imagecopymergegray()

(PHP 4 >= 4.0.6, PHP 5, PHP 7)

用灰度拷贝并合并图像的一部分

说明

imagecopymergegray(resource $dst_im,resource $src_im,int $dst_x,int $dst_y,int $src_x,int $src_y,int $src_w,int $src_h,int $pct): bool

将$src_im图像中坐标从$src_x，src_y开始，宽度为$src_w，高度为$src_h的一部分拷贝到$dst_im图像中坐标为$dst_x和$dst_y的位置上。两图像将根据$pct来决定合并程度，其值范围从 0 到 100。当$pct= 0 时，实际上什么也没做，当为 100 时本函数和imagecopy()完全一样。

本函数和imagecopymerge()完全一样只除了合并时通过在拷贝操作前将目标像素转换为灰度级来保留了原色度。

Note:

本函数添加于 PHP 4.0.6。

gray effect :)
<?php
header('content-type:image/png');
$url_img = 'my_image.png';
$img = imagecreatefrompng($url_img);
$x = imagesx($img);
$y = imagesy($img);
$gray_img = imagecreatetruecolor($x, $y);
imagecolorallocate($gray_img, 0, 0, 0);
for ($i = 0; $i < $x; $i++) {
 for ($j = 0; $j < $y; $j++) {
  $rgb = imagecolorat($img, $i, $j);
  $r = ($rgb >> 16) & 0xFF;
  $g = ($rgb >> 8) & 0xFF;
  $b = $rgb & 0xFF;
   //for gray mode $r = $g = $b
  $color = max(array($r, $g, $b));
  $gray_color = imagecolorexact($new_img, $color, $color,  $color);
   imagesetpixel($gray_img, $i, $j, $gray_color);
  }
}
?>

// Using the same code I found here on php.net, 
// I was able to figure out how to convert GIF (or any other
// format GD supports) to CIP format. CIP is the image
// format for Cisco IP Phones... 7905/7940 and 7960 
// models... Hope someone finds this useful and make it 
// better... 
/////// GIF2CIP PHP code ///////
// Convert image in memory to grayscale
  $img_width = imageSX($im2);
  $img_height = imageSY($im2);
  // convert to grayscale
  // note: this will NOT affect your original image, unless
  // originalFileName and destinationFileName are the same
  for ($y = 0; $y <$img_height; $y++) { 
    for ($x = 0; $x <$img_width; $x++) { 
      $rgb = imagecolorat($im2, $x, $y);
      $red = ($rgb >> 16) & 0xFF;
      $green = ($rgb >> 8) & 0xFF;
      $blue = $rgb & 0xFF;
      $gray = round(.299*$red + .587*$green + .114*$blue);
      
      // shift gray level to the left
      $grayR = $gray << 16; // R: red
      $grayG = $gray << 8;  // G: green
      $grayB = $gray;    // B: blue
      
      // OR operation to compute gray value
      $grayColor = $grayR | $grayG | $grayB;
      // set the pixel color
      imagesetpixel ($im2, $x, $y, $grayColor);
      imagecolorallocate ($im2, $gray, $gray, $gray);
    }
  }
/////////////////////////////////////////////////////////
  // Modifies palette to only 4-colors (CIP Images on 7905/7940 & 7960 is 2-bit color)
  ImageTrueColorToPalette2($im2,FALSE,4);
  // Basic header for CIP Image files...
  header ("Content-type: text/xml");
  echo "<CiscoIPPhoneImage> ";
  echo "<LocationX>-1</LocationX> ";
  echo "<LocationY>-1</LocationY> ";
  echo "<Width>132</Width> ";
  echo "<Height>65</Height> ";
  echo "<Depth>2</Depth> ";
  echo "<Data>";
// get image dimensions (almost same code as above)
  $img_width = imageSX($im2);
  $img_height = imageSY($im2);
  // convert to grayscale
  // note: this will NOT affect your original image, unless
  // originalFileName and destinationFileName are the same
  for ($y = 0; $y <$img_height; $y++) { 
    for ($x = 0; $x+4 <$img_width; $x = $x+4) 
    { 
      for ($ix = 0; $ix < 4; $ix++)
      {
        $rgb = imagecolorat($im2, $x + $ix, $y);
        // I came up with this translation on my own
        // Some smart person is bound to perfect it
        if ($rgb=="2") {$rgb=0;$Gray1[$ix] = $rgb;continue;}
        if ($rgb=="0") {$rgb=2;$Gray1[$ix] = $rgb;continue;}
        if ($rgb=="1") {$rgb=1;$Gray1[$ix] = $rgb;continue;}
        if ($rgb=="3") {$rgb=3;$Gray1[$ix] = $rgb;continue;}
      }
        $gray1 = $Gray1[0];
        $gray2 = $Gray1[1] << 2;
        $gray3 = $Gray1[2] << 4;
        $gray4 = $Gray1[3] << 6;
        
        // Pack 4 pixels into a single byte for CIP images
        $grey = $gray1 | $gray2 | $gray3 | $gray4;
        // CIP image data is sent in HEX, strtoupper is not really needed.
        $code = strtoupper(dechex($grey)); 
        // My quick fix to padding single HEX values
        if (strlen($code)==1) $code = "0".$code;
        echo $code;
        
    }
  }
  echo "</Data>";
  echo "<Title>$myvar</Title> ";
  echo "<Prompt>$city</Prompt> ";
  echo "</CiscoIPPhoneImage>";
  exit;

In addition to code_couturier too: his code will produce blue pictures, because the value he uses to set the pixel color (the code is incomplete: I first thought it should be $gray) is between 0 and 255, which corresponds to blue levels.
To convert the picture to grayscale, use the following code:
<?php
  // replace with your files
  $originalFileName  = "colorPicture.jpg";
  $destinationFileName = "bwPicture.jpg";
  
  // create a copy of the original image
  // works with jpg images
  // fell free to adapt to other formats ;)
  $fullPath = explode(".",$originalFileName);
  $lastIndex = sizeof($fullPath) - 1;
  $extension = $fullPath[$lastIndex];
  if (preg_match("/jpg|jpeg|JPG|JPEG/", $extension)){
    $sourceImage = imagecreatefromjpeg($originalFileName);
  }
  // get image dimensions
  $img_width = imageSX($sourceImage);
  $img_height = imageSY($sourceImage);
  // convert to grayscale
  // note: this will NOT affect your original image, unless
  // originalFileName and destinationFileName are the same
  for ($y = 0; $y <$img_height; $y++) { 
    for ($x = 0; $x <$img_width; $x++) { 
      $rgb = imagecolorat($sourceImage, $x, $y);
      $red  = ($rgb >> 16) & 0xFF;
      $green = ($rgb >> 8) & 0xFF;
      $blue = $rgb & 0xFF;
      $gray = round(.299*$red + .587*$green + .114*$blue);
      
      // shift gray level to the left
      $grayR = $gray << 16;  // R: red
      $grayG = $gray << 8;  // G: green
      $grayB = $gray;     // B: blue
      
      // OR operation to compute gray value
      $grayColor = $grayR | $grayG | $grayB;
      // set the pixel color
      imagesetpixel ($sourceImage, $x, $y, $grayColor);
      imagecolorallocate ($sourceImage, $gray, $gray, $gray);
    }
  }
  // copy pixel values to new file buffer
  $destinationImage = ImageCreateTrueColor($img_width, $img_height);
  imagecopy($destinationImage, $sourceImage, 0, 0, 0, 0, $img_width, $img_height);
  // create file on disk
  imagejpeg($destinationImage, $destinationFileName);
  
  // destroy temp image buffers
  imagedestroy($destinationImage);  
  imagedestroy($sourceImage);
?>
Copy-paste, replace the file names on the top and there you go (picture files must be in same folder as this script. If not, you will have to do your own file management).

grayscale conversion is built-in with imagefilter(). 
<?php
   /* other code */
   $image = imagecreatefromjpeg('some.jpg');
   imagefilter($image, IMG_FILTER_GRAYSCALE);
   /* other code (ie save) */
   imagedestroy($image);
   /* other code */
?>
you could create the sepia effect by the following:
<?php
   /* other code */
   $image = imagecreatefromjpeg('some.jpg');
   imagefilter($image, IMG_FILTER_GRAYSCALE);
   imagefilter($image, IMG_FILTER_COLORIZE, 112, 66, 20);
   //Wikipedia RGB definition of sepia
   /* other code (ie save) */
   imagedestroy($image);
   /* other code */
?>

I've changed a little switch251's code and here we have sephia effect
<?php
  // replace with your files
  $originalFileName  = $filename;
  $destinationFileName = "2".$filename;
  
  // create a copy of the original image
  // works with jpg images
  // fell free to adapt to other formats ;)
  $fullPath = explode(".",$originalFileName);
  $lastIndex = sizeof($fullPath) - 1;
  $extension = $fullPath[$lastIndex];
  if (preg_match("/jpg|jpeg|JPG|JPEG/", $extension))
  {
    $sourceImage = imagecreatefromjpeg($originalFileName);
  }
  // get image dimensions
  $img_width = imageSX($sourceImage);
  $img_height = imageSY($sourceImage);
  // convert to grayscale
  // note: this will NOT affect your original image, unless
  // originalFileName and destinationFileName are the same
  for ($y = 0; $y <$img_height; $y++) 
  { 
    for ($x = 0; $x <$img_width; $x++) 
    { 
      $rgb = imagecolorat($sourceImage, $x, $y);
      $red  = ($rgb >> 16) & 0xFF;
      $green = ($rgb >> 8) & 0xFF;
      $blue = $rgb & 0xFF;
     //sephia
      $red2 = min($red*.393 + $green*.769 + $blue*.189,255);
      $green2 = min($red*.349 + $green*.686 + $blue*.168,255);
      $blue2 = min($red*.272 + $green*.534 + $blue*.131,255);
      // shift gray level to the left
      
      $grayR = $red2 << 16;  // R: red
      $grayG = $green2 << 8 ;  // G: green
      $grayB = $blue2;     // B: blue
      
      // OR operation to compute gray value
      $grayColor = $grayR | $grayG | $grayB;
      
      // set the pixel color
      imagesetpixel ($sourceImage, $x, $y, $grayColor);
      imagecolorallocate ($sourceImage, $gray, $gray, $gray);
    }
  }
  // copy pixel values to new file buffer
  $destinationImage = ImageCreateTrueColor($img_width, $img_height);
  imagecopy($destinationImage, $sourceImage, 0, 0, 0, 0, $img_width, $img_height);
  // create file on disk
  imagejpeg($destinationImage, $destinationFileName);
  
  // destroy temp image buffers
  imagedestroy($destinationImage);  
  imagedestroy($sourceImage);
?>

in addition to code_couturier - try this formula to calculate gray-value (luminance) in his "more exact" way:
$gray = round(.299*$red + .587*$green + .114*$blue);

# very fast way to generate a grayscal-
# image from a true color image
#...
# --- quick grayscale image
for ($y = 0; $y <$img_height; $y++) { 
 for ($x = 0; $x <$img_width; $x++) { 
 # here we extract the green from 
 # the pixel at x,y , to use it as gray value
 $gray = (ImageColorAt($image, $x, $y) >> 8) & 0xFF;
 # a more exact way would be this:
 # $rgb = ImageColorAt($image, $x, $y);
 # $red = ($rgb >> 16) & 0xFF;
 # $green = (trgb >> 8) & 0xFF;
 # $blue = $rgb & 0xFF;
 # $gray = (int)(($red+$green+$blue)/4); 
 # and here we set the new pixel/color
 imagesetpixel ($image, $x, $y, 
 ImageColorAllocate ($image, $gray,$gray,$gray));
 }
}
 
# ...

This function don't work properly for me on trucolerimages (have not tried yet for other types) it jsut produce a part-grayscale image, and some color get mesed up.
I found a workaround here:
http://www.phpbuilder.com/columns/cash20030526.php3?page=2
[quote]
Advanced Image Editing Under the GD Library
Colorizing
Colorizing images is fairly easy to do. The easiest way to colorize an image is fairly simple to grasp. Create an image of the same dimensions and fill that image with the color you want to change it to. This new image is then placed on top of the older image, giving it a colorized look.
<?php 
function imagecolorize(&$im,&$col,$pct) { 
  // Get the image's width 
  $im_w = imagesx($im); 
  // Get the image's height 
  $im_h = imagesy($im); 
  // Set a pixel with the color, so we can get it easily 
  $setpixel = imagesetpixel($im,$im_w,0,$col); 
  // Get the color 
  $index = imagecolorat($im,$im_w,0); 
  // Find the color in the index 
  $rgb = imagecolorsforindex($im,$index); 
  // Get the red value 
  $r = $rgb["red"]; 
  // Get the green value 
  $g = $rgb["green"]; 
  // Get the blue value 
  $b = $rgb["blue"]; 
  // Create the layover 
  $layover = imagecreate($im_w,$im_h); 
  // Allocate the color on this image 
  $color = imagecolorallocate($layover,$r,$g,$b); 
  // Fill the image with the new color (this really isn't needed) 
  $fill = imagefill($layover,0,0,$color); 
  // Merge the layover on top of the older image 
  $merge = imagecopymerge($im,$layover,0,0,0,0,$im_w,$im_h,$pct); 
  imagedestroy($layover); // Destroy the layover 
} 
?> 
If we use a blue layover RGB(0,0,255), we get this result:
[/quote]
if you use black or gray, its not perfekt, but better than nothing ;)