参考:https://blog.csdn.net/haveanybody/article/details/86494063

基础

cv2 打开图片，tensor的shape是（im_height, im_width, channel），BGR格式。cv2.imread返回的是numpy.ndarray张量。

pillow 打开图片，RGB格式。Pillow读出来的是PIL.Image.Image对象。

打开图片与保存图片

python
##PIL 读取、保存图片方法
from PIL import Image
img = Image.open("eee.jpg")
img.save("eee_result.jpg")
##cv2 读取、保存图片方法
import cv2
img = cv2.imread("eee.jpg")
cv2.imwrite("eee_result.jpg", img)
##图片文件打开为base64
import base64
def img_base64(img_path):
    with open(img_path, "rb") as f:
        base64_str = base64.b64encode(f.read())
    return base64_str

CV2中的 BGR转RGB

python
from matplotlib import pyplot as plt
import cv2
img = cv2.imread("eee.jpg")
cv2.imwrite("eee_result.jpg", img)
imgrgb = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
plt.imshow(imgrgb)
plt.show()

PIL CV2 的相互转换

python
## PIL转cv2
import cv2
from PIL import Image
import numpy as np
img_rgb = Image.open("eee.jpg")
img_bgr = cv2.cvtColor(np.asarray(img_rgb), cv2.COLOR_RGB2BGR) # 成为cv2的numpy.ndarray

python
## PIL转cv2
import cv2
from PIL import Image
img_bgr = cv2.imread("eee.jpg")
img_rgb = Image.fromarray(cv2.cvtColor(img_bgr, cv2.COLOR_BGR2RGB)) # 成为Pillow的PIL.Image.Image对象

PIL base64 的相互转换

python
##PIL转base64
import base64
from io import BytesIO
from PIL import Image
def pillow_to_base64(image):
    img_buffer = BytesIO()
    image.save(img_buffer, format='JPEG')
    byte_data = img_buffer.getvalue()
    base64_str = base64.b64encode(byte_data)
    return base64_str
# example
img = Image.open("eee.jpg")
print(pillow_to_base64(img))

python
##PIL转base64
import base64
from io import BytesIO
from PIL import Image
def base64_to_pillow(base64_str):
    image = base64.b64decode(base64_str)
    image = BytesIO(image)
    image = Image.open(image)
    return image
# example
with open("eee.jpg", "rb") as f:
    base64_str = base64.b64encode(f.read())
print(base64_to_pillow(base64_str))

CV2 base64 的相互转换

python
# cv2 转 base64
import base64
import cv2
def cv2_to_base64(image):
    base64_str = cv2.imencode('.jpg', image)[1].tostring()
    base64_str = base64.b64encode(base64_str)
    return base64_str
# example
image = cv2.imread("eee.jpg")
print(cv2_to_base64(image))

python
# base64 转 cv2
import base64
import numpy as np
import cv2
from PIL import Image
from io import BytesIO
def base64_to_cv2(base64_str):
    imgString = base64.b64decode(base64_str)
    nparr = np.frombuffer(imgString, np.uint8)
    image = cv2.imdecode(nparr, cv2.IMREAD_COLOR)
    return image
# example
with open("eee.jpg", "rb") as f:
    base64_str = base64.b64encode(f.read())
print(base64_to_cv2(base64_str))

FastAPI中bytes 转CV2

python
img = cv2.imdecode(np.frombuffer(file, dtype=np.uint8), cv2.IMREAD_COLOR)

FastAPI中uploadfile 转CV2

python
img = cv2.imdecode(np.fromstring(fileb.file.read(), np.uint8), cv2.IMREAD_COLOR)

CV2 numpy 转成 字节流（open("file.jpg",'rb')）

参考：https://blog.csdn.net/sinat_29957455/article/details/107208432

python
img = cv2.imread("lpr1.png")
# 对数组的图片格式进行编码
success, encoded_image = cv2.imencode(".jpg", img)
# 将数组转为bytes
f = encoded_image.tobytes()