imagetypes
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);
}
imagewbmp
(PHP 4 >= 4.0.1, PHP 5)
imagewbmp — Afișează imaginea în navigator sau în fișier
Descrierea
bool imagewbmp
( resource
$image
[, string $filename
[, int $foreground
]] )
imagewbmp() outputs or save a WBMP
version of the given image.
Parametri
-
image -
O resursă - imagine, întoarsă de una din funcțiile de creare a imaginilor, cum ar fi imagecreatetruecolor().
-
filename -
Calea unde va fi salvat fișierul. Dacă nu este stabilită sau este
NULL, atunci fluxul imaginii va fi afișat direct. -
foreground -
You can set the foreground color with this parameter by setting an identifier obtained from imagecolorallocate(). The default foreground color is black.
Valorile întoarse
Întoarce valoarea TRUE în cazul
succesului sau FALSE în cazul eșecului.
Exemple
Example #1 Outputting a WBMP image
<?php
// Create a blank image and add some text
$im = imagecreatetruecolor(120, 20);
$text_color = imagecolorallocate($im, 233, 14, 91);
imagestring($im, 1, 5, 5, 'A Simple Text String', $text_color);
// Set the content type header - in this case image/vnd.wap.wbmp
// Hint: see image_type_to_mime_type() for content-types
header('Content-Type: image/vnd.wap.wbmp');
// Output the image
imagewbmp($im);
// Free up memory
imagedestroy($im);
?>
Example #2 Saving the WBMP image
<?php
// Create a blank image and add some text
$im = imagecreatetruecolor(120, 20);
$text_color = imagecolorallocate($im, 233, 14, 91);
imagestring($im, 1, 5, 5, 'A Simple Text String', $text_color);
// Save the image
imagewbmp($im, 'simpletext.wbmp');
// Free up memory
imagedestroy($im);
?>
Example #3 Outputting the image with a different foreground
<?php
// Create a blank image and add some text
$im = imagecreatetruecolor(120, 20);
$text_color = imagecolorallocate($im, 233, 14, 91);
imagestring($im, 1, 5, 5, 'A Simple Text String', $text_color);
// Set the content type header - in this case image/vnd.wap.wbmp
// Hint: see image_type_to_mime_type() for content-types
header('Content-Type: image/vnd.wap.wbmp');
// Set a replacement foreground color
$foreground_color = imagecolorallocate($im, 255, 0, 0);
imagewbmp($im, NULL, $foreground_color);
// Free up memory
imagedestroy($im);
?>
Note
Notă:
WBMP support is only available if PHP was compiled against GD-1.8 or later.
Vedeți de asemenea
- image2wbmp() - Afișează imaginea în navigator sau în fișier
- imagepng() - Output a PNG image to either the browser or a file
- imagegif() - Afișează imaginea în navigator sau în fișier
- imagejpeg() - Afișează imaginea în navigator sau în fișier
- imagetypes() - Return the image types supported by this PHP build
add a note
User Contributed Notes
imagewbmp
andre at bynetworld dot com
19-Dec-2007 05:31
lukeross at sys3175 dot co dot uk
28-Feb-2002 01:57
As has been commented before, GD doesnt do a very good translation to 2-colours, especially for photos. The following routine converts to two colours, I believe using error diffusion (the algorithm's nicked off news). It's slow, but just about adequate for small images and low load. I suspect it can be made much more efficient :-)
function ImageColorFloydSteinberg($dst_img, $src_img) {
ImageColorAllocate($dst_img, 0,0,0);
ImageColorAllocate($dst_img, 255,255,255);
$grey_img = ImageCreate(ImageSX($src_img), ImageSY($src_img));
for ($a = 0; $a <= 255; $a++) ImageColorAllocate($grey_img, $a,$a,$a);
for($x = 0; $x <= ImageSX($src_img); $x++) {
for($y = 0; $y <= ImageSY($src_img); $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; $x <= ImageSX($src_img); $x++) {
for($y = 0; $y <= ImageSY($src_img); $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 != ImageSx($src_img)) {
$color2 = ImageColorsForIndex($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 != ImageSy($src_img)) {
$color2 = ImageColorsForIndex($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 != ImageSx($src_img) && $y != ImageSy($src_img)) {
$color2 = ImageColorsForIndex($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);
}
To output your WBMP, use
ImageWBMP($final_img, "", ImageColorClosest(255,255,255));