在 wp-includes/js/thickbox/thickbox.js 大概39行的function tb_show(caption, url, imageGroup)中，添加如下行(粗体红色字代表新添加的代码)
复制代码 代码如下:
function tb_show(caption, url, imageGroup) {//function called when the user clicks on a thickbox link

try {
/// 代码省略。。。
TB_NextHTML = "";
TB_imageCount = "";
TB_FoundURL = false;
////// 打开新窗口显示原图
TB_OpenNewHTML = "";

if(imageGroup){
/// 代码省略。。。
if (TB_FoundURL) {
TB_NextCaption = TB_TempArray[TB_Counter].title;
TB_NextURL = TB_TempArray[TB_Counter].href;
TB_NextHTML = "<span id='TB_next'>&nbsp;&nbsp;<a href='#'>"+thickboxL10n.next+"</a></span>";
} else {
TB_PrevCaption = TB_TempArray[TB_Counter].title;
TB_PrevURL = TB_TempArray[TB_Counter].href;
TB_PrevHTML = "<span id='TB_prev'>&nbsp;&nbsp;<a href='#'>"+thickboxL10n.prev+"</a></span>";
}
////// 打开新窗口显示原图
TB_OpenNewHTML = "<span style='font-size: 11pt'>&nbsp;&nbsp;<a href='"+url+"' target='_blank' style='color:red'>查看原图</a></span>";

} else {
　　　　　　　　　　　　　　　　　　　TB_FoundURL = true;
　　TB_imageCount = thickboxL10n.image + ' ' + (TB_Counter + 1) + ' ' + thickboxL10n.of + ' ' + (TB_TempArray.length);
////// 打开新窗口显示原图
TB_OpenNewHTML = "<span style='font-size: 11pt'>&nbsp;&nbsp;<a href='"+url+"' target='_blank' style='color:red'>查看原图</a></span>";
}
}
}
}

/// 代码省略。。。

// Resizing large images - orginal by Christian Montoya edited by me.

/// 代码省略。。。
// End Resizing

TB_WIDTH = imageWidth + 30;
TB_HEIGHT = imageHeight + 60;
//jQuery("#TB_window").append("<a href='' id='TB_ImageOff' title='"+thickboxL10n.close+"'><img id='TB_Image' src='"+url+"' width='"+imageWidth+"' height='"+imageHeight+"' alt='"+caption+"'/></a>" + "<div id='TB_caption'>"+caption+"<div id='TB_secondLine'>" + TB_imageCount + TB_PrevHTML + TB_NextHTML + "</div></div><div id='TB_closeWindow'><a href='#' id='TB_closeWindowButton' title='"+thickboxL10n.close+"'><img src='" + tb_closeImage + "' /></a></div>");
/////// 显示下一张图 + 新窗口查看原图(添加TB_OpenNewHTML)
jQuery("#TB_window").append("<a href='' id='TB_nextImage' title='"+thickboxL10n.next+"'><img id='TB_Image' src='"+url+"' width='"+imageWidth+"' height='"+imageHeight+"' alt='"+caption+"'/></a>" + "<div id='TB_caption'>"+caption+"<div id='TB_secondLine'>" + TB_imageCount + TB_PrevHTML + TB_NextHTML + TB_OpenNewHTML + "</div></div><div id='TB_closeWindow'><a href='#' id='TB_closeWindowButton' title='"+thickboxL10n.close+"'><img src='" + tb_closeImage + "' /></a></div>");


jQuery("#TB_closeWindowButton").click(tb_remove);

if (!(TB_PrevHTML === "")) {
/// 代码省略。。。

效果：
点击“查看原图”后，将在浏览器新窗口(Tab)显示原图。
作者：Elf Sundae (小糊涂)