Hi i tried compute disparity map using EmguCV, but there must be some bug when i try use StereoBM class, always when i call function FindStereoCorrespondence i will receive this error:
System.AccessViolationException: Attempted to read or write protected memory.
My code is simple:
private Image<Gray, byte> Computer3DPointsFromStereoPair0(Image<Gray, byte> left, Image<Gray, byte> right)
{
Size size = left.Size;
Image<Gray, short> disparityMap = new Image<Gray, short>(size);
using (StereoBM stereoSolver = new StereoBM(Emgu.CV.CvEnum.STEREO_BM_TYPE.BASIC, 0)){
stereoSolver.FindStereoCorrespondence(left, right, disparityMap);
}
return disparityMap.Convert<Gray, byte>();
}
I think it can be somewere in OpenCV dll's...
Please if somebody know how to slove that problem!
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 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.
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<>
....
I am trying to script a greyscale object in a captured image as a matrix of 0 1 that represents a block of object pixels (or something like object style scaling), i can imagine the manual processing by looping the object, scaling and writing the matrix according to the grade of color,
however i'm looking for intelligent or open source tools,
.NET are preferred,
[Update, to explain in more details]
The original images are colored, however, i'm converting it into 256 greyscale, then i want to scale it into black or white only, so at the end of the day it's just a black and white picture i want convert it to zero-one matrix,
the following url contains a discussion of how to convert black-white picture to zero-one matrix using a software called imagemagick:
http://studio.imagemagick.org/discourse-server/viewtopic.php?f=1&t=18433
notice the Zero one matrix which demonstrate a dragon face image!, is there any techniques or open source tools that helping me to achieve that?
Something like the following using Emgu OpenCV for .NET would work.
using Emgu.CV;
using Emgu.CV.CvEnum;
using Emgu.CV.Structure;
using System;
using System.Drawing;
using System.IO;
using (Image<Bgr, Byte> img = new Image<Bgr, Byte>("MyImage.jpg"))
{
Matrix<Int32> matrix = new Matrix<Int32>(img.Width, img.Height);
for (int i = 0; i<img.Height;i++)
{
for (int j = 0; j<img.Width;j++)
{
if (img.Data[i,j,2] == 255 &&
img.Data[i,j,1] == 255 &&
img.Data[i,j,0] == 255)
{
matrix.Data[i,j] = 0;
}
else
{
matrix.Data[i,j] = 1;
}
}
}
TextWriter tw = new StreamWriter("output.txt");
for (int i = 0; i<img.Height;i++)
{
for (int j = 0; j<img.Width;j++)
{
tw.Write(matrix.Data[i,j]);
}
tw.Write(tw.NewLine);
}
}
Note that the snippet above loads colour images and creates a matrix with white as 0 and 1 otherwise.
In order to load and work with grayscale images
the Image<Bgr, Byte> becomes an Image<Gray, Byte> and the comparison simplifies to just
if (img.Data[i,j,0] == 255).
Also to do the thresholding (conversion from colour to grayscale to black and white), you can use Otsu's thresholding using the cvThreshold method, using something like :
int threshold = 150;
Image<Bgr, Byte> img = new Image<Bgr, Byte>("MyImage.jpg");
Image<Gray, Single> img2 = img1.Convert<Gray, Single>();
Image<Gray, Single> img3 = new Image<Gray, Single>(img2.Width, img2.Height);
CvInvoke.cvThreshold(img2, img3, threshold, 255, THRESH.CV_THRESH_OTSU);
Other possible tools include
convert from ImageMagick and pnmoraw from netpbm, as mentioned in the URL you linked, with example snippet convert lib/dragon_face.xbm pbm: | pnmnoraw.
Using PIL (Python Image Library) to iterate through image data and the Python IO functions to write the output data
Using System.Drawing.Bitmap specifically the GetPixel method to iterate through the image data, and C# IO functions to write the output data.
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