Extend illustration "canvas" to enable adjustable width/height images

[cbunicef]

As a CONTENT DEVELOPER I want to be able to take existing illustrations and use them in different aspect ratios to meet different requirements on my site. For example, it may make sense for a single illustration to be used in spaces which are horizontal rectangles and also in spaces which are square.

Potential solution: Many of the illustrations that have been produced for IoGT have elements that are centered and don't touch the vertical or horizontal edges of the image:

Using an image editor, it's possible to take these sides where the last line of pixels are all the same color, and extend them to other shapes.

For example this rectangle

becomes this square

by duplicating the top and bottom rows of pixels above and below the image.

The typical dialogue for this in image editing tools is

(example from photopea.com)

Other changes could be done to convert

to

It looks like some of the work needed has already been done by the Image URL Generator UI

[cbunicef]

We can balance the work required to complete this feature against the fact that using a free photo editor isn't THAT difficult.

Pros of adding this feature:

• only one version of each image in the CMS
• less time spent adjusting images
• enables more users to do this work