[OpenCV] 以最亮顏色的色相來進行灰階處理

OpenCV-Python 教學 https://docs.opencv.org/3.4.16/d6/d00/tutorial_py_root.html

原始圖片

原圖因為燈光散射的關係，整個圖片都出現發紅的現象

預設灰階 cv2.imread('01.jpg', cv2.IMREAD_GRAYSCALE)

有部分的色差變得不明顯，之後要進行辨識變得很困難

色相比例的灰階

透過色相的方式就好很多

HSV 的數值定義

• H: 色相 0~360度
• S: 飽和度 0~1
• V: 明度 (黑)0~1(白)

OpenCV HSV 的數值定義

• H: 0 ~ 180 => H / 2
• S: 0 ~ 255 => S * 255
• V: 0 ~ 255 => V * 255

相依套件:

pip install opencv-python
pip install py-linq     # https://viralogic.github.io/py-enumerable/

程式:

from py_linq import Enumerable
import cv2
import numpy as np


def get_hue(img):
    ''' 圖片色相 '''

    img = cv2.resize(img, (32, 32), interpolation = cv2.INTER_LINEAR)
    img_hsv = cv2.cvtColor(img, cv2.COLOR_BGR2HSV)
    pixel_hsv = np.reshape(img_hsv,(-1,3))

    result = Enumerable(pixel_hsv)\
        .order_by_descending(lambda p: p[2])\
        .then_by_descending(lambda p: p[1])\
        .first()

    print(f'[result]: {result}')
    return result[0]



def get_gray_rate(hue):
    ''' 根據色相計算灰階比例 '''

    hue_full = np.uint8([[[hue,255,255]]])
    hue_bgr = cv2.cvtColor(hue_full, cv2.COLOR_HSV2BGR)
    (hue_b, hue_g, hue_r) = hue_bgr[0,0]

    hue_total =  0.0 + hue_b + hue_g + hue_r

    return [
        hue_b / hue_total,
        hue_g / hue_total,
        hue_r / hue_total,
    ]



img = cv2.imread('01.jpg')

hue = get_hue(img)
gray_rate = get_gray_rate(hue) # 灰階比例

print(f'hue:{hue}, gray_rate: {gray_rate}')

# 灰階轉換
img_gray = cv2.transform(img, np.array([gray_rate]))

cv2.imshow("img", img)
cv2.imshow("img_gray", img_gray)
cv2.waitKey(0)
cv2.destroyAllWindows()

[Python] Flask Log 配置

import os
import logging
import logging.handlers

from flask import Flask, g, request, json

app = Flask(__name__)


#[ Log 配置 ]#############################################################
 # 用來記錄無法處理的錯誤 (PS: 使用 WSGI 會依附 Apache 的設定，可以不用配置)

# https://docs.python.org/zh-cn/3/library/logging.html
formatter = logging.Formatter("%(asctime)s [%(levelname)s]  %(message)s")

# https://docs.python.org/zh-tw/3/library/logging.handlers.html#timedrotatingfilehandler
handler = logging.handlers.TimedRotatingFileHandler("log/web-api",
    when = "D",
    interval = 1,
    backupCount = 7,
    encoding = "UTF-8",
    delay = False,
    utc = True)
handler.setFormatter(formatter)

app.logger.addHandler(handler)

[Python] Flask 自訂日期的 Json 轉換

import os
import datetime
import time

from flask import Flask, g, request, json
from flask.json import JSONEncoder


class CustomJsonEncoder(JSONEncoder):
    # 針對日期自訂 Json 轉換

    def default(self, obj):
        if isinstance(obj, datetime.date):
            return obj.isoformat().replace('T', ' ')

        return super().default(obj)


app = Flask(__name__)

app.json_encoder = CustomJsonEncoder
app.config['JSON_AS_ASCII'] = False  # 返回結果可以正確顯示中文

[Python] Flask MySQL 連線管理

import os
import mysql.connector as sql

from werkzeug.exceptions import HTTPException, BadRequest
from flask import Flask, g, request, json


app = Flask(__name__)



#[ DB 處裡 ]#############################################################

# https://docsxyz.com/zh-hant/wiki/python/connector-python-connectargs
db_config = {
    'host'      : "localhost",
    'user'      : "XXXX",
    'passwd'    : "XXXX",
    'db'        : 'XXXX',
    'use_pure'  : True,
    'autocommit': True,
    'charset'   : 'utf8',
}


@app.before_request
def before_request():
    # 在 request 前開啟 DB 連線
    # g 是 Flask global 在每個 request 有獨立的 context

    g.cnt = sql.connect(**db_config)
    g.cursor = g.cnt.cursor(dictionary = True)



@app.after_request
def after_request(response):
    # 在 request 後結束 DB 連線

    cursor = g.get('cursor', None)
    if cursor is not None:
        # 當 cursor 還有 row 沒有取出，close 會發生錯誤
        if cursor.with_rows : cursor.fetchall()
        cursor.close()

    cnt = g.get('cnt', None)
    if cnt is not None:
        cnt.close()

    return response

[Python] Flask 筆記

相依套件：

-------------------------------------------------------------------------------

python-3.8.10-amd64.exe

pip install Flask

pip install flask_cors

pip install mysql-connector-python

pip install pycryptodomex

pip install py-linq     # https://viralogic.github.io/py-enumerable/

Apache CGI 配置，用虛擬 Script 指向到 app.cgi

-------------------------------------------------------------------------------

https://dormousehole.readthedocs.io/en/latest/deploying/cgi.html

https://flask.palletsprojects.com/en/2.0.x/deploying/cgi/

ScriptAlias /web-api  D:/iog-project/web-api/app.cgi

<Directory "D:/iog-project/web-api/">

Options ExecCGI 

AllowOverride all

Require local

</Directory>

執行程式  https://www.maxlist.xyz/2020/04/30/flask-helloworld/

-------------------------------------------------------------------------------

# 正常執行

flask run

# 除錯執行  (flask 會提供除錯功能，並將 logger 從 warning 提升到 debug 

export FLASK_ENV=development    # for linux / git  bash 

set FLASK_ENV=development       # for windows cmd

flask run

# 列出設定的路徑

flask routes

其他

-------------------------------------------------------------------------------

因為 web-api 的格式是 Json，所以遵照 JS 的命名風格，欄位名稱開頭小寫第二個字大寫

[Python] Flask 錯誤處裡

from werkzeug.exceptions import HTTPException, BadRequest
from flask import Flask, g, request, json

app = Flask(__name__)


#[ 錯誤處裡 ]#############################################################
@app.errorhandler(Exception)
def handle_exception(e):
    if isinstance(e, HTTPException): return e  # 讓 HTTPException 交由下一個處理

    app.logger.exception("Internal Server Error.")  # log 錯誤訊息
    if app.debug : return e

    return json.jsonify({'message': 'Internal Server Error.'}), 500


@app.errorhandler(HTTPException)
def handle_exception(e):
    response = e.get_response()
    return json.jsonify({'message': e.description}), e.code