我在使用openCv裁剪IplImage时遇到了问题。假设tmp和img都是IplImage*，使用以下代码：
printf("Orig dimensions: %dx%d\n", img->width, img->height);
cvSetImageROI(img, cvRect(0, 0,500,500));
tmp = cvCreateImage(cvGetSize(img),img->depth,img->nChannels);
cvCopy(img, tmp, NULL);
cvResetImageROI(img);
img = cvCloneImage(tmp);
printf("Orig dimensions after crop: %dx%d\n", tmp->width, tmp->height);
当我使用上面的cvRect时，我将得到一个按预期裁剪为500 x 500大小的图像；然而，当我使用矩形（400，400，500，500）时，我将得到一个大小为500 x 320的图像。
cvRect 被定义为 (int x, int y, int width, int height)，而不是 (int left, int top, int right, int bottom)。因此，您选择了一个从点 (x,y) = (400,400) 开始的 500x500 区域。我猜测您的图像高度为 720 ;)
使用OpenCV进行图像裁剪
Mat image=imread("image.png",1);
int startX=200,startY=200,width=100,height=100
Mat ROI(image, Rect(startX,startY,width,height));
Mat croppedImage;
// Copy the data into new matrix
ROI.copyTo(croppedImage);
imwrite("newImage.png",croppedImage);
IplImage *source_image;
IplImage *cropped_Image1;
cout << "Width:" << source_image->width << " pixels" << endl;
cout << "Height:" << source_image->height << " pixels" << endl;
int width = source_image->width;
int lenght = source_image->height;
cv::Rect roi;
roi.x = 1200; //1200 // 950
roi.y = 355; //350 //150
roi.width = 2340; //2360 //2750
roi.height = 1425; //1235 /2500 //2810 //2465 fully braille sheet
cropped_Image1 = cvCreateImage(cvSize(roi.width, roi.height), source_image->depth, source_image->nChannels);
cvSetImageROI(source_image, roi);
cvCopy(source_image, cropped_Image1);
cvResetImageROI(source_image);
cvShowImage("Cropped Image", cropped_Image1);
cvSaveImage("1_cropped.jpg", cropped_Image1);
你可以轻松地使用Python裁剪图像
roi = oriImage[refPoint[0][1]:refPoint[1][1], refPoint[0][0]:refPoint[1][0]]
cv2.setMouseCallback("image", mouse_crop)函数。该函数大致如下：
def mouse_crop(event, x, y, flags, param):
# grab references to the global variables
global x_start, y_start, x_end, y_end, cropping
# if the left mouse button was DOWN, start RECORDING
# (x, y) coordinates and indicate that cropping is being
if event == cv2.EVENT_LBUTTONDOWN:
x_start, y_start, x_end, y_end = x, y, x, y
cropping = True
# Mouse is Moving
elif event == cv2.EVENT_MOUSEMOVE:
if cropping == True:
x_end, y_end = x, y
# if the left mouse button was released
elif event == cv2.EVENT_LBUTTONUP:
# record the ending (x, y) coordinates
x_end, y_end = x, y
cropping = False # cropping is finished
refPoint = [(x_start, y_start), (x_end, y_end)]
if len(refPoint) == 2: #when two points were found
roi = oriImage[refPoint[0][1]:refPoint[1][1], refPoint[0][0]:refPoint[1][0]]
cv2.imshow("Cropped", roi)
cv2.imwrite("crop.jpg",roi)
您可以从这里获取详细信息：使用Python进行鼠标点击和裁剪
对于C++，您可以按照以下方式操作：
void mouse_call(int event,int x,int y,int,void*)
{
if(event==EVENT_LBUTTONDOWN)
{
leftDown=true;
cor1.x=x;
cor1.y=y;
cout <<"Corner 1: "<<cor1<<endl;
}
if(event==EVENT_LBUTTONUP)
{
if(abs(x-cor1.x)>20&&abs(y-cor1.y)>20) //checking whether the region is too small
{
leftup=true;
cor2.x=x;
cor2.y=y;
cout<<"Corner 2: "<<cor2<<endl;
}
else
{
cout<<"Select a region more than 20 pixels"<<endl;
}
}
if(leftDown==true&&leftup==false) //when the left button is down
{
Point pt;
pt.x=x;
pt.y=y;
Mat temp_img=img.clone();
rectangle(temp_img,cor1,pt,Scalar(0,0,255)); //drawing a rectangle continuously
imshow("Original",temp_img);
}
if(leftDown==true&&leftup==true) //when the selection is done
{
box.width=abs(cor1.x-cor2.x);
box.height=abs(cor1.y-cor2.y);
box.x=min(cor1.x,cor2.x);
box.y=min(cor1.y,cor2.y);
Mat crop(img,box); //Selecting a ROI(region of interest) from the original pic
namedWindow("Cropped Image");
imshow("Cropped Image",crop); //showing the cropped image
leftDown=false;
leftup=false;
}
}