php imagick pixel iterator compare to next and previous pixels -

$imagick = new \imagick(realpath($imagepath)); $imageiterator = $imagick->getpixeliterator();  foreach ($imageiterator $row => $pixels) { /* loop through pixel rows */     foreach ($pixels $column => $pixel) {           if ($column % 2) { 

how compare pixel 1 above , below , 1 left , right, using issimilar understand

getnextiteratorrow/getpreviousiteratorrow maybe? similar pixels?

}     }     $imageiterator->synciterator();  } 

that question how navigate current pixel 1 above, below, left , right.

assistance appreciated.

this 1 of problems best solved writing code.

function processpixel($pixeleft, $pixelmiddle, $pixelright, $pixelabove, $rowbelow) {     //whatever you're doing. }  function processrow($rowabove, $rowmiddle, $rowbelow) {     ($x = 0; $x < count($pixels); $x++) {         $pixelabove = null;         $pixelbelow = null;         $pixeleft = null;         $pixelright = null;         $pixelmiddle = $pixels[0];          if (($x - 1) >= 0) {             $pixelleft = $pixels[$x - 1];         }          if (($x + 1) < count($pixels)) {             $pixelright = $pixels[$x + 1];         }          if ($rowabove != null) {             $pixelabove = $rowabove[$x];         }         if ($rowbelow != null) {             $rowbelow = $rowbelow[$x];         }          processpixel($pixeleft, $pixelmiddle, $pixelright, $pixelabove, $rowbelow)     } }  function processimageiterator($imageiterator) {     $rowabove = null;     $rowmiddle = null;     $rowbelow = null;      foreach ($imageiterator $rowpixels) {          $rowbelow = $rowpixels;          foreach ($imageiterator $rowpixels) {             processrow($rowabove, $rowmiddle, $rowbelow);         }          $rowabove = $rowmiddle;         $rowmiddle = $rowbelow;     }      // finish last row middle on last row     processrow($rowabove, $rowmiddle, null);      //finish row of pixel below last row. may not necessary     //depending on algorithm,     $rowabove = $rowmiddle;     processrow($rowabove, null, null); } 

just note, highly non-performant, aka slow heck. may (but not guaranteed) faster implement whatever you're trying fx operator. example here , full documentation here.