How to Use the Post Image or Thumbnail Image Field in Thesis


Many of the sites we build for our clients are built using the awesome Thesis theme, and incorporate the use of the Thesis-specific functionality of post images and post thumbnail images.  Using post images or thumbnail images associate a particular image with that post so that it can be dynamically included in excerpts or teasers.

Wide Hive - Small Images
This post thumbnail image is essential to this archive of Wide Hive Records’ discography.
Wide Hive - Full Size Images
The same image is rendered at a different size on the full post page.

When you specify a post image that image is automatically resized as a thumbnail image for the pages that use teasers. Some websites don’t use teasers, but that’s no reason not use the thumbnail image functionality.

Specifying a post image or thumbnail image

First you want to find a post image to use.  You want to use a post image that is sized correctly according to your website.  Sizes are specified in the User Manuals that we create for our clients. Resizing images is easy to do using Google’s free software, Picasa.

Once you have your post image sized correctly and while you are editing the post in question, upload it using the image uploader.

Upload Image Button
Use the first button next to Upload/Insert to upload an image.

Select the file you have sized correctly for the post image from your harddrive, and it will upload.

The Link URL field after image is uploaded.
Copy the web address in the Link URL field.

Close the light box and scroll down until you see the Post Image URL field.  Paste the web address there and add alt text, a bit of text to describe the image, below.

Thesis automatically resizes the post image to be the correct size for a thumbnail.  Isn’t that nice?

Sometimes you may want to have a thumbnail image but not a post image.  In that case, follow the instructions above but paste the web address in the Thumbnail Image URL  instead of the Post Image URL field.  Fill the Thumbnail Image Alt Text with the relevant alt text.

Thumbnail Images for Posts Using the WordPress Image Gallery

Because of the way the WordPress Image Gallery works, any image that you upload using the image uploader when editing the post is included in the Image Gallery.  This can cause the Image Gallery to include the image multiple times or include a poorly sized version.

In these situations, use the Add New link under Media to upload your image.

Select the correctly sized image on your hard drive as above, and it will upload.

Select Image
Copy the File URL.

Go back to the post you were editing, and paste this URL into the Post Image URL field or the Thumbnail Image URL field, whichever is appropriate for your situation.  Now your Post Image or Thumbnail Image won’t display in your WordPress Image Gallery!

About the Author:

Leader of the Artsy Geek team and creator of Camp Artsy Geek, Jen comes from a long line of get-rich-quick-schemers. A serial entrepreneur, she launched her first business at the age of 12: a crocheted goods pop-up. A lover of good design and effective marketing, Jen believes that life -- and business -- should be fun and enjoyable. Life is short! Follow your dreams and train your brain to support your success. We're in this together. Rock on!


  1. I use the Post Image capability to display the lead image and thumbnail as appropriate as you’ve described.

    One problem with this approach, however, is that there does not seem to be a way of displaying a caption under the image if you do it this way. And by “caption” I don’t mean “alt” text, which should be a verbal description: I mean a label for the image. There really ought to be a “caption” field in the “Post Image” section that lets you do this.

    There are a few plugins that claim to be able to pull “title” or “alt” text to display as a picture caption, but a) they all seem to be very old, often unsupported and not tested with current WP; and b) they seem to offer “all or nothing” – ie ALL your images get captions – or don’t.

    Most of the time I only need a caption on an image occasionally, and I really need to be able to display a caption only a specific image. Any ideas on how to do this? Any suggestions welcome.

    BTW, I wonder if Thesis really should be using Featured Image for the lead image in a post – maybe that’ll be added in a later version…

    32 Reply
    1. Hey Richard,

      I agree that the lack of caption functionality is an issue. I’ve noticed that some people put a bit of a caption either at the beginning or the end of the post. The end of the post is appropriate when linking to the photographer or the source of the image; you can say something like “Post image courtesy of Ann Smith.”

      Unfortunately this isn’t helpful if you want to use the post image as an instructive part of your post. Normally in those situations I use an unimportant photo for the post image and include the instructive image as part of the main body content with a caption.

      I’m hoping that Thesis introduces featured images as post image in the future. However, I’m not sure how that would work when you want to specify a separate thumbnail image. I did find a plugin over at that turns the featured image into the post image. It’s great to have so many developers working on Thesis!

      36 Reply

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