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; ???}}?>php转换bmp图片格式为jpg格式
原文地址：http://www.cnblogs.com/fxlttkl/p/7779041.html