基于Python实现二维图像双线性插值

def bilinear_by_meshgrid(image, x_grid, y_grid):

    #               Ia, Wd                          Ic, Wb
    #           (floor_x, floor_y)              (ceil_x, floor_y)   
    #
    #                               (x, y)
    #
    #               Ib , Wc                         Id, Wa
    #           (floor_x, ceil_y)               (ceil_x, ceil_y)   
    #

    assert image.shape == x_grid.shape == y_grid.shape
    assert image.ndim == 2
    H, W = image.shape[:2]

    floor_x_grid = np.floor(x_grid).astype('int32')
    floor_y_grid = np.floor(y_grid).astype('int32')
    ceil_x_grid = floor_x_grid + 1
    ceil_y_grid = floor_y_grid + 1

    if np.max(ceil_x_grid) > W -1 or  np.max(ceil_y_grid) > H -1 or np.min(floor_x_grid) < 0 or np.min(floor_y_grid) < 0:
        print("Warning: index value out of original matrix, a crop operation will be applied.")

        floor_x_grid = np.clip(floor_x_grid, 0, W-1).astype('int32')
        ceil_x_grid = np.clip(ceil_x_grid, 0, W-1).astype('int32')
        floor_y_grid = np.clip(floor_y_grid, 0, H-1).astype('int32')
        ceil_y_grid = np.clip(ceil_y_grid, 0, H-1).astype('int32')

    Ia = image[ floor_y_grid, floor_x_grid ]
    Ib = image[ ceil_y_grid, floor_x_grid ]
    Ic = image[ floor_y_grid, ceil_x_grid ]
    Id = image[ ceil_y_grid, ceil_x_grid ]

    wa = (ceil_x_grid - x_grid) * (ceil_y_grid - y_grid)
    wb = (ceil_x_grid - x_grid) * (y_grid - floor_y_grid)
    wc = (x_grid - floor_x_grid) * (ceil_y_grid - y_grid)
    wd = (x_grid - floor_x_grid) * (y_grid - floor_y_grid)

    assert np.min(wa) >=0 and np.min(wb) >=0 and np.min(wc) >=0 and np.min(wd) >=0
    
    W = wa + wb + wc + wd
    assert np.sum(W[:, -1]) + np.sum(W[-1, :]) == 0
    
    wa[:-1, -1] = ceil_y_grid[:-1, -1] - y_grid[:-1, -1]
    wb[:-1, -1] = y_grid[:-1, -1] - floor_y_grid[:-1, -1]
    
    wb[-1, :-1] = ceil_x_grid[-1, :-1] - x_grid[-1, :-1]
    wd[-1, :-1] = x_grid[-1, :-1] - floor_x_grid[-1, :-1]
    
    wd[-1, -1] = 1
    
    W = wa + wb + wc + wd
    assert np.max(W) == np.min(W) == 1
    
    res_image = wa*Ia + wb*Ib + wc*Ic + wd*Id

    return res_image

pip install mtutils

from mtutils import bilinear_by_meshgrid