Images-diff

Description

Compare images and report the differences.

Given images a.jpeg, b.jpeg, and c.jpeg, the program performs the following comparisons:

• a.jpeg and b.jpeg
• b.jpeg and c.jpeg

The differences can be computed using MSE (mean error squared) or SSIM (structural similarity index measure) as the metric.

Requirements

• Node.js (>=20).
• ImageMagick (>=7.1), when MSE is used as the metric.
• FFmpeg (>=6.1), when SSIM is used as the metric.

Installation

0. npm clean-install --production

Configuration

Create a configuration file with the name .env. The configuration file controls the following:

• MAGICK_PATH: Path of ImageMagick.
  • If magick (for UNIX/ Linux system) or magick.exe is in the PATH environment variable, it is not necessary to specify the full path, the executable name itself is sufficient.
• FFMPEG_PATH: Path of FFmpeg.
  • If ffmpeg (for UNIX/ Linux system) or ffmpeg.exe is in the PATH environment variable, it is not necessary to specify the full path, the executable name itself is sufficient.
• METRIC: Comparison metric. Acceptable values are mse and ssim.
• DIFF_THRESHOLD: Difference threhsold. If the differene is beyond the threshold, the comparison pair is considered as abnormal.
• ABNORMAL_IMAGES_DIRECTORY: The directory to be created for abnormal images. If specified, the directory will be created under the input directory.
• Set all of the following to crop to the area to be inspected:
  • CROP_WIDTH: The width of a cropped image.
  • CROP_HEIGHT: The height of a cropped image.
  • CROP_OFFSET_X: The offset from the left of the original image.
  • CROP_OFFSET_Y: The offset from the top of the originam image.

An example, .env.template, is provided as a reference.

Examples

Assume the directory /path/to/images contains some images for comparisons and using SSIM as the metric, execute:

node index.js /path/to/images

The output will be similar to the following:

[OKAY] 01.png, 02.png: 1
[OKAY] 02.png, 03.png: 1
[OKAY] 03.png, 04.png: 1
[WARN] 04.png, 05.png: 0.250075

The output shows that:

• The difference between 01.png and 02.png is 0 and within threshold.
• The difference between 02.png and 03.png is 0 and within threshold.
• The difference between 03.png and 04.png is 0 and within threshold.
• The difference between 04.png and 05.png is 0.250075 and below threshold.

If ABNORMAL_IMAGES_DIRECTORY is specified, 04.png and 05.png will be copied to the directory.

License

The BSD 3-Clause License