How to read pixel values from Mat and Bitmap images on Android

Retrieving the value of RGBA 0..255 from Bitmap can be done using Bitmap#getPixel(x,y), for example:

//cf.https://stackoverflow.com/a/26960189/3501958
int color=bitmap.getPixel(x,y);

intred=Color.red(color);
int green=Color.green(color);
int blue=Color.blue(color);
int alpha=Color.alpha(color);

Log.d(TAG, String.format(
        "(R,G,B,A)=(%3d,%3d,%3d,%3d),red,green,blue,alpha
));

I'm not familiar with Mat format files, but once you convert them to Bitmap, the rest is the same.In any Android program, the image files (whether PNG or JPEG) are basically operated in Bitmap.

I haven't checked, but I found a code snippet called to convert Mat to Bitmap in OpenCV.