I recently worked on a site that had hundreds of blog posts with images that were square. After updating to Divi and creating a homepage with a blog grid layout, all of these images were cropped to Divi’s 400 x 284 rectangular thumbnail size. In this particular case, the images had text at the top and bottom that were cut off from the new image size. Luckily I found a fairly simple solution for changing the image size that the blog module loads. I also found a WordPress function that will add a thumbnail size with the correct aspect ratio when new images are uploaded. If the images you want to change are already uploaded to your site, you’ll need to regenerate the thumbnails AFTER applying this tweak using this plugin. The following solution works for both the blog module and the portfolio module.

PHP

The first thing you’ll want to do is create a file in your child theme folder and name it functions.php. If you already have a child theme installed properly, this file should already exist. Here is a tutorial on creating a child theme.

Your file location should be this /wp-content/themes/Divi-child/functions.php

Now just copy and paste the following code into this file to change the blog module image sizes:

In the code snippet above, the first section is simply importing your child theme style.css file. You should already have this or something similar in your functions.php file. The next section of the snippet changes the blog module image size and adds a this thumbnail size when new images are uploaded.

You’ll want to change the 400 value to whatever image size you need. The following line from above is what adds a new thumbnail size:

You can find more information about this function in the WordPress docs. The function above resizes the uploaded image proportionally, without distorting. You can also hard crop the image by adding a true parameter to the function:

This would hard crop the image from the center position vertically and horizontally. You can change the crop position by adding position values to the function, starting with the horizontal position followed by the vertical:

And finally, if you want to change the portfolio module, you would use this snippet instead:

Keep in mind if you want to change the image sizes for both the blog and portfolio module, you only need to include the add_image_size function once. That is if the images sizes will be the same for both modules. If they will be different, you can include the function twice with different values for each image size. Just make sure the thumbnail name is different for each function: