note 79910 added to function.imagewbmp
| From: | andre at bynetworld dot com | Date: | Wed, 19 Dec 2007 13:31:43 +0000 |
| Subject: | note 79910 added to function.imagewbmp | ||
| Groups: | php.notes | ||
| Request: | Send a blank email to php-notes+get-133777@lists.php.net to get a copy of this message | ||
In the previous note by -> lukeross at sys3175 dot co dot uk <- there is a coding error in the
for() loops. After correcting the error, I found that this function did a great job of converting
color images to 2 colors.
The following is the corrected function code:
function ImageColorFloydSteinberg($dst_img, $src_img) {
ImageColorAllocate($dst_img, 0,0,0);
ImageColorAllocate($dst_img, 255,255,255);
$isx = ImageSX($src_img);
$isy = ImageSY($src_img);
$grey_img = ImageCreate($isx, $isy);
for ($a = 0; $a <= 255; $a++) ImageColorAllocate($grey_img, $a,$a,$a);
$isx -= 1; // To correct pixel count in source image width starting from 0
$isy -= 1; // Correcting pixel count in source image height starting from 0
for($x = 0; $x <= $isx; $x++) {
for($y = 0; $y <= $isy; $y++) {
$color = ImageColorsForIndex($src_img, ImageColorAt($src_img, $x, $y));
$greyscale = .299 * $color["red"] + .587 * $color["green"] + .114 *
$color["blue"];
ImageSetPixel($grey_img, $x, $y, ImageColorClosest($grey_img, $greyscale, $greyscale,
$greyscale));
}
}
for($x = 0; $x <= $isx; $x++) {
for($y = 0; $y <= $isy; $y++) {
$color = ImageColorsForIndex($grey_img, ImageColorAt($grey_img, $x, $y));
if ($color["red"] > 128) {
ImageSetPixel($dst_img, $x, $y, ImageColorClosest($dst_img,255,255,255));
$err = $color["red"] - 255;
} else {
ImageSetPixel($dst_img, $x, $y, ImageColorClosest($dst_img,0,0,0));
$err = $color["red"];
}
if ($x != $isx) {
$color2 = ImageColorsForIndex($grey_img, ImageColorAt($grey_img, $x+1, $y));
$newgrey = $color2["red"] + $err * 7 / 16;
ImageSetPixel($grey_img, $x+1, $y, ImageColorClosest($grey_img,$newgrey, $newgrey,
$newgrey));
}
if ($x != 0) {
$color2 = ImageColorsForIndex($grey_img, ImageColorAt($grey_img, $x-1, $y));
$newgrey = $color2["red"] + $err * 3 / 16;
ImageSetPixel($grey_img, $x-1, $y, ImageColorClosest($grey_img,$newgrey, $newgrey,
$newgrey));
}
if ($y != $isy) {
$color2 = ImageColorsForIndex($grey_img, ImageColorAt($grey_img, $x, $y+1));
$newgrey = $color2["red"] + $err * 5 / 16;
ImageSetPixel($grey_img, $x, $y+1, ImageColorClosest($grey_img,$newgrey, $newgrey,
$newgrey));
}
if ($x != $isx && $y != $isy) {
$color2 = ImageColorsForIndex($grey_img, ImageColorAt($grey_img, $x+1, $y+1));
$newgrey = $color2["red"] + $err / 16;
ImageSetPixel($grey_img, $x+1, $y+1, ImageColorClosest($grey_img,$newgrey, $newgrey,
$newgrey));
}
}
}
imagedestroy($grey_img);
}
----
Server IP: 69.147.83.197
Probable Submitter: 99.240.194.65
----
Manual Page -- http://www.php.net/manual/en/function.imagewbmp.php
Edit -- https://master.php.net/note/edit/79910
Del: integrated -- https://master.php.net/note/delete/79910/integrated
Del: useless -- https://master.php.net/note/delete/79910/useless
Del: bad code -- https://master.php.net/note/delete/79910/bad+code
Del: spam -- https://master.php.net/note/delete/79910/spam
Del: non-english -- https://master.php.net/note/delete/79910/non-english
Del: in docs -- https://master.php.net/note/delete/79910/in+docs
Del: other reasons-- https://master.php.net/note/delete/79910
Reject -- https://master.php.net/note/reject/79910
Search -- https://master.php.net/manage/user-notes.php