Created
March 14, 2019 02:46
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Estimate an Imagick image's sharpness based on average color similarity between pixels in a grid.
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<?php | |
** | |
* Estimate image sharpnes based on color | |
* similarity in pixels in a grid. | |
* | |
* @param Imagick $img | |
* @return float | |
*/ | |
function GetImageSharpness($img) | |
{ | |
$w = $img->getImageWidth(); | |
$h = $img->getImageHeight(); | |
$grid = $w / 9; | |
$maximum = 0; | |
for ($x = $grid / 2; $x <= $w - $grid / 2; $x += $grid) { | |
$pixel = $img->getImagePixelColor($x, $grid / 2)->getColor(); | |
$r = $pixel['r']; | |
$g = $pixel['g']; | |
$b = $pixel['b']; | |
$v0 = floor(0.35 * $r + 0.50 * $g + 0.15 * $b); | |
for ($y = $grid / 2 + 1; $y <= $h - $grid / 2; $y++) { | |
$pixel = $img->getImagePixelColor($x, $y)->getColor(); | |
$r = $pixel['r']; | |
$g = $pixel['g']; | |
$b = $pixel['b']; | |
$v = floor(0.35 * $r + 0.50 * $g + 0.15 * $b); | |
if ($maximum < abs($v - $v0)) { | |
$maximum = abs($v - $v0); | |
$xmax = $x; | |
$ymax = $y; | |
} | |
$v0 = $v; | |
} | |
} | |
for ($y = $grid / 2; $y <= $h - $grid / 2; $y += $grid) { | |
$pixel = $img->getImagePixelColor($grid / 2, $y)->getColor(); | |
$r = $pixel['r']; | |
$g = $pixel['g']; | |
$b = $pixel['b']; | |
$v0 = floor(0.35 * $r + 0.50 * $g + 0.15 * $b); | |
for ($x = $grid / 2 + 1; $x <= $w - $grid / 2; $x++) { | |
$pixel = $img->getImagePixelColor($x, $y)->getColor(); | |
$r = $pixel['r']; | |
$g = $pixel['g']; | |
$b = $pixel['b']; | |
$v = floor(0.35 * $r + 0.50 * $g + 0.15 * $b); | |
if ($maximum < abs($v - $v0)) { | |
$maximum = abs($v - $v0); | |
$xmax = $x; | |
$ymax = $y; | |
} | |
$v0 = $v; | |
} | |
} | |
$maxv = 0; | |
$minv = 255; | |
for ($x = $xmax - 4; $x <= $xmax + 4; $x++) { | |
for ($y = $ymax - 4; $y <= $ymax + 4; $y++) { | |
$pixel = $img->getImagePixelColor($x, $y)->getColor(); | |
$r = $pixel['r']; | |
$g = $pixel['g']; | |
$b = $pixel['b']; | |
$v = floor(0.35 * $r + 0.50 * $g + 0.15 * $b); | |
if ($v > $maxv) $maxv = $v; | |
if ($v < $minv) $minv = $v; | |
} | |
} | |
return round(($maximum / (15 + $maxv - $minv)) * 27000 / 255, 2); | |
} |
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