diff options
Diffstat (limited to 'fg21sim/utils')
| -rw-r--r-- | fg21sim/utils/transform.py | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/fg21sim/utils/transform.py b/fg21sim/utils/transform.py index 3a3e541..63fad94 100644 --- a/fg21sim/utils/transform.py +++ b/fg21sim/utils/transform.py @@ -18,6 +18,7 @@ References import numpy as np import numba as nb +from scipy import ndimage @nb.jit([nb.float64[:, :](nb.int64[:, :], nb.float64, nb.boolean, @@ -141,3 +142,42 @@ def rotate_center(imgin, angle, interp=True, reshape=True, fill_value=0.0): # imgout[rr, cc] = p_val return imgout + + +def circle2ellipse(imgcirc, bfraction, rotation=0.0): + """ + Shrink the input circle image with respect to the center along the + column (axis) to transform the circle to an ellipse, and then rotate + around the image center. + + Parameters + ---------- + imgcirc : 2D `~numpy.ndarray` + Input image grid containing a circle at the center + bfraction : float + The fraction of the semi-minor axis w.r.t. the semi-major axis + (assumed to be the width of the input image), to determine the + shrunk size (height) of the output image. + Should be a fraction within [0, 1] + rotation : float, optional + Rotation angle (unit: [ degree ]) + + Returns + ------- + imgout : 2D `~numpy.ndarray` + Image of the same size as the input circle image. + """ + nrow, ncol = imgcirc.shape + # Shrink the circle to be elliptical + nrow2 = nrow * bfraction + nrow2 = int(nrow2 / 2) * 2 + 1 # be odd + img2 = ndimage.zoom(imgcirc, zoom=(nrow2/nrow, 1.0), order=1) + # Pad the shrunk image to have the same size as input + imgout = np.zeros(shape=(nrow, ncol)) + r1 = int((nrow - nrow2) / 2) + r2 = r1 + nrow2 + imgout[r1:r2, :] = img2 + # Rotate the ellipse + imgout = ndimage.rotate(imgout, angle=rotation, reshape=False, + order=1) + return imgout |