A word/phrase for something that is the mirror reflection of something else

I'm trying to find a word or phrase for the picture we get when we put everything that is on the right side to the left and every thing that is placed on the left side to the right, while preserving the order in the opposite manner. I mean if we have: pen, pencil, ruler, needle; after reordering we have: needle, ruler, pencil, pen. Or if you have an image, it must be transformed into what you see in the mirror. Or if you have a kettle with its handle on the left side; now after the transformation the handle is on the right side (and actually with reversed image).

By searching the internet I found the words and phrases: Reversed output, mirror output, mirror reflection of the output, reversed output, mirror reversed output. (One more question in parenthesis: Do we have mirrorly reflected output? Are we able to add -ly to mirror to use it as an adverb at all?)

What is the correct and appropriate word for it? I know that if it was just about a string of characters I could use reversed output. But now I have two dimensional objects (like matrices).

As for its part of speech, I want to use the word/phrase as an object, not a verb.

Are you looking for "mirror image" ?

mirror image (noun)

• "something that has its parts reversely arranged in comparison with another similar thing or that is reversed with reference to an intervening axis or plane" MW
• "something that looks exactly the same as another thing but with its left and right sides in opposite positions" Cambridge
• "A mirror image (in a plane mirror) is a reflected duplication of an object that appears almost identical, but is reversed in the direction perpendicular to the mirror surface. As an optical effect it results from reflection off of substances such as a mirror or water. It is also a concept in geometry and can be used as a conceptualization process for 3-D structures." from Wikipedia

Addendum: As for the mirror image of letters, any letter, symmetrical or asymmetrical, has its own mirror image. Symmetrical letters, such as W, M, O, H or T, will produce a mirror image identical to their real image. Asymmetric letters will have their mirror image horizontally inverted, just like a kettle or a teapot. I just can't type here that -------- is the mirror image or "LEFT" because there are no mirror-image keys for L, E and F on the keyboard.

All the terms you collected are not used equally; in fact you find only "mirror output" and "reversed output" (ref.) in any significant number. You can see that "mirror output" has recently come to be the preferred term.

There is also the traditional term "mirror image" and here is how it compares with the other two: ref..
This term has two meanings, a scientific one which can be described by mathemetical transformations"— it has been used in science this way to the present day—, and the meaning of spitting image. It is possibly because of this latter meaning that some new terms appeared.

Apparently, "mirrorly reflected output" is not in use. "-Ly" is a suffix used with nouns so as to produce adjectives but it is not a freely productive suffix.

Anyway, scientifically speaking, if you use this term (mirror image) for the sequential order reversal, in particular for sequences of symbols or groups of symbols, you are likely to use this term as somewhat of a misnommer: the mirror image of "NO" isn not "ON" but "OИ".
Whereas you expect to read normally your reversed sequence normally, a true mirror image will not give you this possibility in many cases. See for instance what the use of this term means in the domain of the development of the program "Word" (mirror image with Word).
I know of no other term you might use with "mirror" in the way of expressing the precise concepts I considered or those you mention. I can't find precise information on the terms you provide and so I don't even know whether they are proper terms for your purpose. However, a standard term from everyday language seems to correspond perfectly to what you need; this is "reverse order" (Merriam-Webster).