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PHP PNG image file parsing

Hi, I've just started messing with PHP and Apache, and knocked up the below quick script as a quirky idea. It's meant to read the hex colours of each pixel of a PNG file, and then print them as the colour for the background of a table division in a html page.

It does result in a grid of coloured cubes but my problem is the colour is wrong compared to the source image viewed enlarged in, say, the Gimp.

I suspect the problem lies in the int->hex code I copied from the PHP Manual, with the bitshifting and masking.

PHP Code:




<html> 
<head> 
<title>Pixel Picker</title> 
</head> 
<body> 
 
<?php     
    $file = "/usr/share/icons/crystalsvg/32x32/apps/kmenu.png"; 
    $image = ImageCreateFromPng($file); 
    $size = GetImageSize($file); 
    $width = $size[0]; 
    $height = $size[1]; 
     
    echo "<table>"; 
     
    for ($i = 0; $i < $height; $i++) { 
     
    echo "<tr>" ; 
     
        for ($j = 0; $j < $width; $j++) { 
        $rgb = ImageColorAt($image, $j, $i); 
        $r = ($rgb >> 16) & 0xFF; 
        $g = ($rgb >> 8) & 0xFF; 
        $b = $rgb & 0xFF; 
 
        echo "<td bgcolor=#"; 
        echo base_convert($r, 10, 16); 
        echo base_convert($g, 10, 16); 
        echo base_convert($b, 10, 16); 
        echo "\">&nbsp&nbsp</td>"; 
        } 
     
    echo "</tr>"; 
    } 
    echo "</table>"; 
        ?> 
 
</body> 
</html>

Just wondering if anyone had a quick solution. Plus pointing out any bad coding habits would be appreciated. :)

all i can think of would be that php may be set to only work with web standard colors, only 255. wheras your image may b in high, or true, colors, a lot more.

Well I improved the code and it works now well, except for not using the transparency values of the pixels. :)

PHP Code:




<html> 
<head> 
<title>Pixel Picker</title> 
</head> 
<body> 
 
<?php     
    $file = "/usr/share/icons/crystalsvg/32x32/apps/kmenu.png"; 
    $image = ImageCreateFromPng($file); 
    $size = GetImageSize($file); 
    $width = $size[0]; 
    $height = $size[1]; 
     
    echo "<table>\n"; 
     
    for ($i = 0; $i < $height; $i++) { 
     
    echo "<tr>\n" ; 
     
        for ($j = 0; $j < $width; $j++) { 
        $rgb = ImageColorAt($image, $j, $i); 
        $r = ($rgb >> 16) & 0xFF; 
        $g = ($rgb >> 8) & 0xFF; 
        $b = $rgb & 0xFF; 
 
        echo "<td bgcolor=\"#"; 
        $red = strtoupper(base_convert($r, 10, 16)); 
        $green = strtoupper(base_convert($g, 10, 16)); 
        $blue =  strtoupper(base_convert($b, 10, 16)); 
         
        if (strlen($red) == 1) { 
        echo "0"; 
        echo $red; 
        } 
        else { 
        echo $red; 
        } 
        if (strlen($green) == 1) { 
        echo "0"; 
        echo $green; 
        } 
        else { 
        echo $green; 
        } 
        if (strlen($blue) == 1) { 
        echo "0"; 
        echo $blue; 
        } 
        else { 
        echo $blue; 
        } 
         
        echo "\">&nbsp&nbsp</td>"; 
        } 
     
    echo "\n</tr>\n"; 
    } 
    echo "</table>\n"; 
        ?> 
 
</body> 
</html>

You can also short your code by replace your last if blocks by conditional statement like :

PHP Code:




//instead of: 
if (strlen($red) == 1) { 
        echo "0"; 
        echo $red; 
} else { 
        echo $red; 
}  
// I would do: 
echo (strlen($red) == 1) ? "0$red" : $red;