Bakgrunden på den här bilden är mörk, men hennes ansikte är fortfarande skarpt.

Because bakgrunden is the definite form of bakgrund.

• en bakgrund = a background
• bakgrunden = the background

In this sentence, it means the background of this particular picture, so Swedish uses the definite form.

Also, Swedish often uses the definite form when the noun is made specific by a phrase like på den här bilden.

Because in standard Swedish, when you use den här with a noun, the noun usually also takes the definite ending. This is called double definiteness.

So:

• den här bilden = this picture
• not normally den här bild

This is different from English, where this picture does not change the noun.

A useful pattern is:

• den här + en-word in definite form
• det här + ett-word in definite form
• de här + plural definite form

Examples:

• den här bilen = this car
• det här huset = this house
• de här böckerna = these books

This is a very common difference between English and Swedish.

Swedish often uses på with pictures, photos, screens, and images:

• på bilden = in/on the picture
• på fotot = in/on the photo

So even though English often says in this picture, Swedish normally says på den här bilden.

Think of it as an idiomatic Swedish choice rather than a word-for-word match.

Because after a possessive word like min, din, hans, hennes, vår, deras, Swedish normally uses the indefinite form of the noun.

So:

• hennes ansikte = her face
• not hennes ansiktet

Compare:

• ansiktet = the face
• hennes ansikte = her face

This is very different from English, because English does not show this contrast on the noun itself.

More examples:

• min bok = my book
• hans bil = his car
• deras hus = their house

Because Swedish adjectives agree with the noun.

Here, the two nouns have different grammatical genders:

• bakgrund is an en-word
• ansikte is an ett-word

When an adjective is used after är (a predicative adjective), it still agrees with the noun:

• Bakgrunden är mörk
• Ansiktet är skarpt

So:

• mörk = used with a singular en-word
• skarpt = used with a singular ett-word

Compare:

• en bil är snabb = a car is fast
• ett tåg är snabbt = a train is fast

Unfortunately, not usually a reliable rule. You normally have to learn the gender with the noun.

So it is:

• ett ansikte = a face

That is why the adjective becomes:

• ett ansikte är skarpt

Many learners memorize nouns together with their article:

• en bakgrund
• en bild
• ett ansikte

That makes agreement much easier later.

Fortfarande means still.

In this sentence:

• hennes ansikte är fortfarande skarpt
  = her face is still sharp

Its position is normal in Swedish main clauses: it often comes after the finite verb.

So:

• är fortfarande skarpt
  not usually
• fortfarande är skarpt

This is connected to Swedish word order, where the finite verb usually comes early in the clause.

Because Swedish main clauses follow the V2 rule: the finite verb usually comes in the second position.

In the second clause:

• hennes ansikte = first element
• är = second element

Then the adverb fortfarande comes after the verb.

So the normal order is:

• hennes ansikte är fortfarande skarpt

If you move something else to the front, the verb still stays second:

• Fortfarande är hennes ansikte skarpt

That is a very important Swedish pattern.

Yes. Both are possible, but they feel a little different.

• den här bilden is very common in everyday speech
• denna bild is more formal or written

So:

• Bakgrunden på den här bilden ... sounds natural and conversational
• Bakgrunden på denna bild ... sounds more formal

In standard Swedish, you normally choose one pattern or the other:

• den här bilden
• denna bild

but not usually:

• denna bilden

Yes, but in photo/image contexts it means sharp, clear, or in focus.

So hennes ansikte är fortfarande skarpt means her face is still clearly focused, even though the background is dark.

This is a very natural use of skarp in Swedish, especially for:

• images
• photos
• text
• outlines
• details

For example:

• Bilden är skarp = The image is sharp
• Texten är skarp = The text is sharp/clear

Because men joins two full clauses:

• Bakgrunden på den här bilden är mörk
• hennes ansikte är fortfarande skarpt

In Swedish, a comma before men is very common and standard when it connects two independent clauses.

So the comma helps show the contrast:

• the background is dark, but
• her face is still sharp

It works much like English punctuation here.