opencv-image-diff

Compare images using OpenCV library through its Java bindings

Compile

Change OpenCV file jar location in file build.properties according to your OpenCV installation path. Default is /usr/local/share/OpenCV/java/opencv-300.jar.

$ ant

This will comiple both executable and library jars. Look at dist folder.

Executable

One can run executable jar with the following command:

$ java -cp /usr/local/share/OpenCV/java/opencv-300.jar:dist/opencv-image-diff-bin-0.1-201602201436.jar \
    -Djava.library.path=/usr/local/share/OpenCV/java/ \
    org.nebur.opencv.java.OpenCVImageDiff \
    -dd res/visu.jpg res/visu_1.jpg

Change paths /usr/local/share/OpenCV/java/[...] according to your OpenCV installation path.

Options

Issue -h or --help to see command line arguments.

Usage: [OPTIONS]... IMAGE1 IMAGE2

OPTIONS can be the following:

• -a, --algorithm - OpenCV algorithm to be used. Following OpenCV algorithms are supported:
  • matchResult (default)
    • IMAGE1 = template
    • IMAGE2 = test
  • compareHist
    • IMAGE1 = base
    • IMAGE2 = test
• -m, --method - OpenCV method of the specified algorithm. Available methods for each algorithm:
  • matchResult:
    • CV_TM_SQDIFF
    • CV_TM_SQDIFF_NORMED
    • CV_TM_CCORR
    • CV_TM_CCORR_NORMED (default)
    • CV_TM_CCOEFF
    • CV_TM_CCOEFF_NORMED
  • compareHist:
    • CV_COMP_CORREL (default)
    • CV_COMP_CHISQR
    • CV_COMP_INTERSECT
    • CV_COMP_BHATTACHARYYA
• -t, --threshold - Threshold used in diff comparisons
• -e, --epsilon - Epsilon used in diff comparisons: (threshold - diff) > epsilon
• -dd, --display-diff - Display on a graphical window the diff result
• -mr, --merge-rects - Merge error rectangles when display diff is enabled
• -v, --verbose - Improve output log

Library

@TODO: doc library jar

OpenCV

In order to better understand returned values and else take a look at:

• Template Matching: http://docs.opencv.org/3.0.0/de/da9/tutorial_template_matching.html
• Histogram Comparison: http://docs.opencv.org/3.0.0/d8/dc8/tutorial_histogram_comparison.html