Error executing class with parameter by main

I'm trying to compile my code through cmd by passing the image parameter (name and format). But it returns me this error.

java ImageSplit tileset.png

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 1
        at ImageSplit.main(ImageSplit.java:33)

The code is this:

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;

public class ImageSplit {

    private static int width = 0;
    private static int height = 0;
    private static final int tileSize = 16;

    private BufferedImage readImage(String caminho) {

        BufferedImage bi = null;
        try {
            bi = ImageIO.read(new File(
                    getClass().getResource(caminho).getFile()));
        } catch (IOException e) {
            e.printStackTrace();
        }
        return bi;
    }

    public static void main(String[] args) {

        ImageSplit imageSplit = new ImageSplit();
        BufferedImage image = null; 
        if(args.length < 1) {
            System.out.println("Informe o parametro da imagem.");
            return;
        }
        image = imageSplit.readImage(args[1]);
        width = image.getWidth() / tileSize; // Col, tile
        height = image.getHeight() / tileSize; // Row, tile
        BufferedImage[] subImages = new BufferedImage[width * height];
        for(int i=0; i<height; i++) {
            for(int j=0; j<width; j++) {
                subImages[i * width + j] = image.getSubimage(j * 16, i * 16, tileSize, tileSize);
            }
        }
        for(int i=0; i<subImages.length; i++) {
            try {
                ImageIO.write(subImages[i], "tile" + i + ".png", new File("./Tiles"));
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

And the image is in the same folder as the class.