我正在寻找一种快速获取图像高度和宽度的方法.它应该至少处理JPG,PNG和TIFF,但越多越好.我强调快速,因为我的图像非常大(高达250 MB)并且使用ImageMagick获得大小需要太长时间,identify因为它显然首先将图像作为整体读取.
最好是,我寻找一种在Ruby中运行良好的方法,甚至在Rails 3中.
我知道理论的东西(各种图像格式,它们的标题和它们的差异,等等).实际上,我要求某种类型的库可以通过相当通用的方式解决我的问题.
我刚刚找到http://imagesize.rubyforge.org看起来很有希望虽然发展似乎已经死了.
ypn*_*nos 188
该file命令打印多种图像格式的尺寸(例如PNG,GIF,JPEG;最新版本也是PPM,WEBP),并且只读取标题.
该identify命令(来自ImageMagick)为各种图像打印大量图像信息.它似乎限制自己阅读标题部分(见评论).它也有一个统一的输出,file可悲的是缺乏.
exiv2为您提供多种格式的尺寸,包括JPEG,TIFF,PNG,GIF,WEBP,即使没有EXIF标题.目前还不清楚它是否读取了整个数据.有关所有支持的图像格式,请参阅exiv2的联机帮助页.
head -n1 将为您提供PPM,PGM格式的尺寸.
在网络上流行的格式,都exiv2和identify会做的工作.根据用例,您可能需要编写自己的脚本来组合/解析多个工具的输出.
ajr*_*eal 32
我不确定你是否安装了php,但这个PHP函数非常方便
php -r "print_r(getimagesize('http://www.google.com/images/logos/ps_logo2.png'));"
Jam*_* L. 15
您可以使用ImageMagick的识别功能.这是你在bash中的表现(注意$ 0是图像的路径):
width=$(identify -format "%w" "$0")> /dev/null
height=$(identify -format "%h" "$0")> /dev/null
这也隐藏了任何潜在的错误消息.现代实现identify只读取标题,而不是整个图像,所以它很快.不知道它与其他方法相比如何.
这里有两种格式PNG和JPG.
我的代码来自我设计的类,您可以根据自己的需要进行编辑.
请使用PHP检查这些函数/方法:
public function ByteStreamImageString($ByteStream,&$Formato,&$Alto,&$Ancho) {
$Alto = 0;
$Ancho = 0;
$Formato = -1;
$this->HexImageString = "Error";
if (ord($ByteStream[0])==137 && ord($ByteStream[1])==80 && ord($ByteStream[2])==78){
$Formato = 1; //PNG
$Alto = $this->Byte2PosInt($ByteStream[22],$ByteStream[23]);
$Ancho = $this->Byte2PosInt($ByteStream[18],$ByteStream[19]);
}
if (ord($ByteStream[0])==255 && ord($ByteStream[1])==216
&& ord($ByteStream[2])==255 && ord($ByteStream[3])==224){
$Formato = 2; //JPG
$PosJPG = 2;
while ($PosJPG<strlen($ByteStream)){
if (sprintf("%02X%02X", ord($ByteStream[$PosJPG+0]),ord($ByteStream[$PosJPG+1]))=="FFC0"){
$Alto = $this->Byte2PosInt($ByteStream[$PosJPG+5],$ByteStream[$PosJPG+6]);
$Ancho = $this->Byte2PosInt($ByteStream[$PosJPG+7],$ByteStream[$PosJPG+8]);
}
$PosJPG = $PosJPG+2+$this->Byte2PosInt($ByteStream[$PosJPG+2],$ByteStream[$PosJPG+3]);
}
}
if ($Formato > 0){
$this->HexImageString = "";
$Salto = 0;
for ($i=0;$i < strlen($ByteStream); $i++){
$Salto++;
$this->HexImageString .= sprintf("%02x", ord($ByteStream[$i]));
if ($Salto==64){
$this->HexImageString .= "\n";
$Salto = 0;
}
}
}
}
private function Byte2PosInt($Byte08,$Byte00) {
return ((ord($Byte08) & 0xFF) << 8)|((ord($Byte00) & 0xFF) << 0);
}
使用PHP代码:
$iFormato = NULL;//Format PNG or JPG
$iAlto = NULL; //High
$iAncho = NULL;//Wide
ByteStreamImageString($ImageJPG,$iFormato,$iAlto,$iAncho);//The Dimensions will stored in iFormato,iAlto,iAncho
现在这些函数/方法使用JAVA:
private void ByteStreamImageString(byte[] ByteStream,int[] Frmt,int[] High,int[] Wide) {
High[0] = 0;
Wide[0] = 0;
Frmt[0] = -1;
this.HexImageString = "Error";
if ((int)(ByteStream[0]&0xFF)==137 && (int)(ByteStream[1]&0xFF)==80 &&(int)(ByteStream[2]&0xFF)==78){
Frmt[0] = 1; //PNG
High[0] = this.Byte2PosInt(ByteStream[22],ByteStream[23]);
Wide[0] = this.Byte2PosInt(ByteStream[18],ByteStream[19]);
}
if ((int)(ByteStream[0]&0xFF)==255 && (int)(ByteStream[1]&0xFF)==216
&&(int)(ByteStream[2]&0xFF)==255 && (int)(ByteStream[3]&0xFF)==224){
Frmt[0] = 2; //JPG
int PosJPG = 2;
while (PosJPG<ByteStream.length){
if (String.format("%02X%02X", ByteStream[PosJPG+0],ByteStream[PosJPG+1]).equals("FFC0")){
High[0] = this.Byte2PosInt(ByteStream[PosJPG+5],ByteStream[PosJPG+6]);
Wide[0] = this.Byte2PosInt(ByteStream[PosJPG+7],ByteStream[PosJPG+8]);
}
PosJPG = PosJPG+2+this.Byte2PosInt(ByteStream[PosJPG+2],ByteStream[PosJPG+3]);
}
}
if (Frmt[0] > 0){
this.HexImageString = "";
int Salto = 0;
for (int i=0;i < ByteStream.length; i++){
Salto++;
this.HexImageString += String.format("%02x", ByteStream[i]);
if (Salto==64){
this.HexImageString += "\n";
Salto = 0;
}
}
}
}
private Integer Byte2PosInt(byte Byte08, byte Byte00) {
return new Integer (((Byte08 & 0xFF) << 8)|((Byte00 & 0xFF) << 0));
}
使用Java代码:
int[] iFormato = new int[1]; //Format PNG or JPG
int[] iAlto = new int[1]; //High
int[] iAncho = new int[1]; //Wide
ByteStreamImageString(ImageJPG,iFormato,iAlto,iAncho); //The Dimensions will stored in iFormato[0],iAlto[0],iAncho[0]
小智 0
如果图像中有 EXIF 信息，则只需读取 EXIF 标头即可。