixel of the first ultrasonic image is greater than the weight assigned to the corresponding pixel of the second ultrasonic image.
2. A method as claimed in claim 1 , wherein assigning the weights comprises estimating the contrast within at least two interest areas present and similar on at least two of the ultrasonic images, the weights being assigned to the various pixels in said interest areas according to said estimated contrast.
3. The method of claim 2 , wherein the contrast is determined individually for each pixel within each interest area of each ultrasonic image, and the weight assigned to each pixel depends on the individual contrast for that pixel.
4. The method of claim 3 , wherein determining the contrast individually for each pixel within each interest area comprises determining a gradient at the pixel.
5. A method as claimed in claim 1 , wherein at least two of the ultrasonic images have different resolutions and assigning the weights includes evaluating these resolutions within at least two interest areas present and similar on at least two of said ultrasonic images, the weights being assigned to the pixels in said interest areas on said at least two ultrasonic images according to said resolutions.
6. The method of claim 1 , wherein the weights are assigned such that when a pixel is within the interest area of a first one of the ultrasonic images, but not within the interest area of a second one of the ultrasonic images, then the weight assigned to the corresponding pixel of the first ultrasonic image and the weight assigned to the corresponding pixel of the second ultrasonic image are each greater than zero.
7. The method of claim 6 , wherein the weights are assigned such that when a pixel is within the interest area of a first one of the ultrasonic images, but not within the interest area of a second one of the ultrasonic images, then the weight assigned to the corresponding pixel of the first ultrasonic image and the weight assigned to the corresponding pixel of the second ultrasonic image are each less than one.
8. The method of claim 1 , wherein the weights are assigned such that when a plurality of pixels are within the interest area of a first one of the ultrasonic images, but not within the interest area of a second one of the ultrasonic images, then the weights assigned to the plurality of corresponding pixels of the first ultrasonic image that are within the interest area are not all the same as each other, and the weights assigned to the corresponding pixels of the second ultrasonic image that are not within the interest area are not all the same as each other.
9. A method for combining ultrasonic images of the same object, the method including:
obtaining a first ultrasonic image of the object with an ultrasonic array aligned in a first direction and scanned in a second direction perpendicular to the first direction so as to define a first reference plane which is coplanar with the first direction and perpendicular to the second direction, the first ultrasonic image lying in a first image plane having a first angle with respect to the first reference plane;
obtaining a second ultrasonic image of the object by with the ultrasonic array aligned in a third direction and scanned in a fourth direction perpendicular to the third direction so as to define a second reference plane which is coplanar with the third direction and perpendicular to the fourth direction, the second ultrasonic image lying in a second image plane having a second angle with respect to the second reference plane;
for each of the first and second ultrasonic images, seeking a contour representing an interface on the ultrasonic image;
identifying an interest area in each ultrasonic image, the interest area being an enlarged area around the contour;
assigning weights to pixels in the interest areas of the ultrasonic images; and
constructing a combination image from the ultrasonic images, a pixel of the combination image corresponding to a pixel within at least one interest area being obtained from a weighting of the corresponding pixels of the ultrasonic images according to the weights assigned to the corresponding pixels,
wherein the weights are assigned such that when a pixel is within the interest area of the first ultrasonic image and within the interest area of the second ultrasonic image, then the weight assigned to the corresponding pixel in the interest area of the first ultrasonic image is a function of the first angle, and the weight assigned to the corresponding pixel in the interest area of the second ultrasonic image is a function of the second angle.
10. The method of claim 9 , wherein the weights are assigned such that when a pixel is within the interest area of the first ultrasonic image, but not within the interest area of the second ultrasonic image, then the weight assigned to the corresponding pixel of the first ultrasonic image is greater than the weight assigned to the corresponding pixel of the second ultrasonic image.
11. The method of claim 9 , wherein the weight assigned to the corresponding pixel in the interest area of the first ultrasonic image is a function of a cosine of the first angle, and the weight assigned to the corresponding pixel in the interest area of the second ultrasonic image is a function of a cosine of the second angle.
12. The method of claim 9 , wherein the weight assigned to the corresponding pixel in the interest area of the first ultrasonic image increases as the first angle increases, and the weight assigned to the corresponding pixel in the interest area of the second ultrasonic image increases as the second angle increases.