> For the complete documentation index, see [llms.txt](https://support.aperty.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://support.aperty.ai/how-to-use-aperty/four-key-tools-categories/essential-tools/curves-tool.md).

# Curves Tool

<figure><img src="/files/0cAiy8NAXiu5f3quU4HF" alt=""><figcaption></figcaption></figure>

The **Curves Tool** is a powerful feature in Aperty that allows you to fine-tune the tonal range of your portrait by adjusting brightness, contrast, and color balance. With precise control, you can brighten or darken specific areas, add contrast, or shift the colors to achieve the perfect look for your portrait.

* **Color Selectors**: Use the white (RGB), red, green, and blue selectors to adjust the overall tone or specific color channels. The white selector adjusts all colors, while the red, green, and blue selectors modify individual channels. For example, manipulating blue and yellow tones can cool down or warm up your image by adjusting the blue channel.
* **Control Points**: Add up to 10 control points along the curve to make targeted adjustments to specific tonal areas of the image. Drag a point upward to brighten or reduce shadows in that area, or drag it downward to darken the area and increase contrast.
* **S-Curve**: For an effective contrast boost, create an "S-curve" by placing two control points on the curve. Raise the first point in the highlights section to brighten them, and lower the second point in the shadows to darken those areas. The steeper the curve, the more contrast you'll introduce, giving your portrait depth and pop.
* **Histogram**: The gray graph behind the curve is the histogram, which represents the image's tonal distribution. It helps guide your adjustments by showing how much of the image lies in shadows, midtones, or highlights.
* **Black and White Points**: Adjust the black and white points horizontally to increase contrast or move them vertically to reduce contrast. Horizontal adjustments spread the tonal range for a punchier look, while vertical adjustments flatten it for a softer feel.

{% hint style="info" %}
Use subtle curve adjustments for portraits to maintain a natural look. A gentle S-curve can add depth and contrast without making the image look harsh, and refining individual color channels can help balance skin tones and background colors for a polished final result.
{% endhint %}


---

# 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:

```
GET https://support.aperty.ai/how-to-use-aperty/four-key-tools-categories/essential-tools/curves-tool.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
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.