调整图像大小而不损失质量的最佳方法是什么?
问题描述:
其实我已经使用了以下两种方法进行图像大小调整,但我的客户说我的图像质量很差,所以我想知道图像大小调整的最佳方法。 我只是截取屏幕截图并将480x320大小的UIImage的截图发送到以下函数。调整图像大小而不损失质量的最佳方法是什么?
- (UIImage *)makeResizedImage:(CGSize)newSize quality:(CGInterpolationQuality)interpolationQuality image:(UIImage *)inImage{
NSLog(@"OriginalImage%f",inImage.size.width);
CGRect newRect = CGRectIntegral(CGRectMake(0, 0, newSize.width, newSize.height));
CGImageRef imageRef = [inImage CGImage];
// Compute the bytes per row of the new image
size_t bytesPerRow = CGImageGetBitsPerPixel(imageRef)/CGImageGetBitsPerComponent(imageRef) * newRect.size.width;
bytesPerRow = (bytesPerRow + 15) & ~15; // Make it 16-byte aligned
// Build a bitmap context that's the same dimensions as the new size
CGContextRef bitmap = CGBitmapContextCreate(NULL,
newRect.size.width,
newRect.size.height,
CGImageGetBitsPerComponent(imageRef),
bytesPerRow,
CGImageGetColorSpace(imageRef),
CGImageGetBitmapInfo(imageRef));
CGContextSetInterpolationQuality(bitmap, interpolationQuality);
// Draw into the context; this scales the image
CGContextDrawImage(bitmap, newRect, imageRef);
// Get the resized image from the context and a UIImage
CGImageRef resizedImageRef = CGBitmapContextCreateImage(bitmap);
UIImage *resizedImage = [UIImage imageWithCGImage:resizedImageRef];
NSLog(@"ResizedImage%f",resizedImage.size.width);
NSLog(@"ResizedImage%f",resizedImage.size.height);
// Clean up
CGContextRelease(bitmap);
CGImageRelease(resizedImageRef);
return resizedImage;
}
或
- (UIImage *)resizedImage:(CGSize)newSize
transform:(CGAffineTransform)transform
drawTransposed:(BOOL)transpose
interpolationQuality:(CGInterpolationQuality)quality {
CGRect newRect = CGRectIntegral(CGRectMake(0, 0, newSize.width, newSize.height));
CGRect transposedRect = CGRectMake(0, 0, newRect.size.height, newRect.size.width);
CGImageRef imageRef = self.CGImage;
// Build a context that's the same dimensions as the new size
CGContextRef bitmap = CGBitmapContextCreate(NULL,
newRect.size.width,
newRect.size.height,
CGImageGetBitsPerComponent(imageRef),
0,
CGImageGetColorSpace(imageRef),
CGImageGetBitmapInfo(imageRef));
// Rotate and/or flip the image if required by its orientation
CGContextConcatCTM(bitmap, transform);
// Set the quality level to use when rescaling
CGContextSetInterpolationQuality(bitmap, quality);
// Draw into the context; this scales the image
CGContextDrawImage(bitmap, transpose ? transposedRect : newRect, imageRef);
// Get the resized image from the context and a UIImage
CGImageRef newImageRef = CGBitmapContextCreateImage(bitmap);
UIImage *newImage = [UIImage imageWithCGImage:newImageRef];
// Clean up
CGContextRelease(bitmap);
CGImageRelease(newImageRef);
return newImage;
}
请告诉我,有没有其他的方法来调整图像大小,而不会失去其质量
答
您可以尝试集成库,而不是滚动您自己。
这是一个:http://code.google.com/p/simple-iphone-image-processing/
+0
感谢马修为你提供的帮助。 – 2011-05-23 19:17:39
他们是如何失去质量?像素化,模糊,拉伸或其他? – blindjesse 2011-05-14 06:36:44