Use the below entries for your web.xml
<context-param>
<param-name>crystal_image_uri</param-name>
<param-value>crystalreportviewers</param-value>
</context-param>
<context-param>
<param-name>crystal_image_use_relative</param-name>
<param-value>webapp</param-value>
</context-param>
<servlet>
<servlet-name>CrystalReportViewerServlet</servlet-name>
<servlet-class>com.crystaldecisions.report.web.viewer.CrystalReportViewerServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>CrystalReportViewerServlet</servlet-name>
<url-pattern>/CrystalReportViewerHandler</url-pattern>
</servlet-mapping>
Thanks,
Prithvi