python - OpenCV trackbar 断言失败错误

Question

我想用opencv做前景分割。我编写了带有轨迹条的代码，这样我就可以找到最佳的分割参数。执行代码时它会工作，图像显示时带有标记的轮廓等。但是当我尝试在轨迹栏上移动条时。我收到以下错误。

OpenCV(3.4.1) Error: Assertion failed (size.width>0 && size.height>0) in imshow, file /feedstock_root/build_artefacts/opencv_1523502125490/work/opencv-3.4.1/modules/highgui/src/window.cpp, line 356
Traceback (most recent call last):
  File "forgroundsegmentation.py", line 17, in foreground_segment
    cv2.imshow('brightness preprocess', tmp)

这是我的代码。

import cv2
import numpy as np

winName = "ForeGround Segment"

def foreground_segment(src, a=None,b=None, useEqualize=1, blurSize=21, th1=None, brightness=None):
    winName = "ForeGround Segment"
    tmp = brightness

    if (blurSize >= 3):
        blurSize += (1 - blurSize % 2)
        tmp = cv2.GaussianBlur(tmp, (blurSize, blurSize), 0)
    if (useEqualize):
        tmp = cv2.equalizeHist(tmp)

    cv2.imshow('brightness preprocess', tmp)
    #cv2.imwrite('../BrightnessPreprocess.png', tmp)

    ret, tmp = cv2.threshold(tmp, th1, 255, cv2.THRESH_BINARY_INV)
    cv2.imshow(winName, tmp)

    im2, contours, hierarchy = cv2.findContours(tmp, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
    dst = src

    #print(contours)    

    maxDim = 0
    largest = -1
    for i in range(len(contours)):
        cv2.drawContours(dst, contours, largest, (0, 0, 255), 1)
        dim = len(contours[i])
        if (dim > maxDim):
            maxDim = dim
            largest = i

    img_mask = np.zeros(src.shape, np.uint8)

    if (largest >= 0):
        theImg = contours[largest]
        cv2.polylines(dst, theImg, True, (0, 255,0), 2)
        cv2.drawContours(img_mask, contours, largest, 255, -1)

    cv2.imshow("Result Mask", img_mask)
    cv2.imshow("Result Contour", dst)
    #cv2.imwrite("../img_mask.png", img_mask)
    #cv2.imwrite("../result.png", dst)

if __name__ == '__main__':
    src = cv2.imread('frontal.png')
    print(src.shape)
    src = cv2.resize(src, (int(src.shape[0]/3), int(src.shape[1]/3)), interpolation = cv2.INTER_AREA)
    #src = cv2.resize(src, (500, 500), interpolation = cv2.INTER_AREA)
    cv2.imshow(winName, src)
    dst = cv2.cvtColor(src, cv2.COLOR_BGR2HSV)
    hsv_planes = cv2.split(dst)
    brightness = hsv_planes[2]
    useEqualize = 1
    blurSize = 21
    th1 = int(33.0 * 255 / 100)
    cv2.createTrackbar("Equalize", winName, useEqualize, 1, foreground_segment)
    cv2.createTrackbar("Blur Sigma", winName, blurSize, 100, foreground_segment)
    cv2.createTrackbar("Threshold", winName, th1, 255, foreground_segment)

    foreground_segment(src ,0, 0, useEqualize, blurSize, th1, brightness=brightness)
    cv2.waitKey(0)
    cv2.destroyAllWindows   

我认为我做的一切都是正确的。有人可以指出我哪里出错了。

Answer 1

首先，构建这种类型的分割工具是个好主意!

您提供的代码仅使用 cv2.createTrackbar() 创建轨迹栏。为了使用它们，您需要实现 cv2.getTrackbarPos() 以在滑动轨迹栏时获取不同的值。

我修改了相同的代码:

import cv2
import numpy as np

winName = "ForeGround Segment"

def foreground_segment(im, brightness, useEqualize=1, blurSize=21, th1=None):
    winName = "ForeGround Segment"
    tmp = brightness

    if (blurSize >= 3):
        blurSize += (1 - blurSize % 2)
        tmp = cv2.GaussianBlur(tmp, (blurSize, blurSize), 0)
    if (useEqualize):
        tmp = cv2.equalizeHist(tmp)

    cv2.imshow('brightness preprocess', tmp)
    #cv2.imwrite('../BrightnessPreprocess.png', tmp)

    ret, tmp = cv2.threshold(tmp, th1, 255, cv2.THRESH_BINARY_INV)
    cv2.imshow('threshold', tmp)

    im2, contours, hierarchy = cv2.findContours(tmp, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
    dst = im.copy()

    #print(contours)    

    maxDim = 0
    largest = -1
    for i in range(len(contours)):
        cv2.drawContours(dst, contours, largest, (0, 0, 255), 1)
        dim = len(contours[i])
        if (dim > maxDim):
            maxDim = dim
            largest = i

    img_mask = np.zeros(src.shape, np.uint8)

    if (largest >= 0):
        theImg = contours[largest]
        cv2.polylines(dst, theImg, True, (0, 255,0), 2)
        cv2.drawContours(img_mask, contours, largest, 255, -1)

    cv2.imshow("Result Mask", img_mask)
    cv2.imshow("Result Contour", dst)
    #cv2.imwrite("../img_mask.png", img_mask)
    #cv2.imwrite("../result.png", dst)

if __name__ == '__main__':
    src = cv2.imread('frontal.png')
    src = cv2.resize(src, (int(src.shape[0]/3), int(src.shape[1]/3)), interpolation = cv2.INTER_AREA)
    cv2.imshow(winName, src)
    dst = cv2.cvtColor(src, cv2.COLOR_BGR2HSV)
    hsv_planes = cv2.split(dst)
    brightness = hsv_planes[2]
    useEqualize = 1
    blurSize = 21
    th1 = int(33.0 * 255 / 100)
    cv2.createTrackbar("Equalize", winName, useEqualize, 1, foreground_segment)
    cv2.createTrackbar("Blur Sigma", winName, blurSize, 100, foreground_segment)
    cv2.createTrackbar("Threshold", winName, th1, 255, foreground_segment)

    while(1):

        #--- Using cv2.getTrackbarPos() to get values from the slider ---
        useEqualize = cv2.getTrackbarPos('Equalize', winName)
        blurSize = cv2.getTrackbarPos('Blur Sigma', winName)
        th1 = cv2.getTrackbarPos('Threshold', winName)

        foreground_segment(src, brightness, useEqualize, blurSize, th1)

        #--- Press Q to quit ---            
        k = cv2.waitKey(1) & 0xFF
        if k == 27:
            break

    cv2.destroyAllWindows()