bjorn

bjorn

Image comparison tool for Bjorn

bjorn allow the users (like Bjorn) to compare images that are provided as a list in a csv file

Installation

LATEST RELEASE

Download the appropriate release package as per you operating system. Supported operating systems are:

• MacOS (Darwin)
• Windows
• Linux

Unpack the downloaded archive in you local directory to install the bjorn cli tool.

Usage

Usage:
  bjorn [command]

Available Commands:
  diff        compare images listed in a csv file
  help        Help about any command

bjorn diff

compare images listed in a csv file.

bjorn diff [flags]

Options

  -f, --file string   CSV file to read image list
  -h, --help          help for diff
  -o, --out string    Output file location
      --alsologtostderr                  log to standard error as well as files
      --config string                    config file (default is $HOME/.bjorn.yaml)
  -h, --help                             help for bjorn
      --log_backtrace_at traceLocation   when logging hits line file:N, emit a stack trace (default :0)
      --log_dir string                   If non-empty, write log files in this directory
      --logtostderr                      log to standard error instead of files
      --stderrthreshold severity         logs at or above this threshold go to stderr (default 2)
  -v, --v Level                          log level for V logs
      --vmodule moduleSpec               comma-separated list of pattern=N settings for file-filtered logging

Development

Image Comparison

Bjorn uses a simple pixel based approach to image comparison. Each pixel of the 2 images being compared using the RGB values of each pixel. The Score is calculated by summing up the difference in RGB values for each pixel and using this value to get the ratio of different pixels to total pixels in the images.

Limitations of current approach:

• It assumes the images are of the same size. Scaled versions of the same image will be considered different.
• Comparing same images in different formats (png, jpg, gif) can produce a score of ~0.01-0.02. The comparison algorithm uses a threshold of 0.01, below which images are considered similar

Further Development

The comparison algorithm is defined as the Compare() function in the pair package. This function may be extended to improve the comparison algorithm. Possible improvements include:

• Improve comparison algorithm to consider scaled images.
• Add ability to define multiple comparison algorithm and flags to select each.
• Add command to compare 2 images separately (eg bjorn diff images img1 img2).