How to sharply / blur uiimage in iphone?

Question

I have a view with UIImageViewand UIImage. How to make an image sharp or blurry with coregraphics?

Answer 1

Apple has an excellent sample program called GLImageProcessing , which includes a very fast blur / sharpen effect using OpenGL ES 1.1 (which means that it works on all iPhone, not just 3gs.)

If you are not good enough in OpenGL, the code can hurt you.

Answer 2

OpenGL ( ). , , , , , , . . :

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- (UIImage*)imageWithBlurAroundPoint:(CGPoint)point {
    CGRect             bnds = CGRectZero;
    UIImage*           copy = nil;
    CGContextRef       ctxt = nil;
    CGImageRef         imag = self.CGImage;
    CGRect             rect = CGRectZero;
    CGAffineTransform  tran = CGAffineTransformIdentity;
    int                indx = 0;

    rect.size.width  = CGImageGetWidth(imag);
    rect.size.height = CGImageGetHeight(imag);

    bnds = rect;

    UIGraphicsBeginImageContext(bnds.size);
    ctxt = UIGraphicsGetCurrentContext();

    // Cut out a sample out the image
    CGRect fillRect = CGRectMake(point.x - 10, point.y - 10, 20, 20);
    CGImageRef sampleImageRef = CGImageCreateWithImageInRect(self.CGImage, fillRect);

    // Flip the image right side up & draw
    CGContextSaveGState(ctxt);

    CGContextScaleCTM(ctxt, 1.0, -1.0);
    CGContextTranslateCTM(ctxt, 0.0, -rect.size.height);
    CGContextConcatCTM(ctxt, tran);

    CGContextDrawImage(UIGraphicsGetCurrentContext(), rect, imag);

    // Restore the context so that the coordinate system is restored
    CGContextRestoreGState(ctxt);

    // Cut out a sample image and redraw it over the source rect
    // several times, shifting the opacity and the positioning slightly
    // to produce a blurred effect
    for (indx = 0; indx < 5; indx++) {
        CGRect myRect = CGRectOffset(fillRect, 0.5 * indx, 0.5 * indx);
        CGContextSetAlpha(ctxt, 0.2 * indx);
        CGContextScaleCTM(ctxt, 1.0, -1.0);
        CGContextDrawImage(ctxt, myRect, sampleImageRef);
    }

    copy = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return copy;
}

Answer 3

API CoreImage. , CoreImage iPhone ( , ). , , IIRC, SIM-, .

AFAIK , , , , , . , tho, , , Photoshop .

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Answer 4

Take a look at the following libraries:

• https://github.com/coryleach/UIImageAdjust
• https://github.com/esilverberg/ios-image-filters
• https://github.com/cmkilger/CKImageAdditions