How do I edit a custom image mask shape?

I'm trying to edit an existing shape, but it seems that once a shape is used to mask a photo, it is no longer editable. An in fact, once you mask a photo with a shape, you can't even remove the photo and get back to the original shape.

Once an image is masked with a shape, the shape is replaced with a masked image.

Images can't use "Make Editable".

Therefore, if you need to edit a shape after the image is added on to a shape, use this workaround:

• create a custom shape in a new blank presentation, save the Keynote file to be used only to store these custom shapes
• each time you want to edit or add a new shape to your presentation, edit the shape in the customs shape Keynote file
• copy it on to the slide that will be used for the presentation
• add an image to the custom shape

From my original post:

If I go to Format>Shapes and Lines, "Make Editable" is grayed out.

Your video shows it is an image on the slide, it is not a shape.

Shapes in Keynote are vectors, they are lines and curves based on a mathematical formula and they can be edited using

Format > Shapes and Lines > Make Editable

Image files placed in Keynote are bitmap images made up from pixels and can't use Format > Shapes and Lines > Make editable

I want to edit the shape after the photo has been masked with it.

It is not possible to do that, as it is an image that is on the slide having been masked with a shape,

Only shapes can use Make Editable.

Therefore you will need to use the procedure I suggested in my previous post:

• Place a shape on the slide using: Insert > Shape and select one of the shape types.
• Size and position the shape.
• You can edit the form of the shape by selecting the shape then go to: Format > Shapes and Lines > Make editable
• Drag an image onto the shape on the slide, it will open in the mask tool, you can now size and position the image as required to fit in the shape.

Place a shape on the slide using: Insert > Shape and select one of the shape types.

Size and position the shape.

You can edit the form of the shape by selecting the shape then go to: Format > Shapes and Lines > Make editable

Drag an image onto the slide, it will open in the mask tool, you can now size and position the image as required to fit in the shape.