How do I get image dimensions with ImageMagick?

Use identify with a format string: identify -format '%wx%h' image.jpg. It reads only the header, so it is fast across large numbers of files.

How do I read EXIF data with ImageMagick?

identify -format '%[EXIF:*]' photo.jpg prints every EXIF tag. You can also request individual tags such as %[EXIF:DateTimeOriginal].

How do I count the pages in a PDF with ImageMagick?

identify -format '%n\n' document.pdf returns the number of images inside the file, which works for GIF frames as well.

Is identify a separate command from convert?

Yes. On ImageMagick 6 it is its own binary. On ImageMagick 7 you invoke it as magick identify.

ImageMagick identify — read image information

Use ImageMagick identify to read dimensions, format, colour depth, EXIF and page count. Includes the format string tokens and scripting-friendly one-liners.

identify reads only the file header rather than decoding the whole image, so it is cheap enough to run across thousands of files. On ImageMagick 7 it is magick identify; on IM6 it is identify.

Quick summary

identify photo.jpg

photo.jpg JPEG 1600x900 1600x900+0+0 8-bit sRGB 62790B 0.000u 0:00.000

The second geometry is the page geometry — for a cropped image it reveals the virtual canvas that +repage would remove.

Just the fields you want

identify -format '%f %wx%h %m %b\n' *.jpg

This is the form you want in scripts — one clean line per file, no parsing required.

Useful format tokens

Token	Meaning
`%f`	Filename
`%w` / `%h`	Width / height in pixels
`%m`	Format (JPEG, PNG…)
`%b`	File size
`%n`	Number of frames or pages
`%Q`	JPEG quality the file was saved at
`%[colorspace]`	Colour space
`%z`	Bit depth
`%A`	Whether an alpha channel is present
`%[EXIF:*]`	Every EXIF tag

Read EXIF without another tool

identify -format '%[EXIF:*]' photo.jpg
identify -format '%[EXIF:DateTimeOriginal] %[EXIF:Model]\n' photo.jpg

Count pages in a PDF or frames in a GIF

identify -format '%n\n' document.pdf
identify -format '%n\n' animation.gif

Everything about a file

identify -verbose photo.jpg

Long. Pipe it through grep or head. It includes the colour histogram, which is genuinely useful for working out how many distinct colours a graphic actually uses before quantising it.

Recover the JPEG quality a file was saved at

identify -format '%Q\n' photo.jpg

ImageMagick estimates this from the quantisation tables. Re-encoding at a higher number than the original does not restore quality — it just makes a bigger file. Match or go slightly below.

Find images that break a rule

# everything wider than 3000px
identify -format '%w %f\n' *.jpg | awk '$1 > 3000 {print $2}'

# everything that is not sRGB
identify -format '%[colorspace] %f\n' *.jpg | grep -v '^sRGB'

Check a file is actually what its extension claims

identify -format '%m %f\n' *.png | grep -v '^PNG'

Handy before a batch job, and a cheap sanity check on user uploads — though it is not a security control on its own.