Develop Reference

Difference between two images using emgu

I'm coding in C# and I need help with the difference between two images. I'm using the emgu to help me with this part. The problem here is that as long as there is a diff in the pixel, it will be shown in the resulted pic.
However, what I need is if the pixel for the RefImg is higher than the CompImg, the color should be red and if it is lesser it should be green.
The code should take a minimal amount of time to execute too.
The code below is what I'm using now.
Image<Bgr, Byte> RefImg = new Image<Bgr, Byte>(new Bitmap(refImg));
Image<Bgr, Byte> CompImg = new Image<Bgr, Byte>(new Bitmap(compImg));
Image<Bgr, Byte> Difference; //Difference
double Threshold = 5;
Difference = RefImg.AbsDiff(CompImg);
Difference = Difference.ThresholdBinary(new Bgr(Threshold, Threshold, Threshold), new Bgr(0, 255, 0));

Using Abs diff allow you to find différences but not the sign due to absolute value operator.
To find greater and lower pixels value you must use cmp function.
Image<Bgr, Byte> RefImg = new Image<Bgr, Byte>(...);
Image<Bgr, Byte> CompImg = new Image<Bgr, Byte>(...);
//Convert to gray levels or split channels
Image<Gray, Byte> RefImgGray = RefImg.Convert<Gray, byte>();
Image<Gray, Byte> CompImgGray = CompImg.Convert<Gray, byte>();
//Compare image and build mask
Image<Gray, Byte> MaskDifferenceHigh = RefImgGray.Cmp(CompImgGray, CmpType.GreaterThan);
Image<Gray, Byte> MaskDifferenceLow = RefImgGray.Cmp(CompImgGray, CmpType.LessThan);
//Draw result
Image<Bgr, byte> result = RefImg.CopyBlank();
result.SetValue(new Bgr(Color.Red),MaskDifferenceHigh);
result.SetValue(new Bgr(Color.Green), MaskDifferenceLow);
Hope it helps.

Determine most popular Hue of an image with HSV Histogram Emgu CV 3.0.0.2158

Here is the code I am working with currently
Image<Hsv, byte> hsvImage = tempImage.Convert<Hsv, byte>();
Image<Gray, byte>[] channels = hsvImage.Split();
Image<Gray, byte> hue = channels[0];
DenseHistogram hist = new DenseHistogram(255, new RangeF(0, 255));
hist.Calculate<byte>(new Image<Gray, Byte>[] { hue }, true, null);
double[] minV, maxV;
Point[] minL, maxL;
hist.MinMax(out minV, out maxV, out minL, out maxL); //only gets lowest and highest, not most popular
Now I use the maxL[0].Y and I have some ranges set up to find out what color it is, but these arent numbers I can just pull out of the image directly. My question is, is there a way to find the most used color with a histogram or will I have to convert the image to black and white and look for the colors I want?

Detecting Text Regions from image using EmguCV

I am new to EmguCV and OpenCV. I want to detect the text Regions from an Image using EmguCV.
There are already some solutions posted on Stack using OpenCV.
Extracting text OpenCV
But unable to convert that OpenCV code to EmguCV.

Here is a direct conversion of the accepted answer in the link you provided into c# with EMGU. You might have to make some alterations since its a slightly different implementation but it should get you started. I also doubt it is a very robust so depending on your specific use it might not be suitable. Best of luck.
public List<Rectangle> detectLetters(Image<Bgr, Byte> img)
{
List<Rectangle> rects = new List<Rectangle>();
Image<Gray, Single> img_sobel;
Image<Gray, Byte> img_gray, img_threshold;
img_gray = img.Convert<Gray, Byte>();
img_sobel = img_gray.Sobel(1,0,3);
img_threshold = new Image<Gray, byte>(img_sobel.Size);
CvInvoke.cvThreshold(img_sobel.Convert<Gray, Byte>(), img_threshold, 0, 255, Emgu.CV.CvEnum.THRESH.CV_THRESH_OTSU);
StructuringElementEx element = new StructuringElementEx(3, 17, 1, 6, Emgu.CV.CvEnum.CV_ELEMENT_SHAPE.CV_SHAPE_RECT);
CvInvoke.cvMorphologyEx(img_threshold, img_threshold, IntPtr.Zero, element, Emgu.CV.CvEnum.CV_MORPH_OP.CV_MOP_CLOSE, 1);
for (Contour<System.Drawing.Point> contours = img_threshold.FindContours(); contours != null; contours = contours.HNext)
{
if (contours.Area > 100)
{
Contour<System.Drawing.Point> contours_poly = contours.ApproxPoly(3);
rects.Add(new Rectangle(contours_poly.BoundingRectangle.X, contours_poly.BoundingRectangle.Y, contours_poly.BoundingRectangle.Width, contours_poly.BoundingRectangle.Height));
}
}
return rects;
}
Usage:
Image<Bgr, Byte> img = new Image<Bgr, Byte>("VfDfJ.png");
List<Rectangle> rects = detectLetters(img);
for (int i=0;i<rects.Count();i++)
img.Draw(rects.ElementAt<Rectangle>(i),new Bgr(0,255,0),3);
CvInvoke.cvShowImage("Display", img.Ptr);
CvInvoke.cvWaitKey(0);
CvInvoke.cvDestroyWindow("Display");

separating image after watershed using emgu.cv

i have a blood image and i applied watershed on it .. its works and determines the cells but i don't know how to put each cell in a separate image .. i'm working with emgu.cv can i get some help
here i segment the picture using my watershed method and then put the marker on the original image
Image<Gray, Int32> boundaryImage = watershedSegmenter.Process(image);
Image<Gray, Byte> test = watershedSegmenter.GetWatersheds(); Image<Bgr, byte>dest=new Image<Bgr, byte>(image.Width, image.Height);
dest = image.And(image, test);
pictureBox1.Width = boundaryImage.ToBitmap().Width;
pictureBox1.Height = boundaryImage.ToBitmap().Height;
pictureBox1.BackgroundImage = boundaryImage.ToBitmap();

It seems like EMGUcv cvWatershed() is having some bugs which is not yet resolved. The Marker Image is always returning white image. Can you share your 1st stage output images?
I'm not able to view any images by using this code.
Image<Bgr, Byte> image = Img_Source_Bgr.Copy();
Image<Gray, Int32> marker = new Image<Gray, Int32>(image.Width, image.Height);
Rectangle rect = image.ROI;
marker.Draw(
new CircleF(
new PointF(rect.Left + rect.Width / 2.0f, rect.Top + rect.Height / 2.0f),
/*(float)(Math.Min(image.Width, image.Height) / 20.0f)*/ 5.0f),
new Gray(255),
0);
Image<Bgr, Byte> result = image.ConcateHorizontal(marker.Convert<Bgr, byte>());
Image<Gray, Byte> mask = new Image<Gray, byte>(image.Size);
CvInvoke.cvWatershed(image, marker);
CvInvoke.cvCmpS(marker, 0.10, mask, CMP_TYPE.CV_CMP_GT);
imageBox1.Image = mask;

Value range for Image HSV for color extraction EMGUCV

In the following,
Image<Hsv, Byte> hsvimg = img.Convert<Hsv, Byte>();
Image<Gray, Byte>[] channels = hsvimg.Split();
Image<Gray, Byte> imghue = channels[0];
Image<Gray, Byte> imgsat = channels[1];
Image<Gray, Byte> imgval = channels[2];
Image<Gray, byte> huefilter = imghue.InRange(new Gray(?), new Gray(?));
Image<Gray, byte> satfilter = imghue.InRange(new Gray(?), new Gray(?));
Image<Gray, byte> valfilter = imgval.InRange(new Gray(?), new Gray(?));
What is the range value of different channel (h, s, v) for different color extraction? Is it 0-255 or 0-128. I want to detect Orange, Black and Sky blue object for an image.

Can you try something like this for orange
Image<Gray, byte> huefilter =
imghue.InRange(new Gray(Color.Orange.GetHue() - 10),
new Gray(Color.Orange.GetHue() + 10));
-10 and +10 is just a guess and could be broad. just play with it and see what works.
for satfilter you can use Color.Orange.GetSaturation()
and for the third one, I'm assuming you can use Color.Orange.GetBrightness()