El negativo perdió color hasta el punto de perder contraste.

Here, negativo is a noun, not an adjective.

• el negativo = the negative, especially a photographic negative
• As an adjective, negativo can also mean negative in other contexts:
  • una respuesta negativa = a negative answer
  • efectos negativos = negative effects

In this sentence, the article el shows clearly that it is being used as a noun: the negative.

Perdió is the preterite of perder, and it presents the loss as a completed change or a definite result in the past.

• perdió color = it lost colour / it faded
• perdía color would suggest an ongoing process: it was losing colour

So the sentence is describing what happened as a whole, not focusing on the process from the inside.

• El negativo perdió color... = the negative ended up losing colour
• El negativo perdía color... = the negative was losing colour

Both are possible in other contexts, but perdió fits a completed description better.

In Spanish, abstract or substance-like nouns often appear without an article after certain verbs, especially when talking about a general quality.

So:

• perder color = to lose colour / to fade
• perder fuerza = to lose strength
• perder importancia = to lose importance

Using perdió el color is also possible, but it sounds more like it lost its colour completely or refers to a more specific colour already understood from context.

Compare:

• La tela perdió color. = The fabric faded.
• La tela perdió el color original. = The fabric lost its original colour.

In your sentence, perdió color is the more natural general expression.

Hasta el punto de means to the point of or to such an extent that.

It introduces the degree or consequence of something.

Structure:

• hasta el punto de + infinitive

Examples:

• Se cansó hasta el punto de desmayarse. = He got so tired that he fainted.
• Llovió hasta el punto de inundar las calles. = It rained so much that it flooded the streets.

So here:

• perdió color hasta el punto de perder contraste
• it lost colour to the point of losing contrast

Because hasta el punto de is a fixed structure, and it is normally followed by an infinitive when the subject stays the same.

So:

• El negativo perdió color hasta el punto de perder contraste.

The same thing — el negativo — both lost colour and lost contrast, so Spanish uses:

• hasta el punto de + infinitive

If the subject changed, Spanish would more naturally use a clause instead, for example:

• ...hasta el punto de que ya no se distinguían los detalles.
• ...to the point that the details could no longer be distinguished.

It can sound a bit repetitive to an English speaker, but it is completely normal in Spanish.

The sentence is saying:

1. It lost colour
2. and that happened to the point of losing contrast

So the repetition of perder is grammatically natural and clear.

Spanish often tolerates repetition more than English does, especially when it keeps the structure simple and precise.

You could rephrase it, for example:

• El negativo perdió color hasta el punto de quedarse sin contraste.

But the original sentence is perfectly good Spanish.

For the same reason as with color: contraste is being treated as a general visual quality, so Spanish often leaves out the article.

• perder contraste = to lose contrast
• ganar contraste = to gain contrast

This is very common with abstract nouns.

If you say perder el contraste, it sounds more specific, as if you are referring to a particular contrast already identified in context.

In most general descriptions of image quality, perder contraste is the most natural option.

Yes. Here contraste is an uncountable / abstract noun, so the singular is normal.

It refers to the overall visual quality of contrast in the negative, not to several separate contrasts.

Just like:

• tener paciencia = to have patience
• perder fuerza = to lose strength
• ganar nitidez = to gain sharpness

So perder contraste means to lose contrast in a general sense.

They are similar, but not always identical in tone.

• perdió color = lost colour / faded
• se decoloró = became discoloured / faded / was bleached

Perder color is often broader and very natural in everyday description. Decolorarse can sound a bit more technical or more specifically like something became bleached or lost pigmentation.

In this sentence, perdió color is simple and idiomatic.

Yes, often it can.

Depending on the context, these are all possible translations:

• to the point of
• to such an extent that
• so much that

For this sentence, natural English translations could be:

• The negative lost colour to the point of losing contrast.
• The negative faded so much that it lost contrast.

The Spanish structure is more literally to the point of + -ing.

Not especially. The sentence follows a very normal Spanish order:

• El negativo = subject
• perdió = verb
• color = object / affected quality
• hasta el punto de perder contraste = result/degree phrase

This straightforward order makes the sentence clear and neutral.

You could change the order for emphasis in other contexts, but the original version is the most natural standard phrasing.