I'm using emgu cv 3.0.0 and I would like to capture frames from a USB cam.
Unfortunately, I get an error while calling Image<Bgr, Byte> image = capture.QueryFrame();
It says, I can't convert from Emgu.CV.Mat to Emgu.CV.Image.
Try this line of code
Image<Bgr, Byte> image = capture.QueryFrame().ToImage<Bgr,Byte>();
In cv v 3.0.0 most methods use Mat for image representation.
You can try this to get the frame from the camera:
Mat frame = new Mat();
_capture.Retrieve(frame, 0);
For conversion to gray:
Mat grayFrame = new Mat();
CvInvoke.CvtColor(frame, grayFrame, ColorConversion.Bgr2Gray);
Also you can see how it works in examples here.
Related
I want to copy an image from camera to anothe imagebox using ROI. I have searched a lot references about ROI but it still doesn't work. Anybody can help me, please ?
These are what I have done
Image<Bgr, Byte> sourceImage1 = CaptureCam1.QueryFrame();
SourceImageBox.Image = sourceImage1;
ImageCopy = new Image<Bgr, Byte>(Template_Box.Width, Template_Box.Height);
sourceImage1.ROI = new Rectangle(SourceImageBox.Location.X, SourceImageBox.Location.Y, SourceImageBox.Width, SourceImageBox.Height);
sourceImage1.CopyTo(ImageCopy);
Template_Box.Image = ImageCopy;
You should use it like below:
sourceImage1.ROI = new Rectangle(SourceImageBox.Location.X, SourceImageBox.Location.Y, SourceImageBox.Width, SourceImageBox.Height);
Template_Box.Image = sourceImage1.clone();
I'm creating an application of watermarking using opencv, I'm not able to set background of image as transparent.
I'm using this code Scalar colorScalar = new Scalar(255,255,255,0);
Can any body help me how to make background transparent. I'm using PNG format image.
targetMat = new Mat(targetSize, scaledImage.type(), colorScalar);
Mat waterSubmat = targetMat.submat((int)offsetY,scaledImage.height(), (int)offsetX, scaledImage.width());
scaledImage.copyTo(waterSubmat);
center = new org.opencv.core.Point(pivotX, pivotY);
Mat rotImage = Imgproc.getRotationMatrix2D(center, degreevaluechange, 1);
Mat resultMat = new Mat(2,3, CvType.CV_32FC1);
colorScalar = new Scalar(255,255,255,0);
Imgproc.warpAffine(targetMat, resultMat, rotImage, targetSize, Imgproc.INTER_AREA, Imgproc.BORDER_CONSTANT, colorScalar);
scaledImage = resultMat.clone();
If you want to load your PNG image with the alpha channel and therefore load your image with transparenty, you have to use this code:
imread("image.png",-1)
You can find more informations in the opencv documentation here:
http://docs.opencv.org/modules/highgui/doc/reading_and_writing_images_and_video.html?highlight=imread#imread
As you see in the documentation provided by Maximus. You need to create a 4 channel Mat:
Mat* targetMat = new Mat(targetSize, CV_8UC4, colorScalar);
vector<int> compression_params;
compression_params.push_back(CV_IMWRITE_PNG_COMPRESSION);
compression_params.push_back(9);
try {
imwrite("alpha.png", targetMat, compression_params);
}
catch (runtime_error& ex) {
fprintf(stderr, "Exception converting image to PNG format: %s\n", ex.what());
return 1;
}
Then add the parameters and write. (This code is from the documentation)
I am new to EMGU.CV and I am struggling a bit. Let me start by giving some background of the project, i am trying to track a users fingers, i.e. calculate the users finger tips, but i am struggling a bit. I have created a set of code which filters the depth information to only a certain range and I generate a Bitmap image, tempBitmap, i then convert this image to a greyscale image using EMGU.CV which can be used by cvCanny. Once this is done i apply dilate filter to the canny image to thicken up the outline of the hand to better improve the chance of generating a successful contour, I then try to get the contours of the hand. Now what i have managed to do is to draw a box around the hand, but i am struggling to find a way to convert the contours generated by FindContours to a set of Points i can use to draw the contour with. the variable depthImage2 is a Bitmap image variable i use to draw on before assinging it to the picturebox variable on my C# form based application. any information or guidance you can provide me with will be greatly appreciated, also if my code isnt correct maybe guiding me in a direction where i can calculate the finger tips. I think i am almost there i am just missing something, so any help of any kind will be appreciated.
Image<Bgr, Byte> currentFrame = new Image<Bgr, Byte>(tempBitmap);
Image<Gray, Byte> grayImage = currentFrame.Convert<Gray, Byte>().PyrDown().PyrUp();
Image<Gray, Byte> cannyImage = new Image<Gray, Byte>(grayImage.Size);
CvInvoke.cvCanny(grayImage, cannyImage, 10, 60, 3);
StructuringElementEx kernel = new StructuringElementEx(
3, 3, 1, 1, Emgu.CV.CvEnum.CV_ELEMENT_SHAPE.CV_SHAPE_ELLIPSE);
CvInvoke.cvDilate(cannyImage, cannyImage, kernel, 1);
IntPtr cont = IntPtr.Zero;
Graphics graphicsBitmap = Graphics.FromImage(depthImage2);
using (MemStorage storage = new MemStorage()) //allocate storage for contour approximation
for (Contour<Point> contours =
cannyImage.FindContours(Emgu.CV.CvEnum.CHAIN_APPROX_METHOD.CV_CHAIN_APPROX_SIMPLE,
Emgu.CV.CvEnum.RETR_TYPE.CV_RETR_EXTERNAL);
contours != null; contours = contours.HNext)
{
IntPtr seq = CvInvoke.cvConvexHull2(contours, storage.Ptr, Emgu.CV.CvEnum.ORIENTATION.CV_CLOCKWISE, 0);
IntPtr defects = CvInvoke.cvConvexityDefects(contours, seq, storage);
Seq<Point> tr = contours.GetConvexHull(Emgu.CV.CvEnum.ORIENTATION.CV_CLOCKWISE);
Seq<Emgu.CV.Structure.MCvConvexityDefect> te = contours.GetConvexityDefacts(
storage, Emgu.CV.CvEnum.ORIENTATION.CV_CLOCKWISE);
graphicsBitmap.DrawRectangle(
new Pen(new SolidBrush(Color.Red)), tr.BoundingRectangle);
}
Contour contours = cannyImage.FindContours(Emgu.CV.CvEnum.CHAIN_APPROX_METHOD.CV_CHAIN_APPROX_NONE) //to return all points
then:
List<Point[]> convertedContours = new List<Point[]>();
while(cotours!=null)
{
var contourPoints = contours.ToArray(); //put Seq<Point> to Point[], ToList() is also available ?
convertedContours.Add(contourpoints);
contours = contours.HNext;
}
you can draw contour by image Draw functon overload.
just find signature that contains parameter Seq<>
....
So, I have this image of a face:
http://i.stack.imgur.com/gsZnh.jpg
and I need to be able to determine the most dominate/prominent RGB and The YCrCB value from it using Emgu CV. Thank you for the help.
You should first get the histogram of every color channel. Then you can use minmax function to get the most dominant color.
The code I'm posting is for an HSV image, you can change channel names for your color space.
Image<Gray, Byte>[] channels = hsv1.Split();
Image<Gray, Byte> ImgHue = channels[0];
Image<Gray, Byte> ImgSat = channels[1];
Image<Gray, Byte> ImgVal = channels[2];
DenseHistogram histo1 = new DenseHistogram(255, new RangeF(0, 255));
histo1.Calculate<byte>(new Image<Gray, byte>[] { ImgHue }, true, null);
float minV, maxV;
int[] minL;
int[] maxL;
histo1.MinMax(out minV, out maxV, out minL, out maxL);
string mystr = Convert.ToString(maxL[0]);
label1.Text = "Hue= " + mystr;
You can do the same thing for Saturation and Value channels too.
You can use histogram to find the distribution of colors and choose the highest value as the dominant color. Don't know about related functions in Emgu CV though for now. Good Luck
how to convert a Bgr image to YCbCr in EmguCV ?
Probably you could use the method img.Convert();
one does not simply Convert a BGR Image into YCbCr...
Image<Bgr, byte> BGR;
Image<Ycc, Byte> YCrCbFrame = BGR.Convert<Ycc, Byte>();