If you’re posting an image on Mastodon and there is a particular part of the image that you want people to pay attention to, it is recommended that you set the image’s “focus” on this part. This setting tells Mastodon which part of the photo is most important, and it means Mastodon will prioritise showing that part of the image if it ever has to display a cropped preview version.
Here are some possible situations where people may see a cropped preview of your image on Mastodon:
- If you attach multiple images in the same post
- If people are viewing timelines on older versions of Mastodon or Mastodon forks based on older versions
- If people are viewing timelines on certain apps
Whatever the reason, people can still see the full non-cropped version if they click on the post or the image itself, it’s only the preview versions of images that may be cropped in certain circumstances.
How do I adjust an image’s focus so that previews always show a certain part of the image?
- Log onto your server’s website, the web app or your app
- Start creating your post and attach the image, but don’t publish it yet
- If you’re using the website or web app, click Edit on the image (other apps will have their own ways of adjusting images)
- Move the circle to the part of the image you want people to see the most
- Remember to add a text description to the image
- Click Apply
- When you’ve finished writing your post, click Publish
(Some of these steps may be called different things or be done in a different order on different apps. Hopefully these instructions give you the general idea.)
Wait, images are cropped on Mastodon?
Images aren’t cropped, but the preview versions of them may be cropped in certain circumstances. Even if people see a cropped preview, the original version is visible if people click on a post or the image itself.
On some versions of Mastodon’s web interface, and on some apps, timelines show all previews in a 16:9 aspect ratio. This means any images not in 16:9 are shown in cropped previews. People can click on the post or image to see the full original version, but while it’s on their timeline alongside other posts it may be shown cropped.
What if I don’t adjust the focus?
If you don’t adjust the focus, it will default to focusing on the exact centre of the image. This can cause portraits of people to be shown without their heads, for example.
I can’t see any photos cropped to 16:9 on my timeline?
The latest version of Mastodon’s web interface doesn’t crop previews of individual images any more, but people on other versions of Mastodon, other types of Fediverse server or other apps may see things differently. Also, attaching multiple images can cause cropping of previews on whatever you are using.
If you want a photo preview to look nice, it’s always worth adjusting its focus setting.
What if the image is already 16:9 aspect ratio?
Images that have a 16:9 aspect ratio will not seem to show any differences when you adjust the focus setting, but it’s still worth adjusting the focus as some previews may be a different aspect ratio (for example if you’re attaching multiple images in a single post).
What if there are multiple images attached? What happens then?
It depends on how many attachments you have, and what kind of software is being used by the person who sees your post. The aspect ratio of previews will usually change as you add more images and it tries to tile them together in your post.
Can I adjust the focus setting after posting an image?
Yes, you can use Mastodon’s edit feature to adjust the focus after the image has been posted.
What does “aspect ratio” mean? Why 16:9?
Aspect ratio is how wide something is compared to how tall it is. For example, if an image is 1000 pixels wide by 1000 pixels tall, it would have an aspect ratio of 1:1. If it was 2000 pixels wide by 1000 pixels tall, it would have an aspect ratio of 2:1.
The 16:9 aspect ratio is very common on cinema screens, TV sets, laptops, smartphones, games consoles etc. The popular 1080p standard has pictures displayed at 1920 pixels wide and 1080 pixels tall, which means it has an aspect ratio of 16:9.
I thought Mastodon had got rid of cropped previews on the latest version?
Individual images are no longer cropped to 16:9 on the latest version of Mastodon’s website, but not everyone is on the latest version, not everyone uses the website or the same apps, and not everyone is on Mastodon.
Also, if you’re attaching more than one image to the same post, then they will be shown as cropped previews whatever version you or other people are using.