如何在iphone中锐化/模糊uiimage？

Question

我有一个视图UIImageView和UIImage设置.如何使用coregraphics使图像清晰或模糊？

Answer 1

Apple有一个名为GLImageProcessing的优秀示例程序,它包含使用OpenGL ES 1.1的非常快速的模糊/锐化效果(意味着它适用于所有iPhone,而不仅仅是3gs).

如果您对OpenGL没有相当的经验,那么代码可能会让您头痛.

Answer 2

沿着OpenGL路线走下去感觉就像疯了一样满足我的需求(模糊图像上的触摸点).相反,我实现了一个简单的模糊过程,它接受一个触点,创建一个包含该触摸点的矩形,对该点中的图像进行采样,然后在源矩形顶部上下颠倒重绘样本图像几次稍微偏移,略微不同的不透明度.这会产生一个相当不错的穷人的模糊效果,而没有疯狂的代码和复杂性.代码如下:

- (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;
}