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Search found 3 results on 1 pages for 'cgimagemaskcreate'.

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• Replace all white/nearly white pixels in a UIImage with alpha using CGImage?

  - by Peter Hajas

  Hi there, I have a UIImage with white background. I would like replace the white background/pixels with alpha-transparent pixels. I've looked at other questions on StackOverflow, along with Quartz documentation, but have yet to find a coherent "start-to-end" for this problem. How is this done?

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• Crashing when masking an image

  - by shameer

  I am trying to mask an image with a 'mask image". its work fine at first time. but when i try one more time with in the application with same mask image . Application crashed. but when trying with another mask image it works fine. Why this happens? pls help? Console shows ": CGImageMaskCreate: invalid mask bits/component: 4294967295." (UIImage*) maskImage:(UIImage *)image withMask:(UIImage *)maskImage { CGImageRef maskRef = maskImage.CGImage; CGImageRef mask = CGImageMaskCreate(CGImageGetWidth(maskRef), CGImageGetHeight(maskRef), CGImageGetBitsPerComponent(maskRef), CGImageGetBitsPerPixel(maskRef), CGImageGetBytesPerRow(maskRef), CGImageGetDataProvider(maskRef), NULL, false); CGImageRef masked = CGImageCreateWithMask([image CGImage], mask); UIImage *img2=[UIImage imageWithCGImage:masked]; CGImageRelease(maskRef); CGImageRelease(mask); CGImageRelease(masked); return img2; } fun1() { view.image=[self maskImage:image1 withMask:[UIImage imageNamed:@"image2.png"]]; } fun2() { view.image=[self maskImage:image1 withMask:[UIImage imageNamed:@"image2.png"]]; view.image=[self maskImage:image1 withMask:[UIImage imageNamed:@"image3.png"]]; } fun3() { view.image=[self maskImage:image1 withMask:[UIImage imageNamed:@"image2.png"]]; view.image=[self maskImage:image1 withMask:[UIImage imageNamed:@"image2.png"]]; } When calling fun1 and fun2 apllication works fine. Application crashing when calling fun3.

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• Masking to Transparent returns empty image

  - by Tibi

  Hi there, I'm trying to put white color in my images to transparent with the following code. Problem is that "CGImageRef maskedTransparent" is blank. I don't understand because the code I'm using is nearly a copy paste from the doc ... Any idea ? (UIImage*) maskImage:(UIImage *)image withMask:(UIImage *)maskImage { CGImageRef maskRef = maskImage.CGImage; CGImageRef mask = CGImageMaskCreate(CGImageGetWidth(maskRef), CGImageGetHeight(maskRef), CGImageGetBitsPerComponent(maskRef), CGImageGetBitsPerPixel(maskRef), CGImageGetBytesPerRow(maskRef), CGImageGetDataProvider(maskRef), NULL, false); CGImageRef masked = CGImageCreateWithMask([image CGImage], mask); //Array defining min & max RGB values to be transformed to transparent colors. float maskingMinMax[6] = {255, 255, 255, 255, 255, 255}; //masking image to remove range in maskinLinMax CGImageRef maskedTransparent = CGImageCreateWithMaskingColors(masked, maskingMinMax); return [UIImage imageWithCGImage:maskedTransparent]; }

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