se solucionó el problema por el cual no mostraba las imágenes

jweb-e001/WebContent/WEB-INF/web.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" version="3.1">
+  <display-name>jweb-e001</display-name>
+  <welcome-file-list>
+    <welcome-file>index.html</welcome-file>
+    <welcome-file>index.htm</welcome-file>
+    <welcome-file>index.jsp</welcome-file>
+    <welcome-file>default.html</welcome-file>
+    <welcome-file>default.htm</welcome-file>
+    <welcome-file>default.jsp</welcome-file>
+  </welcome-file-list>
+  <servlet-mapping>   
+    <servlet-name>default</servlet-name>
+    <url-pattern>*.html</url-pattern>
+</servlet-mapping>
+<servlet-mapping>
+    <servlet-name>default</servlet-name>
+    <url-pattern>*.jpg</url-pattern>
+</servlet-mapping>
+<servlet-mapping>
+ <servlet-name>default</servlet-name>
+    <url-pattern>*.png</url-pattern>
+</servlet-mapping>
+<servlet-mapping>
+    <servlet-name>default</servlet-name>
+    <url-pattern>*.css</url-pattern>
+</servlet-mapping>
+<servlet-mapping>
+    <servlet-name>default</servlet-name>
+    <url-pattern>*.js</url-pattern>
+</servlet-mapping>
+  
+  
+</web-app>
\ No newline at end of file

jweb-e001/src/servlets/Poker.java

@@ -31,7 +31,7 @@ public class Poker extends HttpServlet {
 		String palo = request.getParameter("palo").toLowerCase();
 		String valor = request.getParameter("valor").toLowerCase();
 		
-		String rutaImagen = this.getServletContext().getRealPath("/imagenesCartas/"+valor+palo+".png");
+		String rutaImagen = "imagenesCartas/"+valor+palo+".png";
 		System.out.println(rutaImagen);
 		
 		PrintWriter respuesta = response.getWriter();