CODEWITHSUNDEEP
phpgd
Othman
Othman

Reputation: 3018

Algorithm to find border color of an image in PHP

I am trying to find a way to get a border color from an image using php

I have tried to use this code, but this algorathim gives me all colors in any image. 

<?php 
function colorPalette($imageFile, $numColors, $granularity = 5) 
{ 
   $granularity = max(1, abs((int)$granularity)); 
   $colors = array(); 
   $size = @getimagesize($imageFile); 
   if($size === false) 
   { 
      user_error("Unable to get image size data"); 
      return false; 
   } 
   $img = @imagecreatefromjpeg($imageFile); 
   if(!$img) 
   { 
      user_error("Unable to open image file"); 
      return false; 
   } 
   for($x = 0; $x < $size[0]; $x += $granularity) 
   { 
      for($y = 0; $y < $size[1]; $y += $granularity) 
      { 
         $thisColor = imagecolorat($img, $x, $y); 
         $rgb = imagecolorsforindex($img, $thisColor); 
         $red = round(round(($rgb['red'] / 0x33)) * 0x33);  
         $green = round(round(($rgb['green'] / 0x33)) * 0x33);  
         $blue = round(round(($rgb['blue'] / 0x33)) * 0x33);  
         $thisRGB = sprintf('%02X%02X%02X', $red, $green, $blue); 
         if(array_key_exists($thisRGB, $colors)) 
         { 
            $colors[$thisRGB]++; 
         } 
         else 
         { 
            $colors[$thisRGB] = 1; 
         } 
      } 
   } 
   arsort($colors); 
   return array_slice(array_keys($colors), 0, $numColors); 
} 
// sample usage: 
$palette = colorPalette('rmnp8.jpg', 10, 4); 
echo "<table>\n"; 
foreach($palette as $color) 
{ 
   echo "<tr><td style='background-color:#$color;width:2em;'>&nbsp;</td><td>#$color</td></tr>\n"; 
} 
echo "</table>\n";

Also, I am trying to use this in order to build a design like these designs.

first second

Upvotes: 4

Views: 1722

Answers (1)

Aleks G
Aleks G

Reputation: 57336

The reason you're getting all colours in an image is because you're using a nested loop to iterate over pixels in the image. Instead, you should use two sequential loops: one to check horizontal borders and the other to check vertical ones, so your loop code will become something like this:

function checkColorAt(&$img, $x, $y, &$colors) {
    $thisColor = imagecolorat($img, $x, $y); 
    $rgb = imagecolorsforindex($img, $thisColor); 
    $red = round(round(($rgb['red'] / 0x33)) * 0x33);  
    $green = round(round(($rgb['green'] / 0x33)) * 0x33);  
    $blue = round(round(($rgb['blue'] / 0x33)) * 0x33);  
    $thisRGB = sprintf('%02X%02X%02X', $red, $green, $blue); 
    if(array_key_exists($thisRGB, $colors)) 
    { 
        $colors[$thisRGB]++; 
    } 
    else 
    { 
        $colors[$thisRGB] = 1; 
    }
}


$colors = array();
for($x = 0; $x < $size[0]; $x += $granularity) 
{ 
    checkColorAt(&$img, $x, $0, &$colors);
    checkColorAt(&$img, $x, $size[1] - 1, &$colors);
}

for($y = 0; $y < $size[1]; $y += $granularity) 
{ 
    checkColorAt(&$img, $0, $y, &$colors);
    checkColorAt(&$img, $size[0] - 1, $y, &$colors);
}

Upvotes: 5

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