php如何将bmp转jpg格式

php bmp转jpg的方法：首先打开“php.ini”文件；然后开启gd扩展库；最后使用“changeBMPtoJPG”等方法将bmp的文件转换成jpg格式即可。

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php转换bmp图片格式为jpg格式

进行图片格式转换前，先输出phpinfo()查看php库信息，查看gd扩展库是否开启，若未开启，打开php.ini文件，用查找工具找到extension=php_gd2.dll，把extension=php_gd2.dll 前面的【;】，就可以了

这里转换成为jpg格式需要JPEG Support支持,png需要 PNG Support支持，对应的先检查自己转的格式是否支持

imagejpeg()函数失败也许是你的文件夹权限问题，得多注意

可以先用function_exist()函数ImageCreateFromBMP检查是否存在，下例中的ImageCreateFromBMP_private用来代替ImageCreateFromBMP方法

示例代码如下：

<?php 
$srcFile ='test.bmp';//需要转换的图片
$info = getimagesize($srcFile);    
$srcFileExt=$info['mime'];
//判断是否是bmp格式
if($srcFileExt=='image/x-ms-bmp'){
    $result = changeBMPtoJPG($srcFile);
    if($result){
        echo $result;
    }else{
        echo "转换失败!";
    }
}else{
    echo "该图片不是bmp格式";
} 
exit;

function ImageCreateFromBMP_private($filename) {
    if (!$f1 = fopen($filename, "rb"))
        return false;

    $FILE = unpack("vfile_type/Vfile_size/Vreserved/Vbitmap_offset", fread($f1, 14));
    if ($FILE['file_type'] != 19778)
        return false;

    $BMP = unpack('Vheader_size/Vwidth/Vheight/vplanes/vbits_per_pixel' .
        '/Vcompression/Vsize_bitmap/Vhoriz_resolution' .
        '/Vvert_resolution/Vcolors_used/Vcolors_important', fread($f1, 40));
    $BMP['colors'] = pow(2, $BMP['bits_per_pixel']);
    if ($BMP['size_bitmap'] == 0)
        $BMP['size_bitmap'] = $FILE['file_size'] - $FILE['bitmap_offset'];
    $BMP['bytes_per_pixel'] = $BMP['bits_per_pixel'] / 8;
    $BMP['bytes_per_pixel2'] = ceil($BMP['bytes_per_pixel']);
    $BMP['decal'] = ($BMP['width'] * $BMP['bytes_per_pixel'] / 4);
    $BMP['decal'] -= floor($BMP['width'] * $BMP['bytes_per_pixel'] / 4);
    $BMP['decal'] = 4 - (4 * $BMP['decal']);
    if ($BMP['decal'] == 4)
        $BMP['decal'] = 0;

    $PALETTE = array();
    if ($BMP['colors'] < 16777216) {
        $PALETTE = unpack('V' . $BMP['colors'], fread($f1, $BMP['colors'] * 4));
    }

    $IMG = fread($f1, $BMP['size_bitmap']);
    $VIDE = chr(0);

    $res = imagecreatetruecolor($BMP['width'], $BMP['height']);
    $P = 0;
    $Y = $BMP['height'] - 1;
    while ($Y >= 0) {
        $X = 0;
        while ($X < $BMP['width']) {
            switch ($BMP['bits_per_pixel']) {
                case 32:
                    $COLOR = unpack("V", substr($IMG, $P, 3) . $VIDE);
                    break;
                case 24:
                    $COLOR = unpack("V", substr($IMG, $P, 3) . $VIDE);
                    break;
                case 16:
                    $COLOR = unpack("n", substr($IMG, $P, 2));
                    $COLOR[1] = $PALETTE[$COLOR[1]   1];
                    break;
                case 8:
                    $COLOR = unpack("n", $VIDE . substr($IMG, $P, 1));
                    $COLOR[1] = $PALETTE[$COLOR[1]   1];
                    break;
                case 4:
                    $COLOR = unpack("n", $VIDE . substr($IMG, floor($P), 1));
                    if (($P * 2) % 2 == 0)
                        $COLOR[1] = ($COLOR[1] >> 4);
                    else
                        $COLOR[1] = ($COLOR[1] & 0x0F);
                    $COLOR[1] = $PALETTE[$COLOR[1]   1];
                    break;
                case 1:
                    $COLOR = unpack("n", $VIDE . substr($IMG, floor($P), 1));
                    if (($P * 8) % 8 == 0)
                        $COLOR[1] = $COLOR[1] >> 7;
                    elseif (($P * 8) % 8 == 1)
                        $COLOR[1] = ($COLOR[1] & 0x40) >> 6;
                    elseif (($P * 8) % 8 == 2)
                        $COLOR[1] = ($COLOR[1] & 0x20) >> 5;
                    elseif (($P * 8) % 8 == 3)
                        $COLOR[1] = ($COLOR[1] & 0x10) >> 4;
                    elseif (($P * 8) % 8 == 4)
                        $COLOR[1] = ($COLOR[1] & 0x8) >> 3;
                    elseif (($P * 8) % 8 == 5)
                        $COLOR[1] = ($COLOR[1] & 0x4) >> 2;
                    elseif (($P * 8) % 8 == 6)
                        $COLOR[1] = ($COLOR[1] & 0x2) >> 1;
                    elseif (($P * 8) % 8 == 7)
                        $COLOR[1] = ($COLOR[1] & 0x1);
                    $COLOR[1] = $PALETTE[$COLOR[1]   1];
                    break;
                default:
                    return false;
                    break;
            }

            imagesetpixel($res, $X, $Y, $COLOR[1]);
            $X  ;
            $P  = $BMP['bytes_per_pixel'];
        }
        $Y--;
        $P =$BMP['decal'];
    }
    fclose($f1);
    return $res;
}

function changeBMPtoJPG($srcPathName){
    $srcFile=$srcPathName;  
    $dstFile = str_replace('.bmp', '.jpg', $srcPathName);
    $photoSize = GetImageSize($srcFile);  
    $pw = $photoSize[0];  
    $ph = $photoSize[1];
    $dstImage = ImageCreateTrueColor($pw, $ph);  
    $white = imagecolorallocate($dstImage, 255, 255, 255);
    //用 $white 颜色填充图像
    imagefill( $dstImage, 0, 0, $white);
    //读取图片  
    $srcImage = ImageCreateFromBMP_private($srcFile); 
    //合拼图片  

    imagecopyresampled($dstImage, $srcImage, 0, 0, 0, 0, $pw, $ph, $pw, $ph);  
    $judge = imagejpeg($dstImage, $dstFile, 90);  
    imagedestroy($dstImage);
    if($judge){
        return $dstFile;
    }else{
        return false;
    }
}

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