Here’s some sample code that will print a bunch of relevant info about an image, as well as a dump of the image’s pixel data. It will work on images with alpha channels, as well as images without. The code will even work on images that are not in the RGB color space, though I … Read more
Note: This is a solution for iOS creating a UIImage. For a solution for macOS and NSImage, see this answer. Your only problem is that the data types in your PixelData structure need to be UInt8. I created a test image in a Playground with the following: public struct PixelData { var a: UInt8 var … Read more
Converting a CGImage to an array of intensity values My function takes a CGImage and returns an array of unsigned 8-bit integers as well as the width and height of the image. I wrote this code for use with grayscale images. Extending this to color should be a matter of changing Gray to RGB and … Read more
Using CGImageDestination and passing kUTTypePNG is the correct approach. Here’s a quick snippet: @import MobileCoreServices; // or `@import CoreServices;` on Mac @import ImageIO; BOOL CGImageWriteToFile(CGImageRef image, NSString *path) { CFURLRef url = (__bridge CFURLRef)[NSURL fileURLWithPath:path]; CGImageDestinationRef destination = CGImageDestinationCreateWithURL(url, kUTTypePNG, 1, NULL); if (!destination) { NSLog(@”Failed to create CGImageDestination for %@”, path); return NO; } … Read more
I’ve had the same stuttering problem, with some help I figured out the proper solution here: Non-lazy image loading in iOS Two important things to mention: Don’t use UIKit methods in a worker-thread. Use CoreGraphics instead. Even if you have a background thread for loading and decompressing images, you’ll still have a little stutter if … Read more
-(UIImage*) rotate:(UIImage*) src andOrientation:(UIImageOrientation)orientation { UIGraphicsBeginImageContext(src.size); CGContextRef context=(UIGraphicsGetCurrentContext()); if (orientation == UIImageOrientationRight) { CGContextRotateCTM (context, 90/180*M_PI) ; } else if (orientation == UIImageOrientationLeft) { CGContextRotateCTM (context, -90/180*M_PI); } else if (orientation == UIImageOrientationDown) { // NOTHING } else if (orientation == UIImageOrientationUp) { CGContextRotateCTM (context, 90/180*M_PI); } [src drawAtPoint:CGPointMake(0, 0)]; UIImage *img=UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return img; … Read more
I needed a version that preserved the alpha channel, so I modified the code posted by Dutchie432: @implementation UIImage (grayscale) typedef enum { ALPHA = 0, BLUE = 1, GREEN = 2, RED = 3 } PIXELS; – (UIImage *)convertToGrayscale { CGSize size = [self size]; int width = size.width; int height = size.height; // … Read more