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Questions tagged [cgimage]

CGImage represents a drawable image object in Core Graphics (the low-level procedural drawing API for iOS and Mac OS X).

563 questions
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Trim UIImage border

Here's an example of an image I would like to trim. I want to get rid of the borders around the image (in this case the top and bottom black bars). I found a library on Github: CKImageAdditions, however it doesn't seem to work. When I pass in a…
runmad
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Converting NSData to CGImage and then back to NSData makes the file too big

I have built a camera using AVFoundation. Once my AVCaptureStillImageOutput has completed its captureStillImageAsynchronouslyFromConnection:completionHandler: method, I create a NSData object like this: NSData *imageData =…
Will
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takepicture() vs UIGetScreenImage()

I'm trying to build a QRCodeReader for a project our research group is working on for the iPhone. After much research I found the program called QuickMark. This program scans automatically for QRCodes. What it appears to do is load the UIImagePicker…
Oni
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iPhone - UIImage Leak, CGBitmapContextCreateImage Leak

Alright I am having a world of difficulty tracking down this memory leak. When running this script I do not see any memory leaking, but my objectalloc is climbing. Instruments points to CGBitmapContextCreateImage > create_bitmap_data_provider >…
bbullis21
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The joys of realtime gif decoding

I have written this gist to convert gif data downloaded from the this incredible site and turn that into a mp4 that is playable with MPMoviePlayerController. The problem is, I must download the entire gif and then start converting. I would like to…
Paul de Lange
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Converting UIImage to CGImage cause rotation of Image

I am trying to crop image by my custom cropper. Not from the UIImagePickerController's. Now for that I am showing the Image captured from Image Picker in a UIImgeView by handling UIImagePicker's delegate: -…
Kapil Choubisa
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Converting from UIImage/CGImage to Leptonica Pix structure

I want to use Leptonica library in my iOS application for image processing and have troubles figuring out how to get Leptonica's Pix structure from UIImage. What I suggest to do is something like the following: UIImage *image = [UIImage…
mym
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iOS How to perform rotation on a cgimage efficiently (up to 125 frames)?

I have two images, let's call them image A and image B. I'm trying to rotate and scale image A and to draw it on top of image B at specific location. I use the function and method below to : 1. rotate and scale my image 2. Draw Image A into Image B…
Pierre Addoum
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CGImageCreateWithMaskingColors leaving border when removing color

I'm using the code below to make the color magenta transparent: UIImage *inputImage = [UIImage imageWithData:UIImageJPEGRepresentation(anchorWithMask, 1.0)]; const float colorMasking[6] = {0.0, 255.0, 0.0, 2.0, 0.0, 255.0}; CGImageRef imageRef =…
MB.
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Solution Like Trash Can Animation

I would like to put the undocumented trash can animation in my program. The call method is: + (void)animateToolbarItemIndex:(unsigned)index duration:(double)duration target:(id)target didFinishSelector:(SEL)selector; Can anyone figure out what I…
T.J.
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New CALayer.contents does not display until view is resized

I have a CALayer that needs to display frames of video. Every time a frame is rendered (as a CGImageRef), this method is called: - (void)displayFrame:(CGImageRef)frame { [view layer].contents = (id)frame; } What's strange is that this, at…
spudwaffle
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setColor on NSBitmapImageRep not working in Swift

I'm trying to figure out how setColor works. I have the following code: lazy var imageView:NSImageView = { let imageView = NSImageView(frame: view.frame) return imageView }() override func viewDidLoad() { …
Ben A.
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How can I change this black shade (gradient) to some colored shade?

I want to use the actual color of the image, apply alpha effect pixel by pixel and create something like this but in colored way. How can I do it? I tried giving it a color but it turned my image from white to pink. In this code, I go pixel by pixel…
Saad Tahir
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Check if subsection of UIImage is light or dark

I'm attempting to overlay a chevron button that will allow the user to dismiss the current view. The colour of the chevron should be light on dark images, and dark on light images. I've attached a screenshot of what I'm describing. However, there…
Avery Vine
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generateCGImagesAsynchronously produces duplicate images according to actualTime

I am able to get the frames from a video using AVAssetImageGenerator, and I do so using generateCGImagesAsynchronously. Whenever the result succeeds, I print the requestedTime in seconds as well as the actualTime for that image. In the end, however,…
bruteforce
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