标识格式字符串

自定义标识格式字符串

When identifying an image, you may want to use a custom formatting string instead of using -verbose, which is quite slow. You can use your own formatting string when using gm().identify(format, callback). For example,

gm('img.png').format(function (err, format) {

})

// is equivalent to

gm('img.png').identify('%m', function (err, format) {

})

since %m is the format option for getting the image file format.