> 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-skin-analysis-3-0/lines/forehead-lines.md).

# Forehead Lines

What the Forehead Lines parameter measures, why these horizontal lines form, and how to read the grades it returns.

## About Parameter

Forehead lines are the horizontal wrinkles that appear across the forehead. They form when the frontalis muscle repeatedly raises the eyebrows — for example, during expressions of surprise or concentration. Initially these lines appear only during such expressions, but with age and accumulated muscle activity they can become visible even when the face is relaxed.

## Features

1. Works with 1 and 3 side facial images.
2. Evaluates severity (grade) of forehead lines.
3. Separates and segments deep and fine lines.

## Output

1. Grade from 1 to 6.
2. Vector mask for deep lines.
3. Vector mask for fine lines.
4. Vector mask containing both deep lines and fine lines.
5. Algorithm-assigned skin condition tag (Great, Good, Average, Poor).
6. Amount of lines.
7. Amount of deep lines.
8. Amount of fine lines.
9. Length of lines relative to length of the forehead.
10. Length of deep lines relative to length of the forehead.
11. Length of fine lines relative to length of the forehead.

Note: When a single line has varying severity (containing both deep and fine sections), it is categorized as one deep line rather than a fine line.

## Grades Description

Severity assessment based on the depth and extent of the most prominent wrinkles.

<table><thead><tr><th width="120.4296875">Grade value</th><th width="484.68359375">Description</th><th>Tags</th></tr></thead><tbody><tr><td>1</td><td>Wrinkles are absent, but textural irregularities related to skin dehydration may be present.</td><td>Great</td></tr><tr><td>2</td><td>Fine wrinkles are appearing; they may be barely noticeable or clearly discernible, but there are no deep wrinkles.</td><td>Good</td></tr><tr><td>3</td><td>Fine wrinkles are clearly visible, and deep wrinkles are appearing; however, the deepest part is surrounded by fine wrinkles, and the ridge (or border/edges) of the wrinkle is weakly pronounced.</td><td>Average</td></tr><tr><td>4</td><td>The wrinkles are deepening further, are clearly visible along their entire length, and may extend across the whole forehead but not be deep along the full length; the wrinkle ridge (or border/edge) is pronounced at some places.</td><td>Poor</td></tr><tr><td>5</td><td>A well-defined wrinkle ridge (or border/edge) appears, and the deep wrinkle likely extends across the entire forehead.</td><td>Poor</td></tr><tr><td>6</td><td>The ridge (or border/edge) is excellently pronounced, the deep wrinkle extends across the entire forehead, and the wrinkle may resemble a fold.</td><td>Poor</td></tr></tbody></table>

## Algorithm API

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

See [Forehead Lines Parameter Result Scheme](/haut.ai/developers/saas-api-overview/api-for-face-skin-analysis-3.0/lines/forehead-lines.md).

***

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{% endhint %}

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