imagewbmp

(PHP 4 >= 4.0.1, PHP 5, PHP 7, PHP 8)

imagewbmp — 以 WBMP 格式将图像输出到浏览器或文件

说明

imagewbmp ( resource $image , string $filename = ? , int $foreground = ? ) : bool

imagewbmp() 从 image 图像创建一个名为 filename 的 WBMP 文件。image 参数是 imagecreatetruecolor() 的返回值。

filename 参数是可选项，如果省略，则直接将原图像流输出。通过用 header() 发送 image/vnd.wap.wbmp 的 Content-type，可以创建直接输出 WBMP 图像的 PHP 脚本。

Note:
WBMP 支持仅能用于 PHP 编译时加入了 GD-1.8 或更高版本时。

用可选的 foreground 参数可以设定前景色，用 imagecolorallocate() 函数返回的颜色标识符。默认前景色是黑色。

参见 image2wbmp()，imagepng()，imagegif()，imagejpeg() 和 imagetypes()。

User Contributed Notes

andre at bynetworld dot com 19-Dec-2007 05:31


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);

}

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));