On an image frame, I use
void ellipse(Mat& img, Point center, Size axes, double angle, double startAngle, double endAngle, const Scalar& color, int thickness=1, int lineType=8, int shift=0)
to draw an ellipse and I want to set the ellipse color to green [ RGB value : (165, 206, 94) ].
So I set the parameter const Scalar& color
to
cv::Scalar(94.0, 206.0, 165.0, 0.0); // as BGR order, suppose the value is 0.0 - 255.0
cv::Scalar(94.0/255.0, 206.0/255.0, 165.0/255.0, 0.0); // suppose the value is 0.0 - 1.0
I also tried RGB alternative.
CV_RGB(165.0, 206.0, 94.0); // as RGB order, suppose the value is 0.0 - 255.0
CV_RGB(165.0/255.0, 206.0/255.0, 94.0/255.0); // suppose the value is 0.0 - 1.0
But the color being displayed is white [ RGB value (255, 255, 255) ] , not the desired green one.
What I missed at this point? Any suggestion please. Thank you.
EDIT:
Let me put whole related code here. According to OpenCV iOS - Video Processing, this is the CvVideoCamera
config in - (void)viewDidLoad;
:
self.videoCamera = [[CvVideoCamera alloc] initWithParentView:imgView];
[self.videoCamera setDelegate:self];
self.videoCamera.defaultAVCaptureDevicePosition = AVCaptureDevicePositionFront;
self.videoCamera.defaultAVCaptureSessionPreset = AVCaptureSessionPreset352x288;
self.videoCamera.defaultAVCaptureVideoOrientation = AVCaptureVideoOrientationPortrait;
self.videoCamera.defaultFPS = 30;
self.videoCamera.grayscaleMode = NO;
[self.videoCamera adjustLayoutToInterfaceOrientation:UIInterfaceOrientationPortrait];
Then after [self.videoCamera start];
called, the (Mat&)image
would be captured and can be processed in the CvVideoCameraDelegate method - (void)processImage:(Mat&)image;
and here are the code to draw an ellipse:
- (void)processImage:(Mat&)image {
NSLog(@"image.type(): %d", image.type()); // got 24
// image.convertTo(image, CV_8UC3); // try to convert image type, but with or without this line result the same
NSLog(@"image.type(): %d", image.type()); // also 24
cv::Scalar colorScalar = cv::Scalar( 94, 206, 165 );
cv::Point center( image.size().width*0.5, image.size().height*0.5 );
cv::Size size( 100, 100 );
cv::ellipse( image, center, size, 0, 0, 360, colorScalar, 4, 8, 0 );
}
Eventually, the ellipse is still in white, not the desired green one.
Set alpha to 255 can fix this problem. Scalar(94,206,165,255)