CODEWITHSUNDEEP
c#imageopencvemgucvaffinetransform
Jander Friebe
Jander Friebe

Reputation: 23

Shift Emgu.CV.Image to the right using WarpAffine()

my goal is, to shift an Image an x-amount of pixels to the right. I guess this can be achieved by using WarpAffine. This is at least what my reseach tells me. I used quite a variety of different approaches, like:

CvInvoke.WarpAffine(realImage, transformedImage, transformationMatrix, new Size(realImage.Size);

//or while m is the Mat used to create realImage
transImage.WarpAffine(m,Emgu.CV.CvEnum.Inter.Area,Emgu.CV.CvEnum.Warp.Default,Emgu.CV.CvEnum.BorderType.Default,new Gray());

I get the Exeption: 

Exception thrown: 'Emgu.CV.Util.CvException' in Emgu.CV.Platform.NetStandard.dll
[ WARN:0] global E:\bb\cv_x86\build\opencv\modules\videoio\src\cap_msmf.cpp (436) `anonymous-namespace'::SourceReaderCB::~SourceReaderCB terminating async callback

I guess I am using it the wrong way, but there is no suiting example online for me to learn from. Does anyone has a clean way to explain it to me?

Thank you in advance!

Upvotes: 0

Views: 1069

Answers (1)

Aaron Jones
Aaron Jones

Reputation: 1170

If you are shifting the pixels x amount to the right, I assume that there would be black empty pixels on the left side? If so, you could create an ROI and cut off some pixels on the right, since you are shifting all pixels to the right, and copy the image onto another image.

//The image that you want to shift pixels with
Image<Bgr, byte> inputImage = new Image<Bgr, byte>(1000, 1000);

//The output image
Image<Bgr, byte> image = new Image<Bgr, byte>(990, 1000);

//Create the roi, with 10 pixels cut off from the right side because of the shift
inputImage.ROI = new Rectangle(0, 0, inputImage.Width - 10, inputImage.Height);

inputImage.CopyTo(image);

CvInvoke.ImShow("The Output", image);
CvInvoke.WaitKey(0);

EDIT

Now lets say you want to keep that black stripe on the left side of the image as well. Doing this is very similar to the code above, but only with a few modifications.

//The image that you want to shift pixels with
Image<Bgr, byte> inputImage = new Image<Bgr, byte>(1000, 1000);

//The output image
Image<Bgr, byte> image = new Image<Bgr, byte>(1000, 1000);

//Create the roi, with 10 pixels cut off from the right side because of the shift
inputImage.ROI = new Rectangle(0, 0, inputImage.Width - 10, inputImage.Height);

//The image we want to shift, the same one we created a ROI with, 
//has the dimensions 990 X 1000 and the output image has 
//dimensions of 1000 x 1000. Unfortunately, in order to paste 
//an image onto another image, they need to be the same dimensions. 
//How do we do this? We must create an ROI with the output image 
//that has the same dimensions as the input image. 

image.ROI = new Rectangle(10, 0, image.Width, image.Height);

//Now we can past the image onto the output because the dimensions match
inputImage.CopyTo(image);

//Inorder to make our output seem normal, we must empty the ROI of the output image
image.ROI = Rectangle.Empty;

CvInvoke.ImShow("The Output", image);
CvInvoke.WaitKey(0);

Upvotes: 0

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