0

我正在使用 OpenCV 在 VS 2010 中开发一个程序。我想测量计算机相机捕获的每一帧的亮度。但是，相机的软件会在 2-3 帧后稳定亮度。例如，如果我将拇指放在相机前面，则第一帧的亮度为 2（范围从 0 到 255），但是当我的拇指保持在相机前面时，亮度变为 7 和 20 - 它在那里稳定下一帧。所以相机试图让太暗的照片更亮，太亮的照片更暗。

如何在没有相机干扰的情况下测量实际亮度？我的代码是：

#ifdef _CH_
#pragma package <opencv>
#endif
#include "stdafx.h"
#include <highgui.h>

#include "cv.h"
#include <stdio.h>
#include <stdlib.h>
#include "..\utilities.h"

int _tmain(int argc, _TCHAR* argv[])
{
FILE *file;
IplImage *img;
IplImage* grayscale_image;
int c, i, j, Luminance = 0, Pixel_Num = 0;
int Avg_Luminance;
int width_step;
int pixel_step;
// allocate memory for an image

// capture from video device #1
CvCapture* capture;
// create a window to display the images
cvNamedWindow("mainWin", CV_WINDOW_AUTOSIZE);
// position the window
cvMoveWindow("mainWin", 5, 5);
while(1)
{
    if(file = fopen("luminance_value.txt", "w+"))
    {
        // retrieve the captured frame
        capture= cvCaptureFromCAM(1);
        img=cvQueryFrame(capture);

        grayscale_image = cvCreateImage( cvGetSize(img), 8, 1 );
        cvConvertImage( img, grayscale_image );
        width_step= grayscale_image->widthStep;
        pixel_step= grayscale_image->widthStep/grayscale_image->width;
        Pixel_Num = grayscale_image->width * grayscale_image->height;
        for(i = 0; i < grayscale_image->height; i++)
        {
            for(j = 0; j < grayscale_image->width; j++)
            {
                unsigned char* point = GETPIXELPTRMACRO( grayscale_image, j, i, width_step, pixel_step);
                Luminance += point[0];
            }
        }
        Avg_Luminance = Luminance / Pixel_Num;
        //Avg_Luminance = cvGetCaptureProperty(capture,CV_CAP_PROP_BRIGHTNESS);
        //file = fopen("luminance_value.txt", "w+");
        fprintf(file, "%d", Avg_Luminance);
        fclose(file);
        printf("Avg_Luminance = %d\n", Avg_Luminance);
        Luminance = 0;
        Pixel_Num = 0;
        // show the image in the window
        cvShowImage("mainWin", grayscale_image );
        cvReleaseCapture(&capture);
        // wait 10 ms for a key to be pressed
        c=cvWaitKey(10000);
        // escape key terminates program
        if(c == 27)
        break;
    }
    else
    {
        continue;
    }

    }
 return 0;
}
4

0 回答 0