Reputation: 11
I'm working on veins detection from image using emgu CV and I have few questions. Is there any simple way to detect color or range of colors? Is there a simple way to replace this color with another (e.g. average color of the image)? How can I achive that without degrading the performance?
Thanks in advance!
Upvotes: 1
Views: 13533
Reputation: 111
I can't imagine this problem has published about 3 years...
public static Image<Bgr, byte> BackgroundToGreen(Image<Bgr, byte> rgbimage)
{
Image<Bgr, byte> ret = rgbimage;
var image = rgbimage.InRange(new Bgr(190, 190, 190), new Bgr(255, 255, 255));
var mat = rgbimage.Mat;
mat.SetTo(new MCvScalar(200, 237, 204), image);
mat.CopyTo(ret);
return ret;
}
Why Matrix?
http://www.emgu.com/wiki/index.php/Working_with_Images#Accessing_the_pixels_from_Mat
Unlike the Image<,> class, where memory are pre-allocated and fixed, the memory of Mat can be automatically re-allocated by Open CV function calls. We cannot pre-allocate managed memory and assume the same memory are used through the life time of the Mat object. As a result, Mat class do not contains a Data property like the Image<,> class, where the pixels can be access through a managed array.
What is InRange?
http://www.emgu.com/wiki/files/2.0.0.0/html/07eff70b-f81f-6313-98a9-02d508f7c7e0.htm
Checks that image elements lie between two scalars
Return Value
res[i,j] = 255 if inrange, 0 otherwise
What is SetTo?
http://www.emgu.com/wiki/files/2.4.0/document/html/0309f41d-aa02-2c0d-767f-3d7d8ccc9212.htm
Copies scalar value to every selected element of the destination GpuMat: GpuMat(I)=value if mask(I)!=0
So it is.
Quoted from: http://blog.zsxsoft.com/post/24 (Chinese only) (CC BY-NC-ND)
Upvotes: 4
Reputation: 9381
Image<Bgr, Byte> img;
Image<Gray, Byte> grayImg = img.Convert<Gray, Byte>();
grayImg = img.InRange(new Bgr(minB, minG, minR), new Bgr(new Bgr(maxB, maxG, maxR);
it will only show your color(range) in binary and is the fastest way
But if you want to detect a certain range of colors AND replace them:
Image<Bgr, Byte> img;
for (int i = 0; i < img.ManagedArray.GetLength(0); i++)
{
for (int j = 0; j < img.ManagedArray.GetLength(1); j++)
{
Bgr currentColor = img[i, j];
if (currentColor.Blue >= minB && currentColor.Blue <= maxB && currentColor.Green >= minG && maxG <= trackBar13.Value && currentColor.Red >= minR && currentColor.Red <= maxR)
{
img[i, j] = new Bgr(B,G,R);
}
}
}
Upvotes: 1