PHP : Function Reference : Image Functions : imagewbmp PHP Examples Tutorials References

There is a hidden third parameter in the ImageWbmp function that serves as a threshold-holder. When using the function as in: ImageWbmp ($im, "test.wbmp"); it generates a warning: Warning: imagewbmp: invalid threshold value '-1'. It must be between 0 and 255 in blablabla It does generate the image though but for a WML app. it cannot be used since the warning is laden with HTML-tags. To prevent the warning use the following example: ImageWbmp ($im, "test.wbmp", 0); The warning is no longer generated.

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));

imagewbmp

Output image to browser or file (PHP 4 >= 4.0.1, PHP 5)
bool imagewbmp ( resource image [, string filename [, int foreground]] )

Code Examples / Notes » imagewbmp

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imagewbmp

Output image to browser or file (PHP 4 >= 4.0.1, PHP 5) bool imagewbmp ( resource image [, string filename [, int foreground]] )

Code Examples / Notes » imagewbmp

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Output image to browser or file (PHP 4 >= 4.0.1, PHP 5)
bool imagewbmp ( resource image [, string filename [, int foreground]] )