在3D RGB numpy数组中设置屏蔽像素

时间:2013-11-19 20:32:27

标签: python arrays numpy

我想使用蒙版在3d numpy数组(RGB图像)中设置匹配某些条件的所有像​​素。我有这样的事情:

def make_dot(img, color, radius):
    """Make a dot of given color in the center of img (rgb numpy array)"""
    (ydim,xdim,dummy) = img.shape
    # make an open grid of x,y
    y,x = np.ogrid[0:ydim, 0:xdim, ]
    y -= ydim/2                 # centered at the origin
    x -= xdim/2
    # now make a mask
    mask = x**2+y**2 <= radius**2 # start with 2d
    mask.shape = mask.shape + (1,) # make it 3d
    print img[mask].shape
    img[mask] = color

img = np.zeros((100, 200, 3))
make_dot(img, np.array((.1, .2, .3)), 25)

但在此行中提供ValueError: array is not broadcastable to correct shape

img[mask] = color

因为img [mask]的形状是(1961,);即,它被展平为仅包含“有效”像素,这是有道理的;但是我怎么能让它“通过掩码写入”,因为它只设置掩码为1的像素?请注意,我想一次向每个像素写入三个值(最后一个暗淡)。

1 个答案:

答案 0 :(得分:5)

你几乎是对的。

(ydim,xdim,dummy) = img.shape
# make an open grid of x,y
y,x = np.ogrid[0:ydim, 0:xdim, ]
y -= ydim/2                 # centered at the origin
x -= xdim/2
# now make a mask
mask = x**2+y**2 <= radius**2 # start with 2d
img[mask,:] = color

分配结尾处的额外“,:”可让您一次性在3个通道中分配颜色。