BalashovK
commented
1 year ago You are absolutely right.
Setting scalar produces funky result, exaggerated by saving to .jpg (saving to .png would give a better clue)
Replacing Scalar with Vec3b resolves the problem.
//var color = new Scalar(255, 255, 255); Vec3b color = new Vec3b(255, 255, 255);
Saved image looks exactly like your intended result.
Kjelldor
Summary of your issue
I am trying to add white pixels to an in-memory Mat, but instead it seems to add the RGB values spread out over the image.
Environment
Windows 11 pro Version 10.022621 AMD Ryzen 9 5900X GTX 3080 Ti
What did you do when you faced the problem?
I attempted to check whether or not my code was right by creating a single pixel example on a black canvas. This produced the same error, however.
Example code:
// Create an empty image of 20 by 20 with a black background. Mat image = new Mat(new Size(20, 20), MatType.CV_8UC3, new Scalar(0, 0, 0)); // Create a completely white brush var color = new Scalar(255, 255, 255); // Set the pixel of the image on coordinate 10,10 to white. image.Set(10, 10, color); // Save the image to disk Cv2.ImWrite("Test.jpg", image);
Output:
I apologize for the small size, however, by keeping it this small and only referencing a single pixel, I feel like the idea comes across better.
What did you intend to be?
I intended it to be a black square with a single white pixel, like so:
this was made with opencv in python, though also a different implementation, the issue doesnt seem to be with opencv itself.