提高裁剪图像质量

Question

我已经集成了一个模块，用户可以在网站上传图像，并可以根据自己的需要裁剪图像。但是，我正在使用该裁剪模块用于商务目的。我希望人们可以自己裁剪并上传他们的裁剪图像，以便我们可以根据该图像制作蛋糕。

    $output_filename=$output_directory.$uniquename.$type;
    $inc=0;
    while(@getimagesize($output_filename))
          $output_filename = $output_directory.$uniquename.$inc++;
    // resize the original image to size of editor
    $resizedImage = imagecreatetruecolor($imgW, $imgH);
    $cropped_rotated_image = imagecreatetruecolor($imgW, $imgH);
    $final_image=imagecreatetruecolor($cropW,$cropH);
    imagecopyresampled($resizedImage, $source_image, 0, 0, 0, 0, $imgW, $imgH, $imgInitW, $imgInitH);
    // rotate the rezized image
    $rotated_image = imagerotate($resizedImage, -$angle, 0);
    // find new width & height of rotated image
    $rotated_width = imagesx($rotated_image);
    $rotated_height = imagesy($rotated_image);
    // diff between rotated & original sizes
    $dx = $rotated_width - $imgW;
    $dy = $rotated_height - $imgH;
    // crop rotated image to fit into original rezized rectangle

    imagecolortransparent($cropped_rotated_image, imagecolorallocate($cropped_rotated_image, 0, 0, 0));
    imagecopyresampled($cropped_rotated_image, $rotated_image, 0, 0, $dx / 2, $dy / 2, $imgW, $imgH, $imgW, $imgH);
    // crop image into selected area
    //$final_image = imagecreatetruecolor($cropW, $cropH);
    imagecolortransparent($final_image, imagecolorallocate($final_image, 0, 0, 0));
    imagecopyresampled($final_image, $cropped_rotated_image, 0, 0, $imgX1, $imgY1, $cropW, $cropH, $cropW, $cropH);
    // finally output png image


    imagepng($final_image, $output_filename, $png_quality);

    //imagejpeg($final_image,$output_filename, $jpeg_quality);
     $response = Array(
        "status" => 'success',
        "url" => '/'.$output_filename,
    );
    imagedestroy($final_image);

原始图片：

裁剪图片：

裁剪图像的尺寸为500X500，现在的问题是原始图像的质量很好，但裁剪的图像有点褪色。我尝试使用图像卷积，但它也没有帮助。如何做我提高裁剪图像的质量？

我尝试的代码：

$sharpen = array(
         array(-1, -1,  -1),
         array(-1, 16, -1),
         array(-1, -1,  -1),
    // );
//  calculate the sharpen divisor
    $divisor = array_sum(array_map('array_sum', $sharpen));

// apply the matrix
     imageconvolution($final_image, $sharpen, $divisor, 0);

注意：

1. 裁剪器的固定宽度和高度意味着裁剪后的图像总是500X500。

2. 原始图片的尺寸大于500X500。