How to find the Dominant color in image?

There is a PHP class developed that handles this, named color extract. However, know that doing this on the server side will require substantial system resources. You may wish to instead do this with canvas.

To find the most "dominant" color in an image, meaning the color that is most prevalent in the image: you'd need to create a histogram of the image.

Here is an the code from this article on how to create a histogram in PHP. (Website has gone off line several times)

<?php
$source_file = "test_image.jpg";

// histogram options

$maxheight = 300;
$barwidth = 2;

$im = ImageCreateFromJpeg($source_file);

$imgw = imagesx($im);
$imgh = imagesy($im);

// n = total number or pixels

$n = $imgw*$imgh;

$histo = array();

for ($i=0; $i<$imgw; $i++)
{
        for ($j=0; $j<$imgh; $j++)
        {

                // get the rgb value for current pixel

                $rgb = ImageColorAt($im, $i, $j);

                // extract each value for r, g, b

                $r = ($rgb >> 16) & 0xFF;
                $g = ($rgb >> 8) & 0xFF;
                $b = $rgb & 0xFF;

                // get the Value from the RGB value

                $V = round(($r + $g + $b) / 3);

                // add the point to the histogram

                $histo[$V] += $V / $n;

        }
}

// find the maximum in the histogram in order to display a normated graph

$max = 0;
for ($i=0; $i<255; $i++)
{
        if ($histo[$i] > $max)
        {
                $max = $histo[$i];
        }
}

echo "<div style='width: ".(256*$barwidth)."px; border: 1px solid'>";
for ($i=0; $i<255; $i++)
{
        $val += $histo[$i];

        $h = ( $histo[$i]/$max )*$maxheight;

        echo "<img src=\"img.gif\" width=\"".$barwidth."\"
height=\"".$h."\" border=\"0\">";
}
echo "</div>";
?> 

In that example $max is your most "dominant" color.

Sounds like a delightful code to write! I made a function awhile back that goes through every pixel and adds a shade to each one. What you could do is:

For Each Pixel, find the highest color (r,g,or b) and do the math ($colorG++ or something)

at the end, find out what one is the largest, and there would be your highest rgb shade.

I wonder what color would come out if you used the resulting rgb value...

Try this: http://www.coolphptools.com/color_extract.

The Image Color Extract PHP class pulls the most common colors (in percentages) out of an image file. The color values are in hexadecimal.