python - 在 Python 中以一定角度(旋转)绘制文本

Question

我正在将文本绘制到 numpy 上Python 中的数组图像(使用自定义字体)。目前我正在将图像转换为 PIL，绘制文本，然后再转换回 numpy 数组。

import numpy as np
import cv2

from PIL import Image
from PIL import ImageDraw
from PIL import ImageFont

char_image = np.zeros((200, 300, 3), np.uint8)

# convert to pillow image
pillowImage = Image.fromarray(char_image)
draw = ImageDraw.Draw(pillowImage)

# add chars to image
font = ImageFont.truetype("arial.ttf", 32)
draw.text((50, 50), 'ABC', (255, 255, 255), font=font)

# convert back to numpy array
char_image = np.array(pillowImage, np.uint8)

# show image on screen
cv2.imshow('myImage', char_image)
cv2.waitKey(0)

有没有办法在给定的角度上绘制文本，即。 33 度？

不能在绘制完文本后旋转图像

Answer 1

您可以使用 PIL 绘制旋转文本。我建议将文本绘制到空白图像上，旋转该图像，然后将旋转后的图像粘贴到主图像中。像这样的东西:

代码:

def draw_rotated_text(image, angle, xy, text, fill, *args, **kwargs):
    """ Draw text at an angle into an image, takes the same arguments
        as Image.text() except for:

    :param image: Image to write text into
    :param angle: Angle to write text at
    """
    # get the size of our image
    width, height = image.size
    max_dim = max(width, height)

    # build a transparency mask large enough to hold the text
    mask_size = (max_dim * 2, max_dim * 2)
    mask = Image.new('L', mask_size, 0)

    # add text to mask
    draw = ImageDraw.Draw(mask)
    draw.text((max_dim, max_dim), text, 255, *args, **kwargs)

    if angle % 90 == 0:
        # rotate by multiple of 90 deg is easier
        rotated_mask = mask.rotate(angle)
    else:
        # rotate an an enlarged mask to minimize jaggies
        bigger_mask = mask.resize((max_dim*8, max_dim*8),
                                  resample=Image.BICUBIC)
        rotated_mask = bigger_mask.rotate(angle).resize(
            mask_size, resample=Image.LANCZOS)

    # crop the mask to match image
    mask_xy = (max_dim - xy[0], max_dim - xy[1])
    b_box = mask_xy + (mask_xy[0] + width, mask_xy[1] + height)
    mask = rotated_mask.crop(b_box)

    # paste the appropriate color, with the text transparency mask
    color_image = Image.new('RGBA', image.size, fill)
    image.paste(color_image, mask)

它是如何工作的:

1. 创建一个透明蒙版。
2. 将文本绘制到 mask 上。
3. 旋转蒙版，裁剪到合适的大小。
4. 使用包含文本的旋转透明蒙版，将所需颜色粘贴到图像中。

测试代码:

import numpy as np

from PIL import Image
from PIL import ImageDraw
from PIL import ImageFont

char_image = np.zeros((100, 150, 3), np.uint8)

# convert to pillow image
pillowImage = Image.fromarray(char_image)

# draw the text
font = ImageFont.truetype("arial.ttf", 32)
draw_rotated_text(pillowImage, 35, (50, 50), 'ABC', (128, 255, 128), font=font)

pillowImage.show()

结果: