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GD
PHP Manual

GD and Image Functions

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GD
PHP Manual
User Contributed Notes
GD and Image Functions
chuckstudios at gmail dot com
26-Nov-2008 05:18
I wrote a simple function to convert an image resource to PGM (portable graymap) in order to feed it to an OCR program. It works just like the rest of the image output functions, and will convert to grayscale for you:

<?php
    function imagepgm($image, $filename = null)
    {
        $pgm = "P5 ".imagesx($image)." ".imagesy($image)." 255\n";
        for($y = 0; $y < imagesy($image); $y++)
        {
            for($x = 0; $x < imagesx($image); $x++)
            {
                $colors = imagecolorsforindex($image, imagecolorat($image, $x, $y));
                $pgm .= chr(0.3 * $colors["red"] + 0.59 * $colors["green"] + 0.11 * $colors["blue"]);
            }
        }
        if($filename != null)
        {
            $fp = fopen($filename, "w");
            fwrite($fp, $pgm);
            fclose($fp);
        }
        else
        {
            return $pgm;
        }
    }
 ?>
dev at kingthief dot com
28-Mar-2008 04:20
I've developed a well-documented, fairly rock-solid API for creating on the fly, anti-aliased, rounded corner images, including full alpha transparency support for all you PNG lovers.

go here to download the package:
http://sourceforge.net/projects/roundedphp/

go here for a live demo:
http://dev.kingthief.com/demos/roundedphp/

Installation is similar to PEAR.

Enjoy!
ph_corp at yahoo dot fr
23-Dec-2007 11:19
<?php

 /**
HSL/RGB conversion functions
very useful for a lot of applications
**/

 function RBGtoHSL ( $R, $G, $B )
{

    $var_R = ( $R / 255 );
    $var_G = ( $G / 255 );
    $var_B = ( $B / 255 );

    $var_Min = min( $var_R, $var_G, $var_B )
    $var_Max = max( $var_R, $var_G, $var_B )
    $del_Max = $var_Max - $var_Min

    $L = ( $var_Max + $var_Min ) / 2;

    if ( $del_Max == 0 )
    {
       $H = 0
       $S = 0
    }
    else
    {
        if ( $L < 0.5 )
        {
            $S = $del_Max / ( $var_Max + $var_Min );
        }
        else
        {
            $S = $del_Max / ( 2 - $var_Max - $var_Min );
        }

        $del_R = ( ( ( $var_Max - $var_R ) / 6 ) + ( $del_Max / 2 ) ) / $del_Max;
        $del_G = ( ( ( $var_Max - $var_G ) / 6 ) + ( $del_Max / 2 ) ) / $del_Max;
        $del_B = ( ( ( $var_Max - $var_B ) / 6 ) + ( $del_Max / 2 ) ) / $del_Max;

        if ( $var_R == $var_Max )
        {
            $H = $del_B - $del_G;
        }
        else if ( $var_G == $var_Max )
        {
            $H = ( 1 / 3 ) + $del_R - $del_B;
        }
        else if ( $var_B == $var_Max )
        {
            $H = ( 2 / 3 ) + $del_G - $del_R;
        }

        if ( $H < 0 )
        {
            $H += 1;
        }
        if ( $H > 1 )
        {
            $H -= 1
        }

    }

    return array( $H, $S, $L );

}

function HuetoRGB( $v1, $v2, $vH )
{
    if ( $vH < 0 )
    {
        $vH += 1;
    }
    if ( $vH > 1 )
    {
        $vH -= 1;
    }
    if ( ( 6 * $vH ) < 1 )
    {
        return ( $v1 + ( $v2 - $v1 ) * 6 * $vH );
    }
    if ( ( 2 * $vH ) < 1 )
    {
        return ( $v2 );
    }
    if ( ( 3 * $vH ) < 2 )
    {
        return ( $v1 + ( $v2 - $v1 ) * ( ( 2 / 3 ) - $vH ) * 6 );
    }
    return ( $v1 )
}

function HSLtoRGB ( $H, $S, $L )
{

    if ( $S == 0 )
    {
        $R = $L * 255;
        $G = $L * 255;
        $B = $L * 255;
    }
    else
    {
        if ( $L < 0.5 )
        {
            $var_2 = $L * ( 1 + $S );
        }
        else
        {
            $var_2 = ( $L + $S ) - ( $S * $L );
        }

        $var_1 = 2 * $L - $var_2;

        $R = 255 * HuetoRGB( $var_1, $var_2, $H + ( 1 / 3 ) );
        $G = 255 * HuetoRGB( $var_1, $var_2, $H );
        $B = 255 * HuetoRGB( $var_1, $var_2, $H - ( 1 / 3 ) );
    }

    return array( $R, $G, $B );

}

function distance ( $R1, $G1, $B1, $R2, $G2, $B2 )
{
    $result = sqrt ( ( $R1 - $R2 )*( $R1 - $R2 ) + ( $G1 - $G2 )*( $G1 - $G2 ) + ( $B1 - $B2 )*( $B1 - $B2 ) );
    return ( $result );
}

 ?>
shd at earthling dot net
28-Mar-2006 12:44
If you happen to need a way to output a Windows BMP file (e.g. when using the PEAR ExcelWriter), feel free to use the following code:

<?php
 function imagebmp ($im, $fn = false)
{
    if (!$im) return false;
           
    if ($fn === false) $fn = 'php://output';
    $f = fopen ($fn, "w");
    if (!$f) return false;
           
    //Image dimensions
    $biWidth = imagesx ($im);
    $biHeight = imagesy ($im);
    $biBPLine = $biWidth * 3;
    $biStride = ($biBPLine + 3) & ~3;
    $biSizeImage = $biStride * $biHeight;
    $bfOffBits = 54;
    $bfSize = $bfOffBits + $biSizeImage;
           
    //BITMAPFILEHEADER
    fwrite ($f, 'BM', 2);
    fwrite ($f, pack ('VvvV', $bfSize, 0, 0, $bfOffBits));
           
    //BITMAPINFO (BITMAPINFOHEADER)
    fwrite ($f, pack ('VVVvvVVVVVV', 40, $biWidth, $biHeight, 1, 24, 0, $biSizeImage, 0, 0, 0, 0));
           
    $numpad = $biStride - $biBPLine;
    for ($y = $biHeight - 1; $y >= 0; --$y)
    {
        for ($x = 0; $x < $biWidth; ++$x)
        {
            $col = imagecolorat ($im, $x, $y);
            fwrite ($f, pack ('V', $col), 3);
        }
        for ($i = 0; $i < $numpad; ++$i)
            fwrite ($f, pack ('C', 0));
    }
    fclose ($f);
    return true;
}
 ?>

It works the same way as regular imagejpeg/imagepng do and only supports GD2.0 true colour bitmaps (which is what's required by ExcelWriter).
felipensp at gmail dot com
13-Mar-2006 05:17
Representation decimal of a color in hexadecimal for use on functions of library GD.

<?php

    // Representation hexadecimal
    $var = '#FFFFFF';

    function getRgbFromGd($color_hex) {

        return array_map('hexdec', explode('|', wordwrap(substr($color_hex, 1), 2, '|', 1)));

    }
   
    print_r(getRgbFromGd($var));

    // Output: Array ( [0] => 255 [1] => 255 [2] => 255 )

 ?>
peter dot hulstaert at gmail dot com
06-Jan-2006 01:18
While I was searching for a good way to draw a graph, I stumbled on skumar2k15's script.

I have taken the liberty to improve multiple aspects of it.

1. The array can grow and shrink in size, the graph will adjust accordingly.
2. All the values in the array are recalculated so they won't get bigger than the height of the graph.
3. I inserted the possibility to keep a percentage off the height away from the edge.
4. You can adjust the size of the grid.
5. Everything will adjust when you change the height of width.

<?
header("Content-type: image/png");

 // Define variables
 $Values=array(50,90,30,155,50,40,320,50,40,86,240,128,650,540,320);
 $imgWidth=500;
 $imgHeight=200;
 $grid=25;
 $graphspacing=0.05;

 //Creation of new array with hight adjusted values
 while (list($key, $val) = each($Values))
    {if($val>$max){$max=$val;}}

for ($i=0; $i<count($Values); $i++){
 $graphValues[$i] = $Values[$i] * (($imgHeight*(1-$graphspacing))/$max);
}
 // Create image and define colors

 $image=imagecreate($imgWidth, $imgHeight);
 $colorWhite=imagecolorallocate($image, 255, 255, 255);
 $colorGrey=imagecolorallocate($image, 192, 192, 192);
 $colorBlue=imagecolorallocate($image, 0, 0, 255);

 // Create border around image
 imageline($image, 0, 0, 0, $imgHeight, $colorGrey);
 imageline($image, 0, 0, $imgWidth, 0, $colorGrey);
 imageline($image, $imgWidth-1, 0, $imgWidth-1, $imgHeight-1, $colorGrey);
 imageline($image, 0, $imgHeight-1, $imgWidth-1, $imgHeight-1, $colorGrey);

 // Create grid
 for ($i=1; $i<($imgWidth/$grid); $i++)
    {imageline($image, $i*$grid, 0, $i*$grid, $imgHeight, $colorGrey);}
for ($i=1; $i<($imgHeight/$grid); $i++)
    {imageline($image, 0, $i*$grid, $imgWidth, $i*$grid, $colorGrey);}

 // Create line graph
 if($imgWidth/$grid>count($graphValues)){$space=$grid;}
else{$space = $imgWidth/(count($graphValues)-1);}

for ($i=0; $i<count($graphValues)-1; $i++)
    {imageline($image, $i*$space, ($imgHeight-$graphValues[$i]), ($i+1)*$space, ($imgHeight-$graphValues[$i+1]), $colorBlue);}

 // Output graph and clear image from memory
 imagepng($image);
 imagedestroy($image);
 ?>
michal-ok at o2 dot pl
18-Oct-2005 09:29
The image sharpen function (by Alex R. Austin) provided below seems to be very resource hungry and I couldn't make it work on two different servers - trying to sharpen a 413 x 413 image I ended up with "Fatal error: Allowed memory size of 8388608 bytes exhausted" or "Internal Server Error" or the script terminated without notice. Because I had no priviliges to change the default memory limit on these servers I started looking for other sharpen functions. I have come across a php Unsharp Mask function which works like a charm on both of the servers I dealt with. It can be found at http://vikjavev.no/hovudsida/umtestside.php.
mslemko
09-Oct-2005 07:09
For fedora core 4 users that find that the gd library isn't installed, you can issue the command (as root)

# yum install php-gd

it should download and install the gd library. You will need to restart apache... phpinfo() should then tell you "GD Support     enabled".
timeshifting at gmail dot com
24-Aug-2005 10:39
To sharpen an image, rather than using the code below that produces a sharpening filter with php, use the built-in GD function "imageconvolution" which is designed for this purpose. Matrices can be used for sharpening, blurring, edge detection, etc, ala Photoshop.

A sharpening example:

<?php

$sharpenMatrix = array(-1,-1,-1,-1,16,-1,-1,-1,-1);
 $divisor = 8;
 $offset = 0;

 imageconvolution($myImage, $sharpenMatrix, $divisor, $offset);

 ?>

Below is some information on building different kinds of matrices. (If you have photoshop (or PSP, GIMP) you can test out your matrices before applying them in PHP)

http://loriweb.pair.com/8udf-basics.html (covers blurs)
http://loriweb.pair.com/8udf-sharpen.html
http://loriweb.pair.com/8udf-edges.html
http://loriweb.pair.com/8udf-emboss.html
jeff at lushmedia dot com
04-Nov-2003 04:52
I wrote an online overview of the image functions that people might find useful. In addition to a general overview of the various function categories and code samples, I have included many interactive examples of the functions, allowing viewers to experiment with the parameters, and seeing the results in real time. The presentation is located at New York PHP
http://www.nyphp.org/content/presentations/GDintro/
sellout at NoSpAm dot dharmadevil dot com
16-Apr-2003 05:06
A fun little function to output UPC-A 11-digit barcodes.
Thanks to barcodeisland.com for the specs.

<?php

 function UPCAbarcode($code) {
  $lw = 2; $hi = 100;
  $Lencode = array('0001101','0011001','0010011','0111101','0100011',
                   '0110001','0101111','0111011','0110111','0001011');
  $Rencode = array('1110010','1100110','1101100','1000010','1011100',
                   '1001110','1010000','1000100','1001000','1110100');
  $ends = '101'; $center = '01010';
  /* UPC-A Must be 11 digits, we compute the checksum. */
  if ( strlen($code) != 11 ) { die("UPC-A Must be 11 digits."); }
  /* Compute the EAN-13 Checksum digit */
  $ncode = '0'.$code;
  $even = 0; $odd = 0;
  for ($x=0;$x<12;$x++) {
    if ($x % 2) { $odd += $ncode[$x]; } else { $even += $ncode[$x]; }
  }
  $code.=(10 - (($odd * 3 + $even) % 10)) % 10;
  /* Create the bar encoding using a binary string */
  $bars=$ends;
  $bars.=$Lencode[$code[0]];
  for($x=1;$x<6;$x++) {
    $bars.=$Lencode[$code[$x]];
  }
  $bars.=$center;
  for($x=6;$x<12;$x++) {
    $bars.=$Rencode[$code[$x]];
  }
  $bars.=$ends;
  /* Generate the Barcode Image */
  $img = ImageCreate($lw*95+30,$hi+30);
  $fg = ImageColorAllocate($img, 0, 0, 0);
  $bg = ImageColorAllocate($img, 255, 255, 255);
  ImageFilledRectangle($img, 0, 0, $lw*95+30, $hi+30, $bg);
  $shift=10;
  for ($x=0;$x<strlen($bars);$x++) {
    if (($x<10) || ($x>=45 && $x<50) || ($x >=85)) { $sh=10; } else { $sh=0; }
    if ($bars[$x] == '1') { $color = $fg; } else { $color = $bg; }
    ImageFilledRectangle($img, ($x*$lw)+15,5,($x+1)*$lw+14,$hi+5+$sh,$color);
  }
  /* Add the Human Readable Label */
  ImageString($img,4,5,$hi-5,$code[0],$fg);
  for ($x=0;$x<5;$x++) {
    ImageString($img,5,$lw*(13+$x*6)+15,$hi+5,$code[$x+1],$fg);
    ImageString($img,5,$lw*(53+$x*6)+15,$hi+5,$code[$x+6],$fg);
  }
  ImageString($img,4,$lw*95+17,$hi-5,$code[11],$fg);
  /* Output the Header and Content. */
  header("Content-Type: image/png");
  ImagePNG($img);
}

 UPCAbarcode('12345678901');

 ?>
 

 
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