如何在图像中找到最暗的像素,图像中出现的最大？因此,要找到我可以比其他像素看到更多的最暗像素.
在这里,我发现了我的图像噪点,并用白色对其进行了着色,但是如何找到最暗的像素呢？我尝试在rgb数组元素中找到巫婆的出现次数是最大的,但是我发现白色像素到了.这是我的代码的一部分：

<?php

    function components($color) {
      return array(($color >> 16) & 0xFF, ($color >> 8) & 0xFF, $color & 0xFF);
    }

    // Performs "similarity test" of 2 colors
    function isSimilar($color1, $color2) {
      $c1 = components($color1);
      $c2 = components($color2);
      for ($i = 0; $i < 3; $i++) {
        $k = ($c1[$i] > $c2[$i]) ? ($c1[$i] - $c2[$i]) / $c2[$i] : ($c2[$i] - $c1[$i]) / $c1[$i];
        if ($k > 0.35) return false;
      }
      return true;
    }

    function LoadJpeg($imgname)
    {
        $count = 0;
        /* Attempt to open */
        $im = @imagecreatefrompng($imgname);
        $imagedata = getimagesize($imgname);

        $n = $imagedata[0];
        $m = $imagedata[1];
        for($i=0; $i<$imagedata[0]; $i++){
            for($j=0; $j<$imagedata[1]; $j++){
                $rgb[$i][$j] = imagecolorat($im, $i, $j);
                //echo $rgb[$i][$j];
                //echo "<br>";
            }
        }



    /*    for ($k = 0; $k < $n; $k++)
        {
            for ($l = 0; $l < $m; $l++)
            {
                for ($i = 0; $i < $n; $i++)
                {
                    for ($j = 0; $j < $m; $j++)
                    {
                        if (($i+1 == $n) && ($j+1 == $m))
                        {
                            continue;
                        }
                        else
                        {
                            if ($j+1 == $m and $rgb[$i][$j] > $rgb[$i+1][0])
                            {
                                $t = $rgb[$i][$j];
                                $rgb[$i][$j] = $rgb[$i+1][0];
                                $rgb[$i+1][0] = $t;
                            }
                            else
                            {
                                if ($rgb[$i][$j] > $rgb[$i][$j+1])
                                {
                                    $t = $rgb[$i][$j];
                                    $rgb[$i][$j] = $rgb[$i][$j+1];
                                    $rgb[$i][$j+1] = $t;
                                }
                            }
                        }
                    }
                }
            }
        }*/



        for($i=0; $i<$imagedata[0]-3; $i++){
            for($j=0; $j<$imagedata[1]-3; $j++){
                if (isSimilar($rgb[$i][$j], $rgb[$i][$j + 3]) or isSimilar($rgb[$i][$j], $rgb[$i + 3][$j])) 
                {
                    #echo "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAa";
                    $count = $count + 1;
                    //echo "<br> <br>";
                    //echo $count;
                    //$red = imagecolorallocate($im, 255, 255, 255);

                    imagesetpixel($im, $i, $j, 16777215);
                    cropCentered($im,20,20);
                }                  

            }
        }

        return $im;
    }

    function cropCentered($img, $w, $h)
    {
      $cx = $img->getWidth() / 2;
      $cy = $img->getHeight() / 2;
      $x = $cx - $w / 2;
      $y = $cy - $h / 2;
      if ($x < 0) $x = 0;
      if ($y < 0) $y = 0;
      return $img->crop(0, 0, $w, $h);
    }

    header('Content-Type: image/jpeg');

    $img = LoadJpeg('1.png');




    imagejpeg($img,null, 100);

    ?>

解决方法:

您需要使用不同于RGB的颜色模型-在这种情况下,HSL非常有用,因为它包含“亮度”成分.基于此组件,我们可以判断某种颜色是比另一种颜色浅还是深.有几种将RGB转换为HSL的方法,我使用了Wikipedia article中描述的方法(请参阅HSL“ bi-hexcone”模型)：

<?php

// Returns whether c2 is darker than c1
function isDarker($c1, $c2) {
  // Find L (lightness) component in a HSL model
  $max1 = max($c1);
  $min1 = min($c1);
  $l1 = ($max1 + $min1) / 2;
  $max2 = max($c2);
  $min2 = min($c2);
  $l2 = ($max2 + $min2) / 2;

  // Compare colors based on L component (lower means darker)
  return $l2 < $l1;
}

// Assuming colors are stored in a 2-dimensional $rgb array
$rowCount = count($rgb);
$colCount = count($rgb[0]);
$darkest = $rgb[0][0];
for ($i = 0; $i < $rowCount; $i++) {
  for ($j = 0; $j < $colCount; $j++) {
    if (isDarker($darkest, $rgb[$i][$j])) {
      $darkest = $rgb[$i][$j];
      // Optionally you can save the indices $i and $j
    }
  }
}