The most usual way of saying is to use the phrase "2D image". Although the second version is correct too. For example - when I have enough free time, I try to creat a proper 2D image on my laptop
最も普通の言い方は "2D image" です。ただ、二つ目の言い方も正しいです。
例：
When I have enough free time, I try to create a proper 2D image on my laptop
（暇な時は、ラップトップで2次元画像をつくっています）
You'd like to know what you call a 2D image. Well, in general it is not necessary to call a 2D image '2D'. The context of the conversation will define what kind of image it is. For example, if you are looking at photographs, you would not say:'Look at this 2D image'. Or if you are looking at a film, you would not say 'Look at these 3d images'. However, if you are distinguishing between different types of image, you may say something like: 'I prefer a 3d image to a 2d image' for example.
「二次元画像」の言い方を知りたいということですね。
一般的には、二次元画像を '2D' と言う必要はありません。文脈で伝わるからです。例えば、写真を見ていて、'Look at this 2D image'（この二次元画像を見て）のように言うことはありません。
あるいは、映画を見ていて 'Look at these 3d images'（この3D映像を見て）のように言うこともありません。
ただし、画像の種類を区別するときには、例えば次のように言えます。
'I prefer a 3d image to a 2d image'
（私は2D画像よりも3D画像の方が好きです）
If you would like to what what to call a flat image or 2 dimensional image, you can use the term “2-D” for short which stands for “2 dimensional”. This is the standard way people normally refer to a 2-D image.
"A 2 dimensional Image" is one with no depth but it has length, commonly used in Cartoons.
" A 2D image" is a shortened version of the above phrase, and is more commonly expressed in everyday English.
"A 2 dimensional Image" は「長さや幅はあるが奥行きのない画像」のことで、漫画でよく使われます。
"A 2D image" は上のフレーズの短縮形です、日常会話で使われます。
An object is describes as 2-dimensional if it has length and width but no depth.
The adjective two-dimensional can be used to describe works of art for example works of art that are on a flat surface.
People can also be described as being two-dimensional. Such is person is simple and does not think about things deeply enough.
Example: I'm really disappointed with my brother for being so two-dimensional. He bought a house without an inspection or any checks on the property.
"two-dimensional" は、長さと幅はあるものの奥行きがないものを表します。
形容詞の "two-dimensional" は、平面の芸術作品を表します。
"two-dimensional" は、人についても使われます、「単純で物事を深く考えない」という意味があります。
例：
I'm really disappointed with my brother for being so two-dimensional. He bought a house without an inspection or any checks on the property.（弟の単純さには失望した。彼は物件を確認せずに家を買った）
This means that the image/form/representation has
two dimensions. Two dimensions refers to a picture
or illustration that is flat, i.e. it has height and width
but no depth.
Referring to a person as being two dimensional is not
very complimentary because it means that the individual
is very uninteresting/boring and has no unique outstanding
character traits.
"Two-dimensional" は "Having two dimensions"（二つの次元を持つ＝長さと幅はあるが奥行きがない）という意味です。
人について "Two-dimensional" を使うと、これは「おもしろみがない人／つまらない人」というネガティブな意味になります。
"A two-dimensional image."
This is the full expression which refers to an image which has length but no depth and doesn't look real.
"A 2D image."
This phrase is the shortened version of the first phrase and is more common in spoken English.
"A two-dimensional image."（二次元画像）
これは「二次元画像（長さ・幅はあるが奥行きのない、あまりリアルでない画像）」のフルの言い方です。
"A 2D image."（二次元画像）
これは一つ目のフレーズの短縮形です。話し言葉ではこちらの方がよく使われます。
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