cv2.error: OpenCV(4.5.5) D:\a\opencv-python\imgproc\src\color.cpp:182: error: (-215:Assertion failed) !_src.empty() in function 'cv::cvtColor'

Question

I think i have written in right way but still i am facing this error.could you please help me the Error is as follows- Exception in Tkinter callback Traceback (most recent call last): File "C:\Users\swpr4\AppData\Local\Programs\Python\Python310\lib\tkinter_ init _.py", line 1921, in call return self.func(*args) File "c:\Users\swpr4\OneDrive\Desktop\face_recognition system\face_recognition.py", line 109, in face_recog img=recognize(img,clf,faceCascade) File "c:\Users\swpr4\OneDrive\Desktop\face_recognition system\face_recognition.py", line 98, in recognize coord=draw_boundray(img,faceCascade,1.1,10,(255,25,255),"Face",clf) File "c:\Users\swpr4\OneDrive\Desktop\face_recognition system\face_recognition.py", line 49, in draw_boundray gray_image=cv2.cvtColor(img,cv2.COLOR_BGR2GRAY) cv2.error: OpenCV(4.5.5) D:\a\opencv-python\opencv-python\opencv\modules\imgproc\src\color.cpp:182: error: (-215:Assertion failed) !_src.empty() in function 'cv::cvtColor'

from tkinter import*
# from tkinter import ttk
from PIL import Image,ImageTk
from tkinter import messagebox
import cv2
import os
import numpy as np
import mysql.connector





class Face_recognition:  
    def __init__(self,root):
        self.root=root
        self.root.geometry("1540x790+0+0")
        self.root.title("face Recognition System")

        title_lbl=Label(self.root,text="FACE RECOGNITION",font=("times new roman",35,"bold"),bg="white",fg="red")
        title_lbl.place(x=0,y=0,width=1530,height=45)


        # 1st image
        img_top=Image.open(r"college_images\face_detector1.jpg")
        img_top=img_top.resize((650,700),Image.ANTIALIAS)
        self.photoimg_top=ImageTk.PhotoImage(img_top)

        f_lbl=Label(self.root,image=self.photoimg_top)
        f_lbl.place(x=0,y=55,width=650,height=700)

        # 2nd image

        img_bottom=Image.open(r"college_images\facial_recognition_system_identification_digital_id_security_scanning_thinkstock_858236252_3x3-100740902-large.jpg")
        img_bottom=img_bottom.resize((950,700),Image.ANTIALIAS)
        self.photoimg_bottom=ImageTk.PhotoImage(img_bottom)

        f_lbl=Label(self.root,image=self.photoimg_bottom)
        f_lbl.place(x=650,y=55,width=950,height=700)

        #button
        b1_1=Button(f_lbl,text="Face Recognition",command=self.face_recog, cursor="hand2",font=("times new roman",18,"bold"),bg="red",fg="white")
        b1_1.place(x=365,y=620,width=200,height=40)

    #==========================face recognition =============================#

    def face_recog(self):
        def draw_boundray(img,classifier,scaleFactor,minNeighbors,color,text,clf):
            gray_image=cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
            feature=classifier.detectMultiScale(gray_image,scaleFactor,minNeighbors)

            coord=[]

            for(x,y,w,h) in feature:
                cv2.rectangle(img,(x,y),(x+w,y+h),(0,255,0),3)
                id,predict=clf.predict(gray_image[y:y+h,x:x+w])
                confidence=int((100*(1-predict/300)))

                conn=mysql.connector.connect(host="localhost",username="root",password="root1234",database="face_recognizer")
                my_cursor=conn.cursor()

                my_cursor.execute("select Name from student where Student_Id="+str(id))
                n=my_cursor.fetchone()
                n="+".join(n)

                my_cursor.execute("select Roll from student where Student_Id="+str(id))
                r=my_cursor.fetchone()
                r="+".join(r)

                my_cursor.execute("select Dep from student where Student_Id="+str(id))
                d=my_cursor.fetchone()
                d="+".join(d)

                # my_cursor.execute("select Division from student where Student_Id="+str(id))
                # di=my_cursor.fetchone()
                # di="+".join(di)

                 

                if confidence>77:
                    cv2.putText(img,f"Roll:{r}",(x,y-55),cv2.FONT_HERSHEY_COMPLEX,0.8,(255,255,255),3)

                    cv2.putText(img,f"Name:{n}",(x,y-30),cv2.FONT_HERSHEY_COMPLEX,0.8,(255,255,255),3)

                    cv2.putText(img,f"Department:{d}",(x,y-5),cv2.FONT_HERSHEY_COMPLEX,0.8,(255,255,255),3)

                    #cv2.putText(img,f"Division:{di}",(x,y-5),cv2.FONT_HERSHEY_COMPLEX,0.8,(255,255,255),3)
                
                else:
                    cv2.rectangle(img,(x,y),(x+w,y+h),(0,0,255),3)
                    cv2.putText(img,"Unknown Face",(x,y-5),cv2.FONT_HERSHEY_COMPLEX,0.8,(255,255,255),3)

                coord=[x,y,w,h]

            return coord

        def recognize(img,clf,faceCascade):
            coord=draw_boundray(img,faceCascade,1.1,10,(255,25,255),"Face",clf)
            return img

        faceCascade=cv2.CascadeClassifier("haarcascade_frontalface_default.xml")
        clf=cv2.face.LBPHFaceRecognizer_create()
        clf.read("classifire.xml")

        video_cap=cv2.VideoCapture(0)

        while True:
            ret,img=video_cap.read()
            img=recognize(img,clf,faceCascade)
            cv2.imshow("Welcome To Face Recognition",img)

            if cv2.waitKey(1)==13:
                break
            video_cap.release()
            cv2.destroyAllWindows()


if __name__ == "__main__":
    root=Tk()
    obj=Face_recognition(root)
    root.mainloop()

from tkinter import*
# from tkinter import ttk
from PIL import Image,ImageTk
from tkinter import messagebox
import cv2
import os
import numpy as np
import mysql.connector





class Face_recognition:  
    def __init__(self,root):
        self.root=root
        self.root.geometry("1540x790+0+0")
        self.root.title("face Recognition System")

        title_lbl=Label(self.root,text="FACE RECOGNITION",font=("times new roman",35,"bold"),bg="white",fg="red")
        title_lbl.place(x=0,y=0,width=1530,height=45)


        # 1st image
        img_top=Image.open(r"college_images\face_detector1.jpg")
        img_top=img_top.resize((650,700),Image.ANTIALIAS)
        self.photoimg_top=ImageTk.PhotoImage(img_top)

        f_lbl=Label(self.root,image=self.photoimg_top)
        f_lbl.place(x=0,y=55,width=650,height=700)

        # 2nd image

        img_bottom=Image.open(r"college_images\facial_recognition_system_identification_digital_id_security_scanning_thinkstock_858236252_3x3-100740902-large.jpg")
        img_bottom=img_bottom.resize((950,700),Image.ANTIALIAS)
        self.photoimg_bottom=ImageTk.PhotoImage(img_bottom)

        f_lbl=Label(self.root,image=self.photoimg_bottom)
        f_lbl.place(x=650,y=55,width=950,height=700)

        #button
        b1_1=Button(f_lbl,text="Face Recognition",command=self.face_recog, cursor="hand2",font=("times new roman",18,"bold"),bg="red",fg="white")
        b1_1.place(x=365,y=620,width=200,height=40)

    #==========================face recognition =============================#

    def face_recog(self):
        def draw_boundray(img,classifier,scaleFactor,minNeighbors,color,text,clf):
            gray_image=cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
            feature=classifier.detectMultiScale(gray_image,scaleFactor,minNeighbors)

            coord=[]

            for(x,y,w,h) in feature:
                cv2.rectangle(img,(x,y),(x+w,y+h),(0,255,0),3)
                id,predict=clf.predict(gray_image[y:y+h,x:x+w])
                confidence=int((100*(1-predict/300)))

                conn=mysql.connector.connect(host="localhost",username="root",password="root1234",database="face_recognizer")
                my_cursor=conn.cursor()

                my_cursor.execute("select Name from student where Student_Id="+str(id))
                n=my_cursor.fetchone()
                n="+".join(n)

                my_cursor.execute("select Roll from student where Student_Id="+str(id))
                r=my_cursor.fetchone()
                r="+".join(r)

                my_cursor.execute("select Dep from student where Student_Id="+str(id))
                d=my_cursor.fetchone()
                d="+".join(d)

                # my_cursor.execute("select Division from student where Student_Id="+str(id))
                # di=my_cursor.fetchone()
                # di="+".join(di)

                 

                if confidence>77:
                    cv2.putText(img,f"Roll:{r}",(x,y-55),cv2.FONT_HERSHEY_COMPLEX,0.8,(255,255,255),3)

                    cv2.putText(img,f"Name:{n}",(x,y-30),cv2.FONT_HERSHEY_COMPLEX,0.8,(255,255,255),3)

                    cv2.putText(img,f"Department:{d}",(x,y-5),cv2.FONT_HERSHEY_COMPLEX,0.8,(255,255,255),3)

                    #cv2.putText(img,f"Division:{di}",(x,y-5),cv2.FONT_HERSHEY_COMPLEX,0.8,(255,255,255),3)
                
                else:
                    cv2.rectangle(img,(x,y),(x+w,y+h),(0,0,255),3)
                    cv2.putText(img,"Unknown Face",(x,y-5),cv2.FONT_HERSHEY_COMPLEX,0.8,(255,255,255),3)

                coord=[x,y,w,h]

            return coord

        def recognize(img,clf,faceCascade):
            coord=draw_boundray(img,faceCascade,1.1,10,(255,25,255),"Face",clf)
            return img

        faceCascade=cv2.CascadeClassifier("haarcascade_frontalface_default.xml")
        clf=cv2.face.LBPHFaceRecognizer_create()
        clf.read("classifire.xml")

        video_cap=cv2.VideoCapture(0)

        while True:
            ret,img=video_cap.read()
            img=recognize(img,clf,faceCascade)
            cv2.imshow("Welcome To Face Recognition",img)

            if cv2.waitKey(1)==13:
                break
            video_cap.release()
            cv2.destroyAllWindows()


if __name__ == "__main__":
    root=Tk()
    obj=Face_recognition(root)
    root.mainloop()

Answer 1

This is a very surface-level answer, but as much as I can traceback from the code the OpenCv throws this when cv2.cvtColor(img,cv2.COLOR_BGR2GRAY) is called and that points to maybe the image data is empty:

https://docs.opencv.org/3.4/d8/dfe/classcv_1_1VideoCapture.html#a473055e77dd7faa4d26d686226b292c1

Answer 2

If you are working on Windows you have to use \\ it instead of \ Linux . It's a pain in the ass I know, but for some reason Microsoft likes to annoy programmers with little differences like this. You are not the only one who forgets, I learned this the hard way.