We use the functions: cv.warpPerspective (src, dst, M, dsize, flags = cv.INTER_LINEAR, borderMode = cv.BORDER_CONSTANT, borderValue = new cv.Scalar()) Parameters src Then apply cv.warpPerspective with this 3x3 transformation matrix. Then transformation matrix can be found by the function cv.getPerspectiveTransform. Among these 4 points, 3 of them should not be collinear. To find this transformation matrix, you need 4 points on the input image and corresponding points on the output image. Straight lines will remain straight even after the transformation. Three corresponding points( size and cv.CV_32FC2 type) in output image.įor perspective transformation, you need a 3x3 transformation matrix. Three points( size and cv.CV_32FC2 type) from input imag. We use the function: cv.getAffineTransform (src, dst) Parameters src Then cv.getAffineTransform will create a 2x3 matrix which is to be passed to cv.warpAffine. To find the transformation matrix, we need three points from input image and their corresponding locations in output image. In affine transformation, all parallel lines in the original image will still be parallel in the output image. Positive values mean counter-clockwise rotation (the coordinate origin is assumed to be the top-left corner). We use the function: cv.getRotationMatrix2D (center, angle, scale) Parameters centerĬenter of the rotation in the source image. If you know the shift in (x,y) direction, let it be \((t_x,t_y)\), you can create the transformation matrix \(\textbf\] Translation is the shifting of object's location. Interpolation method(see cv.InterpolationFlags) Scale factor along the vertical axis when it equals 0, it is computed as Scale factor along the horizontal axis when it equals 0, it is computed as \Įither dsize or both fx and fy must be non-zero. Output image size if it equals zero, it is computed as: Output image it has the size dsize (when it is non-zero) or the size computed from src.size(), fx, and fy the type of dst is the same as of src. We use the function: cv.resize (src, dst, dsize, fx = 0, fy = 0, interpolation = cv.INTER_LINEAR) Parameters src Preferable interpolation methods are cv.INTER_AREA for shrinking and cv.INTER_CUBIC (slow)
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