如何使用CGImageRef來循環調整大小而不增加像素的圖像部分？

Question

我想創建一個看起來好像2個圖像互相交織的效果。所以我縮放了第一張圖片作爲背景，並且我在背景上使用了幾個UIIMageView來循環播放第二張圖片，以提供我想要的外觀。這適用於我使用不需要縮放以適合顯示尺寸的圖像，但是當我使用UIGraphics調整圖像大小時，出現圖像質量下降的問題。任何建議將不勝感激。

圖片1.JPG爲2112×2816

圖片2.JPG是2000×3008

UIImage *bgImage = [UIImage imageNamed:@"1.jpg"]; 
UIImageView *bgView = [[UIImageView alloc] initWithImage:bgImage]; 
bgView.contentMode = UIViewContentModeScaleToFill; 
bgView.frame = CGRectMake(0,0,CGRectGetWidth(self.view.frame), (CGRectGetWidth(self.view.frame)/bgImage.size.width) * bgImage.size.height); 

bgView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth; 
[self.view addSubview:bgView]; 

UIImage *frontImage = [UIImage imageNamed:@"2.jpg"]; 
CGSize newSize = CGSizeMake(CGRectGetWidth(self.view.frame), (CGRectGetWidth(self.view.frame)/frontImage.size.width) * frontImage.size.height); 
UIGraphicsBeginImageContextWithOptions(newSize, YES, 0.0); 
[frontImage drawInRect:CGRectMake(0,0,newSize.width,newSize.height)]; 
UIImage *scaledImage = UIGraphicsGetImageFromCurrentImageContext(); 
UIGraphicsEndImageContext(); 

int count = 0; 
int varX = 10; 
int varY = 10; 

CGFloat width = self.view.frame.size.width; 
CGFloat height = self.view.frame.size.height; 
CGFloat tileWidth = width/varX; 
CGFloat tileHeight = height/varY; 

for (int x = 0; x < varX; x++) { 
    for (int y = 0; y < varY; y++) { 

     NSLog(@"%f, %f, %f, %f",x*tileWidth, y*tileHeight, tileWidth, tileHeight); 

     CGImageRef scaledRef = CGImageCreateWithImageInRect(scaledImage.CGImage, CGRectMake(x*tileWidth, y*tileHeight, tileWidth, tileHeight)); 
     UIImage *image = [UIImage imageWithCGImage:scaledRef scale:scaledImage.scale orientation:scaledImage.imageOrientation]; 
     UIImageView *bgx = [[UIImageView alloc] initWithImage:image]; 
     CGImageRelease(scaledRef); 

     bgx.frame = CGRectMake((x*tileWidth), (y*tileHeight), tileWidth, tileHeight); 
     bgx.backgroundColor = [UIColor yellowColor]; 
     bgx.contentMode = UIViewContentModeTopLeft; 

     if(count%2==0){ 
      [self.view addSubview:bgx]; 
     } 
     count++; 
    } 
    count++; 
} 

Answer 1

我能夠通過改變第二線在我的循環來解決我的問題：

CGImageRef scaledRef = CGImageCreateWithImageInRect(scaledImage.CGImage, CGRectMake(x*(tileWidth*2), y*(tileHeight*2), tileWidth*2, tileHeight*2)); 

我之前的輸出結果是2倍，但我不知道爲什麼會這樣。

任何洞察力是讚賞。