[英]OpenCV putText() new line character
我正在使用 cv2.putText() 在圖像上繪制文本字符串。
當我寫:
cv2.putText(img, "This is \n some text", (50,50), cv2.FONT_HERSHEY_SIMPLEX, 1, 2)
圖片上繪制的文字是:
This is? some text
我期待文本打印在新行中,因為\n
是換行符的轉義字符,但它會繪制?
而是在圖像上。
為什么會這樣? 難道我做錯了什么?
不幸的是putText
不能正確處理\\n
符號。 請參閱相關的拒絕拉取請求。 您需要自己拆分文本並進行幾次putText
調用,例如:
text = "This is \n some text"
y0, dy = 50, 4
for i, line in enumerate(text.split('\n')):
y = y0 + i*dy
cv2.putText(img, line, (50, y ), cv2.FONT_HERSHEY_SIMPLEX, 1, 2)
這是另一個例子:
https://gist.github.com/EricCousineau-TRI/596f04c83da9b82d0389d3ea1d782592
基本上,與 elyase 的答案相同,但也使用getTextSize()
(盡管我不得不將行大小增加到比預期大一點)。
elyase 提出的方法在 OpenCV 4.5.1.38 中對我很有效。 我確實驗證了文本字符串仍然可以用“+”連接,並且可以使用“str(value)”插入數值。 換行符的開頭只是加上“\\n”,一切都按預期進行。
y0, dy, text = 185,50, "FPS: "+str(framerate)+"\nMIN: "+str(frMIN)+"\nMAX: "+str(frMAX)+"\nAVG: "+str(frAVG)
for i, line in enumerate(text.split('\n')):
y = y0 + i*dy
cv2.putText(currStack, line, (50, y ), cv2.FONT_HERSHEY_SIMPLEX, 1, (0, 0, 255), 2, cv2.LINE_AA, False)
我為這個海豚寫了一個實用程序 function:
from typing import Optional, Tuple
import cv2
import numpy as np
def add_text_to_image(
image_rgb: np.ndarray,
label: str,
top_left_xy: Tuple = (0, 0),
font_scale: float = 1,
font_thickness: float = 1,
font_face=cv2.FONT_HERSHEY_SIMPLEX,
font_color_rgb: Tuple = (0, 0, 255),
bg_color_rgb: Optional[Tuple] = None,
outline_color_rgb: Optional[Tuple] = None,
line_spacing: float = 1,
):
"""
Adds text (including multi line text) to images.
You can also control background color, outline color, and line spacing.
outline color and line spacing adopted from: https://gist.github.com/EricCousineau-TRI/596f04c83da9b82d0389d3ea1d782592
"""
OUTLINE_FONT_THICKNESS = 3 * font_thickness
im_h, im_w = image_rgb.shape[:2]
for line in label.splitlines():
x, y = top_left_xy
# ====== get text size
if outline_color_rgb is None:
get_text_size_font_thickness = font_thickness
else:
get_text_size_font_thickness = OUTLINE_FONT_THICKNESS
(line_width, line_height_no_baseline), baseline = cv2.getTextSize(
line,
font_face,
font_scale,
get_text_size_font_thickness,
)
line_height = line_height_no_baseline + baseline
if bg_color_rgb is not None and line:
# === get actual mask sizes with regard to image crop
if im_h - (y + line_height) <= 0:
sz_h = max(im_h - y, 0)
else:
sz_h = line_height
if im_w - (x + line_width) <= 0:
sz_w = max(im_w - x, 0)
else:
sz_w = line_width
# ==== add mask to image
if sz_h > 0 and sz_w > 0:
bg_mask = np.zeros((sz_h, sz_w, 3), np.uint8)
bg_mask[:, :] = np.array(bg_color_rgb)
image_rgb[
y : y + sz_h,
x : x + sz_w,
] = bg_mask
# === add outline text to image
if outline_color_rgb is not None:
image_rgb = cv2.putText(
image_rgb,
line,
(x, y + line_height_no_baseline), # putText start bottom-left
font_face,
font_scale,
outline_color_rgb,
OUTLINE_FONT_THICKNESS,
cv2.LINE_AA,
)
# === add text to image
image_rgb = cv2.putText(
image_rgb,
line,
(x, y + line_height_no_baseline), # putText start bottom-left
font_face,
font_scale,
font_color_rgb,
font_thickness,
cv2.LINE_AA,
)
top_left_xy = (x, y + int(line_height * line_spacing))
return image_rgb
以下是示例結果:
image = 200 * np.ones((550, 410, 3), dtype=np.uint8)
image = add_text_to_image(
image,
"Testing \nDouble new line\n\nLine too longggggggggggggggggggggg",
)
image = add_text_to_image(
image,
"Testing with font scale",
font_scale=0.5,
font_color_rgb=(0, 255, 0),
top_left_xy=(0, 150),
)
image = add_text_to_image(
image,
"Testing with bg \nDouble new line\n\nLine too longggggggggggggggggggggg",
bg_color_rgb=(255, 255, 255),
font_color_rgb=(255, 0, 0),
top_left_xy=(0, 200),
)
image = add_text_to_image(
image,
"Testing with line specing\nand outline",
font_color_rgb=(0, 255, 255),
outline_color_rgb=(0, 0, 0),
top_left_xy=(0, 350),
line_spacing=1.5,
)
import matplotlib.pyplot as plt
plt.imshow(image)
plt.show()
如果要將多行數據添加到視頻幀中,則必須添加多行putText(),即使上述帶for循環的答案僅適用於圖像,而不適用於創建視頻時通過代碼。
您可以做的是在python中使用“ exec”函數,該函數將字符串作為輸入並將其呈現到代碼中。
因此,我建議通過使用for循環附加所有行來創建一個小的python代碼段作為字符串,並在所需的位置執行它,它也將顯示在不同的位置。 這種情況對我來說可以為視頻添加數據。
stringexec = ""
m=0
for i in TextList:
stringexec = steval+"cv2.putText(frame, TextList[" + str(TextList.index(i))+"], (100, 100+"+str(m)+"), cv2.FONT_HERSHEY_COMPLEX, 0.5, (200, 100, 100), 1, cv2.LINE_AA)\n"
m += 100
exec(stringexec)
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