visualforce commandlink image and alternative text

<apex:commandLink title="Remove" style="color:red" action="{!removePostRow}" reRender="postPanel" immediate="true" >
                                                                        <apex:image id="theImage" alt="Remove" style="margin-left:20px; margin-top:36px;" value="data:image/png;base64,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" />
                                                                        <apex:param value="{!rowNum}" name="rowToRemove" assignTo="{!rowToRemove}"/>
                                                                    </apex:commandLink>