What's the term for opposite of cropping?

Question

If I extend the canvas of an image with a transparent layer to fill a larger area, then what is that process called in professional graphic design terms?

For instance, see this image courtesy of martin mutch

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I'm writing some free open-source software that will include a function to simply scale an uploaded image to any larger dimension by centering the original image on a transparent background - but I'm not sure what to call this function. The image will never shrink, only grow in size. It will not change the proportion of the image. It will not zoom in. Nothing will be lost (cropped) from the image. Only transparent area would be added. For instance, if you specified you wanted the image 575x575, then it would look like this:

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Notice the added white space above and below the image now to center it on the desired dimensions. What is this process called?

Wordhippo lists some general antonyms for crop, and extend seems good, but I would like to know if there's a professional term for this.

Moreover, I would like to emphasize the transparent layer because I think it should differentiate from anticrop which actually draws more into the picture - which is awesome, but more sophisticated than what I'm talking about which simply adds transparent area.

Answer 1

The closest I think would be Matting, though Enlarge Canvas is probably something more people would know and understand.

Answer 2

This is what some contenders use as terminology

• Photoshop simply calls this Canvas size as such they do not differentiate between sizing up or down. You can also use crop to do the same thing*.
• Gimp calls this Canvas Size. Also they do not differentiate between sizing up or down.
• ImageMagick calls this the image Extent. Also they do not differentiate between sizing up or down.

So it seems that calling it enlarge canvas or canvas padding to loan terminology form the web might be good contenders. On the other hand extend would, to me at least, seem to imply you want to reinvent more data to the image.

* Most image manipulators, including Photoshop, actually can crop and image larger than the original image. So as far as Photoshop is concerned a crop to larger size is just a crop. So the opposite of crop is crop as far as adobe is concerned.