> For the complete documentation index, see [llms.txt](https://docs.saas.haut.ai/haut.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.saas.haut.ai/haut.ai/haut.ai-features/algorithms/face-metrics-2-0/lines-algorithm.md).

# Lines Algorithm

What the Lines Algorithm measures, the facial areas it covers, and how to read the Lines Score it returns in Face Metrics 2.0.

## About Algorithm

1. This Algorithm estimates the visible presence and severity of lines (wrinkles) caused by the loss of natural moisture and elasticity of the skin, including the multiple fine and deep wrinkles, downward shifts of nasolabial folds, marionette folds, and jowls.
2. This Algorithm estimates indicated skin health parameters on: forehead, right eye area, left eye area, right cheek, left cheek.
3. The Main Metric for this Algorithm is the Lines Score, with a range from 0 to 100.
   1. Values from 80 to 100 are considered as a relatively good skin condition.
   2. Values from 50 to 80 are considered as visible lines presence. It is worth noticing that for some age groups, this presence might be normal due to the ageing process.
   3. Values below 50 are considered as an alerting skin condition, that might require specialist attention.
   4. Lines Score is a non-linear combination of the Submetrics.
4. There are several Submetrics for this Algorithm:
   * Sagging score evaluates the severity of face sagging. The higher the value of this parameter, the more pronounced the sagging of the skin is.
   * Jowls class value the grade of jowls severity in the range \[1, 4]. The higher the grade, the more pronounced the jowls are.

***

## Algorithm API

{% hint style="warning" %}
API access is available only for <mark style="color:purple;">**Professional**</mark> plan clients
{% endhint %}

See [Lines Result Scheme](/haut.ai/developers/saas-api-overview/api-for-face-metrics-2.0/wrinkles.md).

***

{% hint style="warning" %}
Not a Haut.AI client yet?
{% endhint %}

<a href="https://haut.ai/book-a-demo?utm_source=referral&#x26;utm_medium=saas_docs&#x26;utm_campaign=Docs_SaaS_HautAI" class="button primary" data-icon="user-vneck">Book a demo</a> <a href="https://haut.ai/product/ai-skin-analysis?utm_source=referral&#x26;utm_medium=saas_docs&#x26;utm_campaign=Docs_SaaS_HautAI" class="button secondary" data-icon="external-link">Platform overview on haut.ai</a>


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://docs.saas.haut.ai/haut.ai/haut.ai-features/algorithms/face-metrics-2-0/lines-algorithm.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.