PySimpleGUI drawimage not displaying image - image

Question

I have an RGB image, which I immediately take the red component. I then convert the resulting grayscale into bytes and display it in Graph using draw_image. However, only the background is shown and the red component image is not displayed. Let img be my RGB image. Here is my code:
import cv2
import PySimpleGUI as sg
from PIL import Image, ImageTk
r,g,b = cv2.split(img)
data = bytes(Image.fromarray(r).tobytes())
width = len(b)
length = len(b[0])
layout = [[sg.Graph(
canvas_size=(length, width),
graph_bottom_left=(0, 0),
graph_top_right=(length, width),
key="-GRAPH-",
change_submits=True,
background_color='black',
drag_submits=True) ]]
window = sg.Window(layout, finalize=True)
window.Maximize()
graph = window["-GRAPH-"]
graph.draw_image(data = data, location=(0,width))
while True:
event, values = window.read()
if event == sg.WIN_CLOSED:
break
The result is nothing but black background. I have checked that the image img and the red component r are both correct (i.e. statements like imshow will give the right image). The problem therefore lies in either the line data = bytes(Image.fromarray(r).tobytes()) or graph.draw_image(data = data, location=(0,width)). However, both seem correct to me. What am I missing? Is there any workarounds? As a side note, I am not allowed to save any images.

Answer 1

Image.tobytes(encoder_name='raw', *args)
This method returns the raw image data from the internal storage. For compressed image data (e.g. PNG, JPEG) use save(), with a BytesIO parameter for in-memory data.
import io
import cv2
import PySimpleGUI as sg
from PIL import Image, ImageTk
img = cv2.imread('D:/images.jpg')
r,g,b = cv2.split(img)
im = Image.fromarray(r)
width, height = im.size
buffer = io.BytesIO()
im.save(buffer, format='PNG')
data = buffer.getvalue()
layout = [[sg.Graph(
canvas_size=(width, height),
graph_bottom_left=(0, 0),
graph_top_right=(width, height),
key="-GRAPH-",
change_submits=True,
background_color='black',
drag_submits=True) ]]
window = sg.Window('Title', layout, finalize=True)
# window.Maximize()
graph = window["-GRAPH-"]
graph.draw_image(data = data, location=(0, height))
while True:
event, values = window.read()
if event == sg.WIN_CLOSED:
break
window.close()