> ## Documentation Index
> Fetch the complete documentation index at: https://docs.liminaltattoo.es/llms.txt
> Use this file to discover all available pages before exploring further.

# Compare two photographs with Piel Viva

> Compare checkpoints side by side, align photos manually, and save visual observations with transparent quality limitations.

The **Comparativa** tab in Piel Viva lets you compare two different photographs recorded for the same session.

**1. Select two photographs**

Choose **Foto A** and **Foto B** from the available checkpoints. The images must be different.

**2. Start side by side**

**Lado a lado** displays both images. Use **Zoom conjunto** to inspect them at comparable magnification.

**3. Align manually if needed**

Switch to the overlaid alignment view and adjust the second photo's position, scale, and rotation against recognisable landmarks.

**4. Confirm before using the slider**

The comparison slider requires confirmed alignment. Without alignment, regional differences are not considered reliable comparable evidence.

**5. Save the comparison**

Select **Guardar comparativa y observaciones**. Depending on image quality, the application can report that captures are comparable, limited, or should be repeated.

## Interpreting visual differences

Luminance, contrast, visible detail, and framing can change between photos for reasons unrelated to the skin. A visual difference does not establish a medical or physiological cause.

> [!NOTE]
>
> Automatic image registration is not part of the current beta. Alignment is manual, and comparisons can be labelled as requiring more context.

Use **Notas y criterio del artista** to preserve your interpretation. Return to the [Piel Viva guide](https://docs.liminaltattoo.es/en/piel-viva/guide.md) for photo and region setup.


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