image-manipulation

I need to rotate an image by very small angle, like 1-5 degrees. Does OpenCV provide simple way of doing that? From reading docs i can assume that getAffineTransform() should be involved, but there is no direct example of doing something like: IplImage *rotateImage( IplImage *source, double angle); If you use OpenCV > 2.0 it is as easy as using namespace cv; Mat rotateImage(const Mat& source, double angle) { Point2f src_center(source.cols/2.0F, source.rows/2.0F); Mat rot_mat = getRotationMatrix2D(src_center, angle, 1.0); Mat dst; warpAffine(source, dst, rot_mat, source.size()); return dst; }

For a given multi-color PNG UIImage (with transparency), what is the best/Swift-idiomatic way to: create a duplicate UIImage find all black pixels in the copy and change them to red (return the modified copy) There are a few related questions on SO but I haven't been able to find something that works. You have to extract the pixel buffer of the image, at which point you can loop through, changing pixels as you see fit. At the end, create a new image from the buffer. In Swift 3, this looks like: func processPixels(in image: UIImage) -> UIImage? { guard let inputCGImage = image.cgImage else {

Is there any way to convert a bmp image to jpg/png without losing the quality in C#? Using Image class we can convert bmp to jpg but the quality of output image is very poor. Can we gain the quality level as good as an image converted to jpg using photoshop with highest quality? var qualityEncoder = Encoder.Quality; var quality = (long)<desired quality>; var ratio = new EncoderParameter(qualityEncoder, quality ); var codecParams = new EncoderParameters(1); codecParams.Param[0] = ratio; var jpegCodecInfo = <one of the codec infos from ImageCodecInfo.GetImageEncoders() with mime type = "image