A command-line tool that combines two pictures into a single, larger one, and opens a GUI window (provided by the Python Imaging Library) or an external image viewer.

You could use it with a version control tool, e.g.

bzr diff *.png --using=imgdiff


bzr diff *.png --using='imgdiff --eog -H'


pip install imgdiff or download it from PyPI.


Run imgdiff --help to see this help message:

Usage: imgdiff [options] image1 image2

Compare two images side-by-side

  -h, --help            show this help message and exit
  -o OUTFILE            write the combined image to a file
  --viewer=COMMAND      use an external image viewer (default: builtin)
  --eog                 use Eye of Gnome (same as --viewer eog)
  --grace=SECONDS       seconds to wait before removing temporary file when
                        using an external viewer (default: 1.0)
  -H, --highlight       highlight differences (EXPERIMENTAL)
  -S, --smart-highlight
                        highlight differences in a smarter way (EXPERIMENTAL)
  --opacity=OPACITY     minimum opacity for highlighting (default 64)
  --timeout=TIMEOUT     skip highlighting if it takes too long (default: 10
  --auto                pick orientation automatically (default)
  --lr, --left-right    force orientation to left-and-right
  --tb, --top-bottom    force orientation to top-and-bottom
  --bgcolor=RGB         background color (default: fff)
  --sepcolor=RGB        separator line color (default: ccc)
  --spacing=N           spacing between images (default: 3 pixels)
  --border=N            border around images (default: 0 pixels)

Output Examples

First example:

imgdiff set1/42.png set3/
example #1

Here the images are wide and short, so imgdiff decided to put them one above the other.

Same example, with highlighting enabled:

imgdiff set1/42.png set3/ -H
example #2

You can see that it doesn't work very well, although it can produce nice results in simpler cases:

imgdiff set1/42.png set2/ -H
example #3

Support and Development

The source code can be found in this Git repository:

To check it out, use git clone

Report bugs at


1.7.0 (2016-09-17)

  • Clarify the help message for the --opacity option.
  • Add Python 3.5 support.
  • Drop Python 2.6 and 3.2 support.

1.6.0 (2014-12-01)

  • Add Python 3 support.
  • Make the --timeout option actually work.
  • Drop the --selftest option. Add a real test suite with 100% coverage (which actually means little, since these are smoke tests that don't inspect the results for correctness.)

1.5.0 (2013-08-11)

  • Suppress progress output if stderr is not a terminal.
  • Make it possible to abort --highligh/--smart-highlight logic by pressing ^C.
  • Abort --highlight/--smart-highlight logic if it takes longer than 10 seconds (timeout changeable with --timeout; use 0 to turn it off).

1.4.1 (2013-08-09)

  • Depend on Pillow instead of PIL.
  • Moved to GitHub.

1.4.0 (2010-12-19)

  • Accepts directory names: imgdiff dir1/img.png dir2/.
  • Centers images relative to each other if they have different width/height.
  • Automatic orientation (--auto) uses the golden ratio (1:1.618) as its goal for desired height:width instead of a 1:1 square.
  • New experimental options: --highlight (-H) and --smart-highlight (-S). These highlight areas that are different and fade out areas that are similar. Or at least they try.
  • New options for tweaking the output: --bgcolor, --sepcolor, --spacing, --border, --opacity.
  • New option: --eog as alias for --viewer eog, but shorter. Guess what desktop environment I'm using. ;-)
  • A puny "test suite", runnable with imgdiff --selftest.
  • Better source code documentation via docstrings.

1.3.0 (2010-12-18)

  • First public release. Options supported: -o, --viewer, --grace, --auto, --lr, --tb, --help.