为什么在插入 sqlite3 后在 tkinter window 上显示图片时出现该错误？

Question

我创建了一个 tkinter 来显示来自 PC 的图片，然后插入到 sqlite3 文件中，我的问题是在尝试显示图片时出现错误“无法识别图像文件 <_io.BytesIO object at 0x05B60F28>”从 sqlite 插入后，这是我的代码示例：

def createWidgets(self):
    notebook = ttk.Notebook(root)
    self.Tab_Control1 = Frame(notebook)
    self.Tab_Control2 = Frame(notebook)
    notebook.add(self.Tab_Control1, text="Enter")
    notebook.add(self.Tab_Control2, text="Show")
    notebook.pack(fill='both', expand=1)
    notebook.select(self.Tab_Control1)

    def Insert():
        global img
        global folder_path
        folder_path = StringVar()
        filename = filedialog.askopenfilename(initialdir="/", title="Select An Image", filetypes=(("jpeg files", "*.jpg"), ("gif files", "*.gif*"), ("png files", "*.png")))
        folder_path.set(filename)
        try:
            print(filename)
            if not filename == '':
                self.Tab_Control2.destroy()
                self.Tab_Control2 = Frame(notebook)
                notebook.add(self.Tab_Control2, text="Show")
                notebook.pack(fill='both', expand=1)
                notebook.select(self.Tab_Control2)
                img = np.array(ImageTk.PhotoImage(Image.open(filename)))
                panel = Label(self.Tab_Control2)
                panel.config (image=img)
                panel.pack(side="bottom", fill="both", expand="yes")
                ASK = messagebox.askquestion("HR", "Are you wanting to insert picture into your database ?", icon='warning')
                if ASK == 'yes':
                    conn = sqlite3.connect('datastorage.db')
                    c = conn.cursor()
                    img_str = cv2.imread(filename)
                    c.executescript('drop table if exists Structure1;')
                    c.execute("create table if not exists Structure1 (img blob)")
                    c.execute("insert into Structure1 values (?)", (img_str,))
                    conn.commit()
                    conn.close()
                    messagebox.showinfo("HR", "Done")
        except:
            messagebox.showinfo("HR", "Error, try again")

    def Display():
        global img
        notebook.select(self.Tab_Control2)
        conn = sqlite3.connect('datastorage.db')
        c = conn.cursor()
        filename = "SELECT * from Structure1"
        c.execute(filename)
        record = c.fetchall()
        for row in record:
            print(row)
            photo=row[0]
            fp = io.BytesIO(photo)
            image = Image.open(fp)
            img = ImageTk.PhotoImage(image)
            panel = Label(self.Tab_Control2, image=img)
            panel.image = img
            panel.pack(side="bottom", fill="both", expand="yes")
        conn.commit()
        conn.close()

    self.insert = Button(self.Tab_Control1, font='Helvetica 14 bold', width=15, text="Insert picture", fg='red', bg='light goldenrod yellow', command=Insert)
    self.insert.pack()
    self.display = Button(self.Tab_Control1, font='Helvetica 14 bold', width=15, text="Display picture", fg='red', bg='light goldenrod yellow', command=Display)
    self.display.pack()

Answer 1

您应该使用二进制文件读取而不是 cv2.imread():

...
#img_str = cv2.imread(filename)
with open(filename, "rb") as f:
    img_str = f.read()
c.execute("INSERT INTO Structure1 VALUES (?)", (img_str,))
...

为什么在插入 sqlite3 后在 tkinter window 上显示图片时出现该错误？

why I get that error when displaying picture on tkinter window after inserting into sqlite3?

sqlite

io

numpy

tkinter

python-3.x