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Цветовая гамма в php

Содержание
  1. imagecolorset
  2. Parameters
  3. Return Values
  4. Changelog
  5. Examples
  6. See Also
  7. User Contributed Notes 10 notes
  8. PHP: генерирование оттенков
  9. Напишем две элементарные функции, которые будет делать нам оттенки.

imagecolorset

This sets the specified index in the palette to the specified color. This is useful for creating flood-fill-like effects in palleted images without the overhead of performing the actual flood-fill.

Parameters

A GdImage object, returned by one of the image creation functions, such as imagecreatetruecolor() .

Return Values

The function returns null on success, or false on failure.

Changelog

Version Description
8.0.0 image expects a GdImage instance now; previously, a valid gd resource was expected.

Examples

Example #1 imagecolorset() example

// Create a 300×100 image
$im = imagecreate ( 300 , 100 );

// Set the background to be red
imagecolorallocate ( $im , 255 , 0 , 0 );

// Get the color index for the background
$bg = imagecolorat ( $im , 0 , 0 );

// Set the backgrund to be blue
imagecolorset ( $im , $bg , 0 , 0 , 255 );

// Output the image to the browser
header ( ‘Content-Type: image/png’ );

imagepng ( $im );
imagedestroy ( $im );
?>

See Also

User Contributed Notes 10 notes

If you want to convert a Color image to Grayscale without creating a blotchy image, use this color calculation:
function imagetograyscale ( $im )
if ( imageistruecolor ( $im )) imagetruecolortopalette ( $im , false , 256 );
>

for ( $c = 0 ; $c < imagecolorstotal ( $im ); $c ++) $col = imagecolorsforindex ( $im , $c );
$gray = round ( 0.299 * $col [ ‘red’ ] + 0.587 * $col [ ‘green’ ] + 0.114 * $col [ ‘blue’ ]);
imagecolorset ( $im , $c , $gray , $gray , $gray );
>
>
?>

I’ve been looking for a simple function which «colorizes» an image, without any success . it looks like a lot of people mean something different with «colorizing» an image, because actually colorzing means multiplying the old color’s grayscale with the new color. So a white pixel would become 100% of the colorize-to-color and a black pixel would stay black (I know I can’t explain well . I hope you understood, otherwise take a look at the example below the functions’ code).

for ( $x = 0 ; $x < $numColors ; $x ++) list( $r , $g , $b ) = array_values ( imageColorsForIndex ( $img , $x ));

// calculate grayscale in percent
$grayscale = ( $r + $g + $b ) / 3 / 0xff ;

imageColorSet ( $img , $x ,
$grayscale * $rgb [ 0 ],
$grayscale * $rgb [ 1 ],
$grayscale * $rgb [ 2 ]
);
>

return true ;
>
?>

Example of usage:
$color = array( 0xff , 0xaa , 0x2a ); // color to convert to
$url = ‘http://sundog.net/images/uploads/1_google_logo.jpg’ ;
$img = imageCreateFromJpeg ( $url );

image_colorize ( $img , $color );

header ( ‘Content-type: image/gif’ );
imageGif ( $img );
exit;
?>

Enjoy

this is helpful if you would like to implement a color theme system in your website. try it out
Davide Candiloro Italy

function colorize ($pngpath, $r, $g, $b)
/*
REQUIRES: $pngpath to be a valid path of a greyscale PNG-8 image with 64 colors palette
$r, $g, $b to be integers in the range 0..255
EFFECTS: returns the png image colorized with the color represented by $r, $g, $b.
*/
header(«Content-type: image/png»);
$im = imagecreatefrompng(«images/table.png»);

imagetruecolortopalette($im, FALSE, 256);

for ($c = 0; $c < 64; $c++)< /*64 is the number of colors in the PNG-8 palette*/
$col = imagecolorsforindex($im, $c);
imagecolorset ( $im, $c, $r*$col[‘red’]/256, $g*$col[‘green’]/256, $b*$col[‘blue’]/256); /*replaces original greyscale palette with a colorized one*/
>

here’s a function to greyscale an image even from a truecolor source (jpeg or png).

slightly poor quality, but very fast.

function imagegreyscale(&$img, $dither=1) <
if (!($t = imagecolorstotal($img))) $t = 256;
imagetruecolortopalette($img, $dither, $t);
>
for ($c = 0; $c < $t; $c++) <
$col = imagecolorsforindex($img, $c);
$min = min($col[‘red’],$col[‘green’],$col[‘blue’]);
$max = max($col[‘red’],$col[‘green’],$col[‘blue’]);
$i = ($max+$min)/2;
imagecolorset($img, $c, $i, $i, $i);
>
>

If you are creating a palette image from scratch you have to use imagecolorallocate() for each index before you can use imagecolorset() on it.

Here is a function to colorize a picture gradient style.

All you have to do is to pass an img-object and an array of colors.

$arr = array(‘#000000’, ‘#990000’, ‘#00FFFF’, ‘#FFFFDD’);
colorize ($img, $arr);

function colorize ( $imgdata , $palette )
imageTrueColorToPalette ( $imgdata , false , 0xFF );
$l = count ( $palette )- 1 ;
$i = imagecolorstotal ( $imgdata );
while ( $i —)
list( $r , $g , $b ) = array_values ( imageColorsForIndex ( $imgdata , $i ));

$grayscale = ( $r * .3 + $g * .59 + $b * .11 ) / 0xFF ;

$tbase = str_replace ( «#» , » , $palette [ $pos ]);
$baseR = hexdec ( substr ( $tbase , 0 , 2 ));
$baseG = hexdec ( substr ( $tbase , 2 , 2 ));
$baseB = hexdec ( substr ( $tbase , 4 , 2 ));

$tmix = str_replace ( «#» , » , $palette [ $pos + 1 ]);
$mixR = hexdec ( substr ( $tmix , 0 , 2 ));
$mixG = hexdec ( substr ( $tmix , 2 , 2 ));
$mixB = hexdec ( substr ( $tmix , 4 , 2 ));

$resR = $baseR +( $mixR — $baseR )* $perc ;
$resG = $baseG +( $mixG — $baseG )* $perc ;
$resB = $baseB +( $mixB — $baseB )* $perc ;

imagecolorset ( $imgdata , $i , $resR , $resG , $resB );
>
>
?>

This function change colors of an image with ranges 0>100 for each primary color:

int ImageSelectiveColor (int im, int red, int green, int blue)

im is image pointer
red, green and blue are ranges 0->100

function ImageSelectiveColor($im,$red,$green,$blue)
<
for($i=0;$i <
$col=ImageColorsForIndex($im,$i);
$red_set=$red/100*$col[‘red’];
$green_set=$green/100*$col[‘green’];
$blue_set=$blue/100*$col[‘blue’];
if($red_set>255)$red_set=255;
if($green_set>255)$green_set=255;
if($blue_set>255)$blue_set=255;
imagecolorset($im,$i,$red_set,$green_set,$blue_set);

I had the same problem as heavyraptor2 so i made this function.
function imagecolorize ( $im , $endcolor ) //funcion takes image and turns black into $endcolor, white to white and
//everything in between in corresponding gradient
//$endcolor should be 6 char html color

//make sure it has usable palette
if ( imageistruecolor ( $im )) imagetruecolortopalette ( $im , false , 256 );
>

//first make it gray to be sure of even results (thanks moxleystratton.com)
//comment this loop if you want the output based on, for example,
//the red channel (for this take a look at the $gray-var in the last loop)
for ( $c = 0 ; $c < imagecolorstotal ( $im ); $c ++) $col = imagecolorsforindex ( $im , $c );
$gray = round ( 0.299 * $col [ ‘red’ ] + 0.587 * $col [ ‘green’ ] + 0.114 * $col [ ‘blue’ ]);
imagecolorset ( $im , $c , $gray , $gray , $gray );
>

//determine end-colors in hexdec
$EndcolorRGB [ ‘r’ ] = hexdec ( substr ( $endcolor , 0 , 2 ));
$EndcolorRGB [ ‘g’ ] = hexdec ( substr ( $endcolor , 2 , 2 ));
$EndcolorRGB [ ‘b’ ] = hexdec ( substr ( $endcolor , 4 , 2 ));

//determine gradient-delta’s
$stepR = ( 255 — $EndcolorRGB [ ‘r’ ])/ 255.0 ;
$stepG = ( 255 — $EndcolorRGB [ ‘g’ ])/ 255.0 ;
$stepB = ( 255 — $EndcolorRGB [ ‘b’ ])/ 255.0 ;

//aColor contains the 256 gradations between endcolor(i=0) and white(i=255)
$aColor = array();
for ( $i = 0 ; $i $aColor [ $i ][ ‘r’ ] = $EndcolorRGB [ ‘r’ ] + ( $i * $stepR );
$aColor [ $i ][ ‘g’ ] = $EndcolorRGB [ ‘g’ ] + ( $i * $stepG );
$aColor [ $i ][ ‘b’ ] = $EndcolorRGB [ ‘b’ ] + ( $i * $stepB );
>

//for every color-index we now replace $gray-values for $aColor
for ( $c = 0 ; $c < imagecolorstotal ( $im ); $c ++)$currentColorRGB = imagecolorsforindex ( $im , $c );
$gray = $currentColorRGB [ ‘red’ ]; //image is grayscale, so red,green and blue
// should be equal. We use this number as key of aColor
imagecolorset ( $im , $c ,(int) $aColor [ $gray ][ ‘r’ ], (int) $aColor [ $gray ][ ‘g’ ], (int) $aColor [ $gray ][ ‘b’ ]);
>
> ?>

Here is a function to turn an image into pure black and white

function imagepurebw ( $img , $amount = 383 ) $total = imagecolorstotal ( $img );
for ( $i = 0 ; $i < $total ; $i ++ ) $index = imagecolorsforindex ( $img , $i );
array_pop ( $index );
$color = ( array_sum ( $index ) > $amount ) ? 255 : 0 ;
imagecolorset ( $img , $i , $color , $color , $color );
>
>

here’s a simple function to greyscale an image.

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