ImageMagick: Command-line Tools: Identify

The identify program describes the format and characteristics of one or more image files. It also reports if an image is incomplete or corrupt. The information returned includes the image number, the file name, the width and height of the image, whether the image is colormapped or not, the number of colors in the image, the number of bytes in the image, the format of the image (JPEG, PNM, etc.), and finally the number of seconds it took to read and process the image. Many more attributes are available with the verbose option. See Command Line Processing for advice on how to structure your identify command or see below for example usages of the command.

Example Usage

We list a few examples of the identify command here to illustrate its usefulness and ease of use. To get started, lets identify an image in the JPEG format:

  identify rose.jpg
  rose.jpg JPEG 640x480 DirectClass 87kb 0.050u 0:01

Next, we look at the same image in greater detail:

  identify -verbose rose.jpg
  Image: rose.jpg
    Format: JPEG (Joint Photographic Experts Group JFIF format)
    Geometry: 640x480
    Class: DirectClass
    Type: TrueColor
    Endianess: Undefined
    Colorspace: RGB
    Depth: 8 bits
    Channel depth:
      Red: 8-bits
      Green: 8-bits
      Blue: 8-bits
    Channel statistics:
      Red:
        Min: 0 (0)
        Max: 255 (1)
        Mean: 228.152 (0.894713)
        Standard deviation: 70.3632 (0.275934)
      Green:
        Min: 1 (0.00392157)
        Max: 255 (1)
        Mean: 229.041 (0.898198)
        Standard deviation: 62.6714 (0.24577)
      Blue:
        Min: 0 (0)
        Max: 255 (1)
        Mean: 232.299 (0.910975)
        Standard deviation: 55.2762 (0.216769)
    Colors: 12314
    Rendering-intent: Undefined
    Resolution: 72x72
    Units: PixelsPerInch
    Filesize: 87kb
    Interlace: None
    Background Color: white
    Border Color: #DFDFDF
    Matte Color: grey74
    Dispose: Undefined
    Iterations: 0
    Compression: JPEG
    Quality: 100
    Orientation: Undefined
    JPEG-Colorspace: 2
    JPEG-Sampling-factors: 2x2,1x1,1x1
    Signature: e20b287cfed4f152572bdfb89f7f5f677d869c504620e8b1a9b3aa1d9d834785
    Tainted: False
    User Time: 0.040u
    Elapsed Time: 0:01
    Version: ImageMagick 6.2.0 02/20/05 Q16 http://www.imagemagick.org

The dimensions of depth a raw image must be specified on the command line:

  identify -depth 8 -size 640x480 image.raw
  rose.rgb RGB 70x46 DirectClass 9kb 0.000u 0:01

You can find additional examples of using identify in Graphics from the Command Line. Further discussion is available in More Graphics from the Command Line and Examples of ImageMagick Usage.

Option Summary

The identify command recognizes these options. Click on an option to get more details about how that option works.

Option	Description
-authenticate value	decrypt image with this password
-channel type	apply option to select image channels
-crop geometry	crop the image
-debug events	display copious debugging information
-define format:option	define one or more image format options
-density geometry	horizontal and vertical density of the image
-depth value	image depth
-extract geometry	extract area from image
-format string	output formatted image characteristics
-help	print program options
-interlace type	type of image interlacing scheme
-limit type value	pixel cache resource limit
-list type	Color, Configure, Delegate, Format, Magic, Module, Resource, or Type
-log format	format of debugging information
-matte	store matte channel if the image has one
-monitor	monitor progress
-quiet	suppress all error or warning messages
-sampling-factor geometry	horizontal and vertical sampling factor
-set attribute value	set an image attribute
-size geometry	width and height of image
-strip	strip image of all profiles and comments
-units type	the units of image resolution
-verbose	print detailed information about the image
-version	print version information
-virtual-pixel method	access method for pixels outside the boundaries of the image