Change language:

Edit Report a Bug

GD and Image Funzioni

Indice dei contenuti

add a note add a note

User Contributed Notes 12 notes

up
5
ph_corp at yahoo dot fr
5 years ago
<?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 );
}

?>
up
5
shd at earthling dot net
7 years ago
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).
up
4
michal-ok at o2 dot pl
8 years ago
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.
up
4
mslemko
8 years ago
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".
up
4
jeff at lushmedia dot com
10 years ago
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/
up
5
felipensp at gmail dot com
7 years ago
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 )

?>
up
3
ingo at jache dot de
2 years ago
I know this might look somewhat superfluous to others, but i once came across a situation where i needed a *strong* blur on an image without having ImageMagick installed. Executing the convolution-filter several times on the same image is awfully slow and still doesn't give a good blur.

The function below accepts a truecolor-image and a blur-factor between 0.0 and 1.0. Beware: It's still quite slow.

<?php

    function blurImage($srcimg,$blur)
    {
        $blur = $blur*$blur;
        $blur = max(0,min(1,$blur));
   
        $srcw = imagesx($srcimg);
        $srch = imagesy($srcimg);
       
        $dstimg = imagecreatetruecolor($srcw,$srch);
   
        $f1a = $blur;
        $f1b = 1.0 - $blur;

   
        $cr = 0; $cg = 0; $cb = 0;
        $nr = 0; $ng = 0; $nb = 0;

        $rgb = imagecolorat($srcimg,0,0);
        $or = ($rgb >> 16) & 0xFF;
        $og = ($rgb >> 8) & 0xFF;
        $ob = ($rgb) & 0xFF;

        //-------------------------------------------------
        // first line is a special case
        //-------------------------------------------------
        $x = $srcw;
        $y = $srch-1;
        while ($x--)
        {
            //horizontal blurren
            $rgb = imagecolorat($srcimg,$x,$y);
            $cr = ($rgb >> 16) & 0xFF;
            $cg = ($rgb >> 8) & 0xFF;
            $cb = ($rgb) & 0xFF;
   
            $nr = ($cr * $f1a) + ($or * $f1b);
            $ng = ($cg * $f1a) + ($og * $f1b);
            $nb = ($cb * $f1a) + ($ob * $f1b);   

            $or = $nr;
            $og = $ng;
            $ob = $nb;
           
            imagesetpixel($dstimg,$x,$y,($nr << 16) | ($ng << 8) | ($nb));
        }
        //-------------------------------------------------

        //-------------------------------------------------
        // now process the entire picture
        //-------------------------------------------------
        $y = $srch-1;
        while ($y--)
        {

            $rgb = imagecolorat($srcimg,0,$y);
            $or = ($rgb >> 16) & 0xFF;
            $og = ($rgb >> 8) & 0xFF;
            $ob = ($rgb) & 0xFF;

            $x = $srcw;
            while ($x--)
            {
                //horizontal
                $rgb = imagecolorat($srcimg,$x,$y);
                $cr = ($rgb >> 16) & 0xFF;
                $cg = ($rgb >> 8) & 0xFF;
                $cb = ($rgb) & 0xFF;
               
                $nr = ($cr * $f1a) + ($or * $f1b);
                $ng = ($cg * $f1a) + ($og * $f1b);
                $nb = ($cb * $f1a) + ($ob * $f1b);   
   
                $or = $nr;
                $og = $ng;
                $ob = $nb;
               
               
                //vertical
                $rgb = imagecolorat($dstimg,$x,$y+1);
                $vr = ($rgb >> 16) & 0xFF;
                $vg = ($rgb >> 8) & 0xFF;
                $vb = ($rgb) & 0xFF;
               
                $nr = ($nr * $f1a) + ($vr * $f1b);
                $ng = ($ng * $f1a) + ($vg * $f1b);
                $nb = ($nb * $f1a) + ($vb * $f1b);   
   
                $vr = $nr;
                $vg = $ng;
                $vb = $nb;
               
                imagesetpixel($dstimg,$x,$y,($nr << 16) | ($ng << 8) | ($nb));
            }
       
        }
        //-------------------------------------------------
        return $dstimg;       

    }

   
    $srcimg = imagecreatefromjpeg("test.jpg");
    $dstimg = blurImage($srcimg,0.2);

    header('Content-type: image/jpeg');
    echo( imagejpeg($dstimg) );
    exit();
   
   
?>
up
3
dev at kingthief dot com
5 years ago
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!
up
3
peter dot hulstaert at gmail dot com
7 years ago
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);
?>
up
3
timeshifting at gmail dot com
8 years ago
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
up
3
chuckstudios at gmail dot com
5 years ago
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;
        }
    }
?>
up
0
sellout at NoSpAm dot dharmadevil dot com
10 years ago
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');

?>
add a note add a note