Read dimensions of BMP image

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

public class ReadBMPImageDimensions {
    public static void main(String[] args) {
        String fileName = "logo.bmp";
        int headerSize = 54;
        int width = 0, height = 0;

        try (FileInputStream fileStream = new FileInputStream(fileName)) {
            byte[] headerData = new byte[headerSize];
            fileStream.read(headerData, 0, headerSize);

            if (headerData[0] == 'B' && headerData[1] == 'M') {
                width = bytesToInt(headerData, 18, 22);
                height = bytesToInt(headerData, 22, 26);
                System.out.println(width + "x" + height);
            } else {
                System.out.println("Not a valid BMP file.");
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static int bytesToInt(byte[] bytes, int start, int end) {
        int result = 0;
        for (int i = end - 1; i >= start; i--) {
            result = (result << 8) | (bytes[i] & 0xFF);
        }
        return result;
    }
}