|
|
|
|
Bookmark this on Delicious
Share on Facebook
 Slashdot It!
Digg imagecolorsforindex
Get the colors for an index
(PHP 4, PHP 5)
Parameters
Return ValuesReturns an associative array with red, green, blue and alpha keys that contain the appropriate values for the specified color index. ExamplesExample 993. imagecolorsforindex() example<?phpThe above example will output something similar to: Array
See Also
Code Examples / Notes » imagecolorsforindexadspeed.com
To correct m4551 at abasoft dot it example: ImageTrueColorToPalette($im,1,$t); might give less colors than $t, so the for loop should call "$i<ImageColorsTotal($im)" instead of "$i<$t" just to be sure, or you'll get the warning: Color index [0-9] out of range admin
this is a sepia filter using microsoft's definition <?php function imagesepia( $img ) { $total = imagecolorstotal( $img ); for ( $i = 0; $i < $total; $i++ ) { $index = imagecolorsforindex( $img, $i ); $red = ( $index["red"] * 0.393 + $index["green"] * 0.769 + $index["blue"] * 0.189 ) / 1.351; $green = ( $index["red"] * 0.349 + $index["green"] * 0.686 + $index["blue"] * 0.168 ) / 1.203; $blue = ( $index["red"] * 0.272 + $index["green"] * 0.534 + $index["blue"] * 0.131 ) / 2.140; imagecolorset( $img, $i, $red, $green, $blue ); } } ?> strozek a deas harvard edu
Regarding m4551's method of conversion -- the actual CCIR-approved RGB-to-grayscale conversion is as follows: grayscale component = 0.2125*R + 0.7154*G + 0.0721*B (cf. CCIR Recommendation 709 for modern monitors) slepichev
If you would like to change the intensity or lightness level of a specific color, you will need to convert the color format from RGB to HSL. following function convert RGB array(red,green,blue) to HSL array(hue, saturation, lightness) <?php /** * Convert RGB colors array into HSL array * * @param array $ RGB colors set * @return array HSL set */ function rgb2hsl($rgb){ $clrR = ($rgb[0] / 255); $clrG = ($rgb[1] / 255); $clrB = ($rgb[2] / 255); $clrMin = min($clrR, $clrG, $clrB); $clrMax = max($clrR, $clrG, $clrB); $deltaMax = $clrMax - $clrMin; $L = ($clrMax + $clrMin) / 2; if (0 == $deltaMax){ $H = 0; $S = 0; } else{ if (0.5 > $L){ $S = $deltaMax / ($clrMax + $clrMin); } else{ $S = $deltaMax / (2 - $clrMax - $clrMin); } $deltaR = ((($clrMax - $clrR) / 6) + ($deltaMax / 2)) / $deltaMax; $deltaG = ((($clrMax - $clrG) / 6) + ($deltaMax / 2)) / $deltaMax; $deltaB = ((($clrMax - $clrB) / 6) + ($deltaMax / 2)) / $deltaMax; if ($clrR == $clrMax){ $H = $deltaB - $deltaG; } else if ($clrG == $clrMax){ $H = (1 / 3) + $deltaR - $deltaB; } else if ($clrB == $clrMax){ $H = (2 / 3) + $deltaG - $deltaR; } if (0 > $H) $H += 1; if (1 < $H) $H -= 1; } return array($H, $S, $L); } ?> m4551
here's a function to greyscale an image even from a truecolor source (jpeg or png). slightly poor quality, but very fast... function imagegreyscale(&$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, $i); } } tim
Here's a better grayscale, sepia, and general tinting function. This function is better because: 1) Works with true color images (the other sepia code didn't). 2) Provides a more gooder grayscale conversion (yes, I said "more gooder"). The other grayscale code used imagetruecolortopalette, which just doesn't work well for grayscale conversion. 3) The other sepia code was really colorful, a little too much for my taste. This function allows you to optionally set the tinting of the grayscale to anything you wish. 4) Single function for grayscale, sepia, and any other tinting you can dream up. Here's some examples: imagegrayscaletint ($img); // Grayscale, no tinting imagegrayscaletint ($img,304,242,209); // What I use for sepia imagegrayscaletint ($img,0,0,255); // A berry blue image The RGB values for tinting are normally from 0 to 255. But, you can use values larger than 255 to lighten and "burn" the image. The sepia example above does this a little, the below example provides a better example of lightening the image and burning the light areas out a little: imagegrayscaletint ($img,400,400,400); // Lighten image imagegrayscaletint ($img,127,127,127); // Darken image <? function imagegrayscaletint (&$img, $tint_r = 255, $tint_g = 255, $tint_b = 255) { $width = imagesx($img); $height = imagesy($img); $dest = imagecreate ($width, $height); for ($i=0; $i<256; $i++) imagecolorallocate ($dest, $i, $i, $i); imagecopyresized ($dest, $img, 0, 0, 0, 0, $width, $height, $width, $height); for ($i = 0; $i < 256; $i++) imagecolorset ($dest, $i, min($i * abs($tint_r) / 255, 255), min($i * abs($tint_g) / 255, 255), min($i * abs($tint_b) / 255, 255)); $img = imagecreate ($width, $height); imagecopy ($img, $dest, 0, 0, 0, 0, $width, $height); imagedestroy ($dest); } ?> |
Change Language
gd_info getimagesize image_type_to_extension image_type_to_mime_type image2wbmp imagealphablending imageantialias imagearc imagechar imagecharup imagecolorallocate imagecolorallocatealpha imagecolorat imagecolorclosest imagecolorclosestalpha imagecolorclosesthwb imagecolordeallocate imagecolorexact imagecolorexactalpha imagecolormatch imagecolorresolve imagecolorresolvealpha imagecolorset imagecolorsforindex imagecolorstotal imagecolortransparent imageconvolution imagecopy imagecopymerge imagecopymergegray imagecopyresampled imagecopyresized imagecreate imagecreatefromgd2 imagecreatefromgd2part imagecreatefromgd imagecreatefromgif imagecreatefromjpeg imagecreatefrompng imagecreatefromstring imagecreatefromwbmp imagecreatefromxbm imagecreatefromxpm imagecreatetruecolor imagedashedline imagedestroy imageellipse imagefill imagefilledarc imagefilledellipse imagefilledpolygon imagefilledrectangle imagefilltoborder imagefilter imagefontheight imagefontwidth imageftbbox imagefttext imagegammacorrect imagegd2 imagegd imagegif imagegrabscreen imagegrabwindow imageinterlace imageistruecolor imagejpeg imagelayereffect imageline imageloadfont imagepalettecopy imagepng imagepolygon imagepsbbox imagepsencodefont imagepsextendfont imagepsfreefont imagepsloadfont imagepsslantfont imagepstext imagerectangle imagerotate imagesavealpha imagesetbrush imagesetpixel imagesetstyle imagesetthickness imagesettile imagestring imagestringup imagesx imagesy imagetruecolortopalette imagettfbbox imagettftext imagetypes imagewbmp imagexbm iptcembed iptcparse jpeg2wbmp png2wbmp |
