Mural does not have internal image editing functions. This means you have to use an external image editing program such as Photoshop, GIMP or others.
Resizing images to work in Mural
Mural requires three sizes of images in every item. This is because it is impossible to predict which device will be used to view the story. In addition, we don't know whether the story will be seen in portrait or landscape mode.
It's important to put images in all three sizes; if you only put an image in the Large size, there's a good chance that a user with a lower-resolution device will only see a black screen if the other sizes are left blank.
3 sizes: Small, Medium and Large
Mural's three image sizes are as follows:
Small: 1080 pixels wide X 1920 pixels high. This is a portrait orientation and assumed for mobile phones in a vertical position.
Medium: 768 pixels wide X 1024 pixels high. This is a portrait orientation and assumed for tablet devices in a vertical position.
Large: 1920 pixels wide X 1080 pixels high. This is intended for use on desktop computers.
Mural works with images in JPEG, GIF (including animations) and PNG formats.
In order to save bandwidth, especially on mobile devices, we strongly recommend using a lower image quality setting for JPEG images.
Working with image filenames
We recommend using filenames that correspond to the resized image sizes. This could be something like
imagename-desktop.jpg. Use these consistently, as it will make it easier to work with later on.