La resolución afecta al contraste.

Because the verb is commonly used as afectar a when it means to affect something or someone.

So the structure is:

• afectar a + noun

Here, a + el contracts to al:

• a + el contraste = al contraste

So:

• La resolución afecta al contraste.

This a is part of the verb pattern, not a translation of English to.

Afecta is the:

• 3rd person singular
• present indicative
• of the verb afectar

It matches the subject la resolución, which is singular.

So the pattern is:

• la resolución afecta
• the resolution affects

Other present-tense forms would be:

• yo afecto — I affect
• tú afectas — you affect
• él/ella afecta — he/she/it affects
• nosotros afectamos — we affect
• vosotros afectáis — you all affect
• ellos/ellas afectan — they affect

Spanish uses articles much more often than English does.

In this sentence, la resolución can mean:

• the resolution in a specific context, or
• a general/known concept depending on context

English sometimes drops the article where Spanish keeps it, but Spanish usually prefers an article with nouns like this.

Also, resolución is a feminine noun, so it takes:

• la resolución

not

• el resolución

Again, Spanish often uses the definite article where English does not.

So even if English says:

• Resolution affects contrast

Spanish often says:

• La resolución afecta al contraste

The article can sound natural in Spanish when referring to:

• a general concept
• a specific feature already understood from context

So el contraste is perfectly normal here.

Yes, resolución is feminine:

• la resolución

A very useful pattern is that many nouns ending in -ción are feminine:

• la resolución
• la situación
• la información
• la decisión

So -ción is a strong clue that the noun is feminine.

The accent mark in resolución shows where the stress goes:

• re-so-lu-ción

The stress falls on the last syllable.

Without the accent mark, Spanish pronunciation rules would suggest a different stress pattern, so the written accent is necessary.

Approximate pronunciation in Spain:

• reh-so-loo-THYON in much of Spain
• reh-so-loo-SYON in Latin America and some parts of Spain

The final -ción is very common in Spanish and is always stressed there.

Not exactly.

The personal a is the a used before specific human direct objects, as in:

• Veo a María. — I see María.

In afecta al contraste, contraste is not a person, so this is not the personal a.

Instead, this a belongs to the verb pattern afectar a.

So the safest way to think about it is:

• learn afectar in this meaning as afectar a algo/alguien

In standard Spanish for this meaning, afecta al contraste is the safer and more natural choice.

That is because afectar is very commonly used with a:

• afectar a algo
• afectar a alguien

So for learners, it is best to use:

• La resolución afecta al contraste.

You may sometimes encounter variation in some contexts or regions, but afectar a is the form you should learn and use.

The basic word order is:

• Subject + verb + complement

So here:

• La resolución = subject
• afecta = verb
• al contraste = complement

This is a very normal Spanish sentence order and matches the English pattern quite closely:

• The resolution affects the contrast.

Spanish can change word order for emphasis, but this version is the neutral, standard one.

You could make either noun plural, depending on the meaning.

For example:

• Las resoluciones afectan al contraste.
  The resolutions affect the contrast.

• La resolución afecta a los contrastes.
  The resolution affects the contrasts.

• Las resoluciones afectan a los contrastes.
  The resolutions affect the contrasts.

Notice the changes:

• la → las
• afecta → afectan
• al → a los when the noun becomes plural

Because al only exists as the contraction of:

• a + el

There is no contraction with los, so you say:

• a los contrastes