Before we tackle WordPress images, there are four things you need to understand:
- WordPress can’t run without a theme that controls its appearance.
- There are different types of WordPress pages, those with “content” that are created by humans, commonly known as “pages” and “posts,” and those that are automatically generated by WordPress, including “category” and “blog” pages.
- In general, authors can control the sizes of images on content pages and cannot control their sizes on automatically generated pages.
- Human-created pages and posts may contain multiple images within the content (as is the case with this post, for example). Additionally, the author may designate any image as the “featured” image. It is important to note that the featured image does not have to be one of the images in the content of the page or post. The WordPress default is no featured image, so if the author takes no action there will be no featured image. Designating an image as “featured” has various ramifications depending on the theme being used.
When an image file is uploaded to the WordPress media library, WordPress saves the original file (as “full size”) and automatically generates three copies of it in different sizes. The names and default dimensions, in pixels, of those copies are:
- Thumbnail (80×80)
- Medium (300×300)
- Large (1024×1024)
Note that if the original image is smaller than 1024 (or 300), the software will not generate copies in the “large” (and “medium”) sizes.
When an author chooses to add an image to a page or post, the author may specify one of the four sizes (thumbnail, medium, large or full).
Themes often direct WordPress to save each image in additional sizes so that they are available for various uses by the theme. Some themes save each image in more than 10 sizes!
Editing WordPress images
To edit WordPress images, you may either go to the media library, hover over the image to be edited and then click “edit,” or, while in the post/page visual editor, click on the image to be edited and then click on the pencil icon in the top left (see screen shot).
Images can be edited in multiple ways and then the changes can be applied to the thumbnail only, all image sizes (including the thumbnail) or all sizes except the thumbnail.
Automatically generated pages
In general, pages automatically generated by WordPress include the featured images of the applicable pages and posts in specific sizes as dictated by the theme. However, we have encountered themes that don’t make use of featured images.
When the “full size” of a featured image is smaller than the size that the theme specifies for a specific use, blank space is automatically added next to the image to fill the void. To avoid the void, pick featured images that are at least as large as the real estate where the theme displays them.
Very soon after people begin to understand how WordPress images work, they typically ask “Can I change the image sizes?”
Yes, you can. To change the WordPress media settings, go to the “Settings” tab and choose “Media.” See the screen shot below.
Exact vs proportional thumbnails
There is a WordPress setting that allows you to choose between “exact” and “proportional” thumbnails. Exact thumbnails will have set widths and heights, and WordPress will crop images, as necessary, regardless of their original proportions, to conform to the specified exact proportions.
If thumbnails are left “proportional,” they will maintain their original aspect ratios (height to width).
Which is better? It depends. If multiple thumbnails appear on one page, as they would on a blog page, keeping them an exact (uniform) size is usually more pleasing to the eye. However, the automatic cropping that WordPress performs may not yield an optimal appearance.
Allowing thumbnails to remain proportional tends to result in images that display better, but depending on their aspect ratio, they may detract from the overall appearance of pages and posts.
Can the image sizes controlled by the theme be changed?
Yes, but. Yes, the theme’s defined sizes can be changed, but we typically don’t advise it because in our experience when you change the pre-set sizes it tends to screw up various layouts/designs controlled by the theme. Altering the image sizes specified by a theme always requires creation of a child theme – a task that is probably best left to a knowledgeable developer. For most folks, it would be cheaper and easier to pick a new theme with image sizes they like than to modify a theme.
As always, /buzzquake is here to help. Feel free to call us if you get stuck, need more information or would like us to make changes for you.