j < nimages in function 'cv::histPrepareImages for package ai.certifai.solution.image_processing.HistogramEqualization.java

[KianYang-Lee]

Describe the bug When run, this error occurred.

opencv-4.3.0\modules\imgproc\src\histogram.cpp:160: error: (-215:Assertion failed) j < nimages in function 'cv::histPrepareImages

Screenshots

Additional context Also noticed the outdated import line. Will open a branch to fix this when schedule is less packed.

[jacklynlxq]

It seems to be the problem with the dimension / number of channels.

Not sure if it'd work on your machine but I managed to eliminate the error by changing this line private IntPointer channels = new IntPointer(3); to int[] channels_arr = new int[]{0, 1, 2}; private IntPointer channels = new IntPointer(channels_arr);

in the Histogram1DJava.java file

I am not sure what is the reason behind it but you can look into the source code and maybe there's a better workaround:

• https://github.com/bytedeco/javacpp/blob/f8e91858655cebbc673f9c07303ad324b813427f/src/main/java/org/bytedeco/javacpp/IntPointer.java#L62
• https://github.com/opencv/opencv/blob/3a062eed5b961d05ae03423fec78a4980e488d9a/modules/imgproc/src/histogram.cpp#L160 (looks like the error was produced from here)

Ref: https://github.com/bytedeco/javacv-examples/blob/master/OpenCV_Cookbook/src/test/java/opencv_cookbook/CalcHistTest.java

[KianYang-Lee]

Thanks! It works wonderfully! will update it in the patch