DearPyGUIとOpenCVのテスト。中央付近の平均値をプロットするようにした。

dearpygui_opencv.py

import dearpygui.dearpygui as dpg
import array
import cv2
import numpy as np

image_width = 320
image_height = 180
average_rect = (60,120,120,200) # y0,y1,x0,x1

def update_image(img):
    img = cv2.cvtColor(img,cv2.COLOR_BGR2RGBA)
    img = img.astype(np.float32)/255.0
    dpg.set_value("image_tag", img.flatten())

dmax=500
data_x=np.linspace(0,dmax-1,dmax)
data_r=np.zeros(dmax)
data_g=np.zeros(dmax)
data_b=np.zeros(dmax)


def push_data(data, newdata):
    global dmax
    data[:dmax-1] =data[1:dmax] 
    data[dmax-1]=newdata
    return data

def update_plot(img):
    global data_x,data_r
    roi=img[average_rect[0]:average_rect[1],average_rect[2]:average_rect[3],:]
    # img is opencv BGR image
    b=roi[:,:,0]
    g=roi[:,:,1]
    r=roi[:,:,2]
    push_data(data_r, np.average(r))
    push_data(data_g, np.average(g))
    push_data(data_b, np.average(b))

    dpg.set_value('plot_r_tag', [data_x, data_r])
    dpg.set_value('plot_g_tag', [data_x, data_g])
    dpg.set_value('plot_b_tag', [data_x, data_b])

def setup():
    dpg.create_context()

    img = np.zeros( (image_height,image_width,4), dtype=np.float32)
    with dpg.texture_registry(show=False):
        h,w,c = img.shape
        dpg.add_raw_texture(w,h, img, format=dpg.mvFormat_Float_rgba, tag="image_tag")

    with dpg.window(label="Image", no_resize=True,pos=(20,0)):
        dpg.add_image("image_tag")

    with dpg.window(label="Statistics", no_resize=True,pos=(20,200)):
        with dpg.plot( height=160, width=320):
            dpg.add_plot_legend()
            dpg.add_plot_axis(dpg.mvXAxis, label="")
            dpg.set_axis_ticks(dpg.last_item(),())
            dpg.add_plot_axis(dpg.mvYAxis, label="average", tag="y_axis")
            dpg.set_axis_limits("y_axis", 0, 255)
            dpg.add_line_series(data_x, data_b, label="B",  parent="y_axis", tag="plot_b_tag")
            dpg.add_line_series(data_x, data_r, label="R", parent="y_axis", tag="plot_r_tag")
            dpg.add_line_series(data_x, data_g, label="G",  parent="y_axis", tag="plot_g_tag")

    dpg.create_viewport(title='OpenCV and DearPyGui', width=400, height=400,resizable=False)
    dpg.setup_dearpygui()
    dpg.show_viewport()

def main():
    setup()
    capture = cv2.VideoCapture(1)
    while dpg.is_dearpygui_running():
        ret, img = capture.read()
        if(ret):
            img = cv2.resize(img,(image_width,image_height))
            update_plot(img)
            img = cv2.rectangle(img,(average_rect[2],average_rect[0]),(average_rect[3],average_rect[1]),(0,0,255),2)
            update_image(img)
        dpg.render_dearpygui_frame()
    dpg.destroy_context()

if __name__ == '__main__':
    main()

動作例。
https://user-images.githubusercontent.com/5352510/147673830-31c29dd6-6702-4c5d-8bae-34f1ee0ab74b.mp4
グラフがぬるぬるで大変よい。