Image Format and Characteristics
Example Usage • Option Summary
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 70x46 70x46+0+0 8-bit sRGB 2.36KB 0.000u 0:00.000
By default, identify provides the following output:
Filename[frame #] image-format widthxheight page-widthxpage-height+x-offset+y-offset colorspace user-time elapsed-timeNext, we look at the same image in greater detail:
-> identify -verbose rose.jpg
Image: rose.jpg
Format: JPEG (Joint Photographic Experts Group JFIF format)
Mime type: image/jpeg
Class: DirectClass
Geometry: 70x46+0+0
Units: Undefined
Type: TrueColor
Endianess: Undefined
Colorspace: sRGB
Depth: 8-bit
Channel depth:
red: 8-bit
green: 8-bit
blue: 8-bit
Channel statistics:
Pixels: 3220
Red:
min: 35 (0.137255)
max: 255 (1)
mean: 145.57 (0.570865)
standard deviation: 67.2976 (0.263912)
kurtosis: -1.37971
skewness: 0.0942169
entropy: 0.974889
Green:
min: 33 (0.129412)
max: 255 (1)
mean: 89.2193 (0.349879)
standard deviation: 52.0803 (0.204236)
kurtosis: 2.70722
skewness: 1.82562
entropy: 0.877139
Blue:
min: 11 (0.0431373)
max: 255 (1)
mean: 80.3742 (0.315193)
standard deviation: 53.8536 (0.21119)
kurtosis: 2.90978
skewness: 1.92617
entropy: 0.866692
Image statistics:
Overall:
min: 11 (0.0431373)
max: 255 (1)
mean: 105.055 (0.411979)
standard deviation: 58.1422 (0.228008)
kurtosis: 1.25759
skewness: 1.4277
entropy: 0.90624
Rendering intent: Perceptual
Gamma: 0.454545
Chromaticity:
red primary: (0.64,0.33,0.03)
green primary: (0.3,0.6,0.1)
blue primary: (0.15,0.06,0.79)
white point: (0.3127,0.329,0.3583)
Background color: white
Border color: srgb(223,223,223)
Matte color: grey74
Transparent color: black
Interlace: None
Intensity: Undefined
Compose: Over
Page geometry: 70x46+0+0
Dispose: Undefined
Iterations: 0
Compression: JPEG
Quality: 92
Orientation: Undefined
Properties:
date:create: 2014-11-09T09:00:35-05:00
date:modify: 2014-11-09T09:00:35-05:00
jpeg:colorspace: 2
jpeg:sampling-factor: 2x2,1x1,1x1
signature: 22a99838bd5594250f706d1d9383b2830f439fcbaf1455cbe2f7f59a4deb065a
Artifacts:
filename: rose.jpg
verbose: true
Tainted: False
Filesize: 2.36KB
Number pixels: 3.22K
Pixels per second: 3.22EB
User time: 0.000u
Elapsed time: 0:01.000
Version: ImageMagick Q16 https://imagemagick.org
Note, the image signature is generated from the pixel components, not the ima ge metadata.
To get the print size in inches of an image at 72 DPI, use:
-> identify -format "%[fx:w/72] by %[fx:h/72] inches" document.png
8.5 x 11 inches
The depth and dimensions of a raw image must be specified on the command line:
-> identify -depth 8 -size 640x480 image.raw
image.raw RGB 640x480 sRGB 9kb 0.000u 0:01
Here we display the image texture features, moments, perceptual hash, and the number of unique colors in the image:
-> identify -verbose -features 1 -moments -unique image.png
Here is a special define that outputs the location of the minimum or maximum pixel of the image:
identify -precision 5 -define identify:locate=maximum -define identify:limit=3 image.png
You can find additional examples of using identify in 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 |
|---|---|
| -alpha | on, activate, off, deactivate, set, opaque, copy", transparent, extract, background, or shape the alpha channel |
| -antialias | remove pixel-aliasing |
| -authenticate value | decrypt image with this password |
| -auto-orient | automagically orient image |
| -channel type | apply option to select image channels |
| -clip | clip along the first path from the 8BIM profile |
| -clip-mask filename | associate clip mask with the image |
| -clip-path id | clip along a named path from the 8BIM profile |
| -colorspace type | set image colorspace |
| -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 |
| -endian type | endianness (MSB or LSB) of the image |
| -extract geometry | extract area from image |
| -features distance | analyze image features (e.g. contract, correlations, etc.). |
| -format string | output formatted image characteristics |
| -gamma value | level of gamma correction |
| -grayscale method | convert image to grayscale |
| -help | print program options |
| -interlace type | type of image interlacing scheme |
| -interpolate method | pixel color interpolation method |
| -limit type value | pixel cache resource limit |
| -list type | Color, Configure, Delegate, Format, Magic, Module, Resource, or Type |
| -log format | format of debugging information |
| -mask filename | associate a mask with the image |
| -moments | display image moments and perceptual hash. |
| -monitor | monitor progress |
| -negate | replace each pixel with its complementary color |
| -ping | by default, efficiently determine certain image characteristics by only reading the requisite image metadata. To accurately identify all the image metadata and pixel characteristics, use +ping. |
| -precision value | set the maximum number of significant digits to be printed |
| -quiet | suppress all warning messages |
| -regard-warnings | pay attention to warning messages. |
| -respect-parentheses | settings remain in effect until parenthesis boundary. |
| -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 |
| -unique | display image the number of unique colors in the image. |
| -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 |