[css-backgrounds]/[css-images]: Proposal add image-center definition for auto sizing images

[SetTrend]

Very often I find myself using asymmetric images.

When I use the cover sizing rule on those images, it regularly happens that important parts get cropped or unimportant parts, like bosoms, are the only thing left after rotating a device.

So, I'd like to propose to create a new CSS rule, allowing to provide the center point around which the image is centered when cover is used.

The proposed new rule may accept the same values as the background-position rule.

I suggest the following names for the proposed attribute: background-image-center and object-center.

Here's an animation, depicting the suggested rule and behaviour:

The red cross depicts the position declared by the proposed rule.

[tabatkins]

That's not a bad idea. The "Twitter image-crop fails" problem is very real. The properties seem reasonable to me too. I don't think we'd really need to extend this to other image-taking properties.