Java image library - turn grid image into array

Question

If I have an image of a table of boxes, with some coloured in, is there an image processing library that can help me turn this into an array?

Thanks

Answer 1

You can use a thresholding function to binarize the image into dark/light pixels so dark pixels are 0 and light ones are 1.

Then you would want to remove image artifacts using dilation and erosion functions to remove noise (all these are well defined on Wikipedia).

Finally if you know where the boxes are, you can just get the value in the center of each box to determine the array value, or possibly use an area near the center and take the prevailing value (i.e. more 0's is a filled in square, more 1's is and empty square).

If you are scanning these boxes and there is a lot of variation in the position of the boxes, you will have to perform some level of image registration using known points, or fiducials.

As far as what tools to use to do this, I'd recommend first trying this manually using a tool like ImageJ, which has a UI and can also be used programatically since it is written all in Java.

Other good libraries for this include OpenCV and the Java Advanced Imaging API.

Your results will definitely vary depending on the input images and how consistenly lit and positioned they are.

The best way to see how it will do for your data is to try applying these processing steps manually to see where your threshold value should be, how much dilating/eroding you need to get consistent results.