Bug 190981 The image id of image in different pages are the same
The id of image generated by the same report item (such as chart) are the same, thought the image contents are in different pages.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/Image.java
{
				}
				return null;
			case IImage.INVALID_IMAGE :
				return null;
			default :
				return null;
		}
	}
	public String getMimeType( )
	{
		return mimeType;
	}
	public void setMimeType( String mimeType )
	{
		this.mimeType = mimeType;
	}
	public String getImageMap( )
	{
		return imageMap;
	}
	public void setImageMap( String imageMap )
	{
		this.imageMap = imageMap;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.engine.api2.IImage#writeImage(java.io.File)
	 */