php imagick像素迭代器与下一个和上一个像素相比

Question

$imagick = new \Imagick(realpath($imagePath));
$imageIterator = $imagick->getPixelIterator();

foreach ($imageIterator as $row => $pixels) { /* Loop through pixel rows */
    foreach ($pixels as $column => $pixel) { 
         if ($column % 2) {

How do I compare this pixel to the one above and below and the one to the left and right, I will be using isSimilar which I already understand

getNextIteratorRow/getPreviousIteratorRow maybe? Is their something similar for pixels?

}
    }
    $imageIterator->syncIterator(); 
}

That is the question how do I navigate from the current pixel to the one above, below, left and right.

Assistance much appreciated.

Answer 1

This is one of those problems that is probably best solved by just writing some code.

function processPixel($pixeLeft, $pixelMiddle, $pixelRight, $pixelAbove, $rowBelow)
{
    //Whatever it is you're doing.
}

function processRow($rowAbove, $rowMiddle, $rowBelow)
{
    for ($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 as $rowPixels) {

        $rowBelow = $rowPixels;

        foreach ($imageIterator as $rowPixels) {
            processRow($rowAbove, $rowMiddle, $rowBelow);
        }

        $rowAbove = $rowMiddle;
        $rowMiddle = $rowBelow;
    }

    // Finish last row with middle on the last row
    processRow($rowAbove, $rowMiddle, null);

    //Finish row of pixel below last row. This may not be necessary
    //depending on your algorithm,
    $rowAbove = $rowMiddle;
    processRow($rowAbove, null, null);
}

Just to note, this will be highly non-performant, aka slow as heck. It may (but not guaranteed) be faster to implement whatever it is you're trying to do as an FX operator. Example here and full documentation here.