core-image

I'm creating a color picker for iOS. I would like to enable the user to select the brightness (luminance) and have the color wheel reflect this change. I'm using Core Image to modify the brightness with the CIColorControls filter. Here's my code: -(CIImage *)oldPhoto:(CIImage *)img withBrightness:(float)intensity { CIFilter *lighten = [CIFilter filterWithName:@"CIColorControls"]; [lighten setValue:img forKey:kCIInputImageKey]; [lighten setValue:@((intensity * 2.0) - 1.0) forKey:@"inputBrightness"]; return lighten.outputImage; } Here's how the color wheel looks with intensity = 0.5

What are the major differences between the Core Image and GPUImage frameworks (besides GPUImage being open source)? At a glance their interfaces seem pretty similar... Applying a series of filters to an input to create an output. I see a few small differences, such as the easy to use LookupFilter that GPUImage has. I am trying to figure out why someone would choose one over the other for a photo filtering application. Brad Larson As the author of GPUImage, you may want to take what I say with a grain of salt. I should first say that I have a tremendous amount of respect for the Core Image team

I am writing an app that lets users take a picture and then edit it. I am working on implementing tools with UISliders for brightness/contrast/saturation and am using the Core Image Filter class to do so. When I open the app, I can take a picture and display it correctly. However, if I choose to edit a picture, and then use any of the described slider tools, the image will rotate counterclockwise 90 degrees. Here's the code in question: - (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view. self.navigationItem.hidesBackButton = YES; //hide default nav /

Recently, I've been trying to set up a CIColorCube on a CIImage to create a custom effect. Here's what I have now: uint8_t color_cube_data[8*4] = { 0, 0, 0, 1, 255, 0, 0, 1, 0, 255, 0, 1, 255, 255, 0, 1, 0, 0, 255, 1, 255, 0, 255, 1, 0, 255, 255, 1, 255, 255, 255, 1 }; NSData * cube_data =[NSData dataWithBytes:color_cube_data length:8*4*sizeof(uint8_t)]; CIFilter *filter = [CIFilter filterWithName:@"CIColorCube"]; [filter setValue:beginImage forKey:kCIInputImageKey]; [filter setValue:@2 forKey:@"inputCubeDimension"]; [filter setValue:cube_data forKey:@"inputCubeData"]; outputImage = [filter

I'm not asking about the exact code but the overall idea. Here is my problem: I'm trying to create something similar to filter choosing UI in Photos app. I've tried multiple approaches and all of them have their drawbacks. 1) I've tried using Operation and OperationQueue with a collection view, which prefetching is enabled. This loads the viewController fast but drops frames while scrolling. 2) Right now I'm using a scroll view and GCD but it loads the viewController too long (because it applies all filters to all the buttons inside it at once), but then it scrolls smoothly. NOTE: To answer

My goal is to create a CGPath that matches the outline of a SKSpriteNode. This would be useful in creating glows/outlines of SKSpriteNodes as well as a path for physics. One thought I have had, but I have not really worked much at all with CIImage, so I don't know if there is a way to access/modify images on a pixel level. Then maybe I would be able to port something like this to Objective-C : http://www.sakri.net/blog/2009/05/28/detecting-edge-pixels-with-marching-squares-algorithm/ Also very open to other approaches that make this process automated as opposed to me creating shape paths for

I am currently building a camera app prototype which should recognize sheets of paper lying on a table. The clue about this is that it should do the recognition in real time, so I capture the video stream of the camera, which in iOS 5 can easily be done with the AV foundation. I looked at here and here They are doing some basic object recognition there. I have found out that using OpenCV library in this realtime environment does not work in a performant way. So what I need is an algorithm to determine the edges of an image without OpenCV. Does anyone have some sample code snippets which lay

I'm trying to implement the built-in iOS 5 face detection API. I'm using an instance of UIImagePickerController to allow the user to take a photo and then I'm trying to use CIDetector to detect facial features. Unfortunately, featuresInImage always returns an array of size 0. Here's the code: - (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info { UIImage* picture = [info objectForKey:UIImagePickerControllerOriginalImage]; NSNumber *orientation = [NSNumber numberWithInt: [picture imageOrientation]]; NSDictionary *imageOptions =