ios - 使用 UIGraphics 调整照片大小但最终图像有点模糊

Question

我正在尝试使用 UIGraphics 调整图像的大小。图片是用相机拍的，我用的是这段代码:

 CGSize origImageSize = photograph.size;

    //this saves as 140*140 for retina
    CGRect newRect = CGRectMake(0, 0, 70, 70);

    //scaling ratio
    float ratio = MAX(newRect.size.width/origImageSize.width, newRect.size.height/origImageSize.height);


    UIGraphicsBeginImageContextWithOptions(newRect.size, NO, 0.0);


    CGRect projectRect;
    projectRect.size.width= ratio*origImageSize.width;
    projectRect.size.height=ratio*origImageSize.height;
    //center the image
    projectRect.origin.x= ((newRect.size.width-projectRect.size.width)/2);
    projectRect.origin.y=((newRect.size.height-projectRect.size.height)/2);
    [photograph drawInRect:projectRect];

    //get the image from the image context
    UIImage *smallImage = UIGraphicsGetImageFromCurrentImageContext();

出于某种原因，最终照片不是那么清晰，有点模糊。我在这里做错了什么吗？任何指针将不胜感激。谢谢

Answer 1

我假设您正确计算了矩形。然后确保使用完整的矩形。非整数值可能会导致亚像素渲染。

通过 CGRectIntegral 运行您的 projectRect 以获得完整的矩形，然后使用它来渲染您的图像。

projectRect = CGRectIntegral(projectRect);