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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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CGImage/UIImage lazily loading on UI thread causes stutter

My program displays a horizontal scrolling surface tiled with UIImageViews from left to right. Code runs on the UI thread to ensure that newly-visible UIImageViews have a freshly loaded UIImage assigned to them. The loading happens on a background…
JBx
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NSImage to cv::Mat and vice versa

while working with OpenCV I need to convert a NSImage to an OpenCV multi-channel 2D matrix (cvMat) and vice versa. What's the best way to do it? Greets, Dom
dom
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iPhone CGContextRef CGBitmapContextCreate unsupported parameter combination

In my application I need to resize and crop some images, stored locally and online. I am using Trevor Harmon's tutorial which implements UIImage+Resize. On my iPhone 4(iOS 4.3.1) everything works OK, I have no problems. But on my iPhone 3G (iOS 3.2)…
Andrei Neacsu
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CGBitmapContextCreateImage - vm_copy failed - iPhone SDK

I am having an issue using CGBitmapContextCreateImage in my iPhone app. I am using AV Foundation Framework to grab camera frames using this method: - (void)captureOutput:(AVCaptureOutput *)captureOutput…
Brett
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2 answers

Most efficent way to create a CALayer with an image in it?

I am wondering what the most efficient way is to make a CALayer with an image in it. I know you can load a UIImage and then call [image CGImage] but is this the best way of going about it? As far as I can tell from Apple's documentation this is the…
Michael Gaylord
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2 answers

How to determine and interpret the pixel format of a CGImage

I'm loading this (very small) image using: UIImage* image = [UIImage named:@"someFile.png"]; The image is 4x1 and it contains a red, green, blue and white pixel from left to right, in that order. Next, I get the pixel data out of the underlying…
Matt Comi
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Crop UIImage to alpha

I have a rather large, almost full screen image that I'm going to be displaying on an iPad. The image is about 80% transparent. I need to, on the client, determine the bounding box of the opaque pixels, and then crop to that bounding box. Scanning…
MikeQ
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CGImage gets stretched in CALayer

I have an NSMutableArray of CGImage objects. All the images have different dimensions ( 80x20 px, 200x200 px, 10x10 px, etc...) I'm trying to animate these in CALayer which has 256x256 pixels size. The animation works, but my CGImages get stretched…
PrimeSeventyThree
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CGImageSource to CGImage?

I got this following code that access a PHAsset. I need to pass a CGImage out of this: let imageManager = PHImageManager.defaultManager() imageManager.requestImageDataForAsset(self.asset!, options: nil, resultHandler:{ (data, responseString,…
Gizmodo
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4 answers

Swift accessing EXIF Dictionary

Info: Using Swift and the CGImageSourceCreateWithURL function. I am attempting to load a file from a URL and then edit a dictionary which has all the data from that particular photo. This is the code from the .swift file. let url = NSURL(string:…
user3423554
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CGImage of UIImage return NULL

I created a function for splitting an image into multiple images, but when I take take the CGImage of the UIImage, the CGImage returns NULL NSArray* splitImage(UIImage* image,NSUInteger pieces) { NSLog(@"width: %f,…
Otium
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add/pass (exif) thumbnail to CGImageDestinationRef

On CGImageDestinationRef Apple's reference it mentions that It can contain thumbnail images as well as properties for each image. The part with the properties works nice, by setting the properties parameter when adding a image to the…
alex-i
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iPhone - CGImageCreateWithImageInRect rotating some camera roll pictures

I am working on a pixelate application for iPhone. Because the pictures taken with the iPhone 4 camera are too big and therefore the application is working really slow when updating the pixelated picture, I am trying to create tiles of the picture…
Andrei Neacsu
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4 answers

Image segmentation for iOS

I need a way to transform image containing human into a image containing only body sihlouette in one color. First i took a look at Canny edge detector (OpenCV implementation), but this may lead to problems with background of the image. I`ve tried…
Ivan Alek
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Properly crop an image obtained from the photo library

I've been working on this all day, and have looked at lots of questions here on SO and google, but so far I can't come up with anything quite right. I have taken a photo on an iPad running iOS 5.1.1 and cropped it using the Photos app. I then get a…
lnafziger
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