场景是这样的，我有一个图像，我只想从中提取文本以进行进一步的 OCR 处理，我试图通过腐蚀和膨胀来删除徽标，但是当卡片的背景中有图像或卡片是时它失败了分成2种不同的颜色，所以我想计算卡片的直方图，然后过滤文本，因为它将在背景或任何其他非文本区域中具有最小的峰值我得到这个opencv代码来计算图像的直方图
OpenCV 代码：
IplImage* trueColorImage = cvLoadImage("plastics.jpg");
TrueColorIplImg=[self CreateIplImageFromUIImage:trueColorImage];
IplImage* channel = cvCreateImage( cvGetSize(TrueColorIplImg), 8, 1);
IplImage *hist_img = cvCreateImage(cvSize(300,240), 8, 1);
cvSet( hist_img, cvScalarAll(255), 0 );
CvHistogram *hist_red;
CvHistogram *hist_green;
CvHistogram *hist_blue;
int hist_size = 256;
float range[]={0,256};
float* ranges[] = { range };
float max_value = 0.0;
float max = 0.0;
float w_scale = 0.0;
hist_red = cvCreateHist(1, &hist_size, CV_HIST_ARRAY, ranges, 1);
hist_green = cvCreateHist(1, &hist_size, CV_HIST_ARRAY, ranges, 1);
hist_blue = cvCreateHist(1, &hist_size, CV_HIST_ARRAY, ranges, 1);
cvSetImageCOI(TrueColorIplImg,3);
cvCopy(TrueColorIplImg,channel);
cvResetImageROI(TrueColorIplImg);
cvCalcHist( &channel, hist_red, 0, NULL );
cvSetImageCOI(TrueColorIplImg,2);
cvCopy(TrueColorIplImg,channel);
cvResetImageROI(TrueColorIplImg);
cvCalcHist( &channel, hist_green, 0, NULL );
cvSetImageCOI(TrueColorIplImg,1);
cvCopy(TrueColorIplImg,channel);
cvResetImageROI(TrueColorIplImg);
cvCalcHist( &channel, hist_blue, 0, NULL );
cvGetMinMaxHistValue( hist_red, 0, &max_value, 0, 0 );
cvGetMinMaxHistValue( hist_green, 0, &max, 0, 0 );
max_value = (max > max_value) ? max : max_value;
cvGetMinMaxHistValue( hist_blue, 0, &max, 0, 0 );
max_value = (max > max_value) ? max : max_value;
cvScale( hist_red->bins, hist_red->bins, ((float)hist_img->height)/max_value, 0 );
cvScale( hist_green->bins, hist_green->bins, ((float)hist_img->height)/max_value, 0 );
cvScale( hist_blue->bins, hist_blue->bins, ((float)hist_img->height)/max_value, 0 );
printf("Scale: %4.2f pixels per 100 units\n", max_value*100/((float)hist_img->height));
w_scale = ((float)hist_img->width)/hist_size;
for( int i = 0; i < hist_size; i++ )
{
cvRectangle( hist_img, cvPoint((int)i*w_scale , hist_img->height),
cvPoint((int)(i+1)*w_scale, hist_img->height - cvRound(cvGetReal1D(hist_red->bins,i))),
CV_RGB(255,0,0), -1, 8, 0 );
cvRectangle( hist_img, cvPoint((int)i*w_scale , hist_img->height),
cvPoint((int)(i+1)*w_scale, hist_img->height - cvRound(cvGetReal1D(hist_green->bins,i))),
CV_RGB(0,255,0), -1, 8, 0 );
cvRectangle( hist_img, cvPoint((int)i*w_scale , hist_img->height),
cvPoint((int)(i+1)*w_scale, hist_img->height - cvRound(cvGetReal1D(hist_blue->bins,i))),
CV_RGB(0,0,255), -1, 8, 0 );
}