Methods for downscaling a bitmap to powers of 2 sizes ( https://medium.com/@petrakeas/alias-free-resize-with-renderscript-5bf15a86ce3 )

successiveResize.java

public class resizeUtils {  
  
    public static Bitmap successiveResize(Bitmap src, int resizeNum) {
        int srcWidth = src.getWidth();
        int srcHeight = src.getHeight();
        Bitmap output = src;
        for (int i = 0; i < resizeNum; i++) {
            srcWidth /= 2;
            srcHeight /= 2;
            Bitmap temp = Bitmap.createScaledBitmap(output, srcWidth, srcHeight, true);
            if (i != 0) { // don't recycle the src bitmap
                output.recycle();
            }
            output = temp;
        }
        return output;
    }

    public static Bitmap successiveResizeRS(RenderScript rs, Bitmap src, int resizeNum) {
        int srcWidth = src.getWidth();
        int srcHeight = src.getHeight();
        Bitmap.Config config = src.getConfig();

        Allocation srcAllocation = Allocation.createFromBitmap(rs, src);
        ScriptIntrinsicResize resizeScript = ScriptIntrinsicResize.create(rs);

        Allocation outAllocation = null;
        for (int i = 0; i < resizeNum; i++) {
            srcWidth /= 2;
            srcHeight /= 2;

            Type t = Type.createXY(rs, srcAllocation.getElement(), srcWidth, srcHeight);
            outAllocation = Allocation.createTyped(rs, t);
            resizeScript.setInput(srcAllocation);
            resizeScript.forEach_bicubic(outAllocation);

            srcAllocation.destroy();
            srcAllocation = outAllocation;
        }

        Bitmap output = Bitmap.createBitmap(srcWidth, srcHeight, config);
        outAllocation.copyTo(output);

        resizeScript.destroy();
        outAllocation.destroy();

        return output;
    }
}