Perspec

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  <span style="position: relative; bottom: 0.7rem;">
    Perspec
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App and workflow to perspectively correct images.
For example whiteboards, document scans, or facades.

![Screenshot of Perspec app](images/screenshots/2026-04-23t1013_detected_corners.png)

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- [App Workflow](#app-workflow)
  * [1. Take photos](#1-take-photos)
  * [2. Open Perspec app](#2-open-perspec-app)
  * [3. Select photos to correct](#3-select-photos-to-correct)
  * [4. Save the corrected image](#4-save-the-corrected-image)
  * [Combine several photos into PDFs](#combine-several-photos-into-pdfs)
- [Installation](#installation)
  * [Prebuilt](#prebuilt)
  * [From Source](#from-source)
- [Usage via CLI](#usage-via-cli)
- [Interface Scaling](#interface-scaling)
- [Photo Digitization Workflow](#photo-digitization-workflow)
  * [Additional Steps](#additional-steps)
- [Technologies](#technologies)
- [Related](#related)
- [License](#license)

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## App Workflow

### 1. Take photos

Perspec is great for correcting photos of documents, receipts,
whiteboards, facades, or any other planar objects.

<img src="images/examples/package_slip.png" alt="Photo of a document on a table" style="max-width: 30rem;" />


### 2. Open Perspec app

<img src="images/screenshots/2026-04-23t1006_select_files.png" alt="Opened Perspec App" style="max-width: 35rem;" />


### 3. Select photos to correct

Either use the "Select Files" button or simply drag & drop the photos onto the window.

Perspec's integrated computer vision algorithms will automatically detect
the corners of the document and mark them with circles.

```text
    Red o----------------o Green
        |                |
        |    Document    |
        |                |
Magenta o----------------o Blue
```

If the corners are not detected correctly,
you can manually drag the circles or the edges to the correct position.

To place corners outside of the photo
or to position them more precisely,
zoom with the − and + buttons in the bottom right corner
(or the − and + keys).
Click the zoom level (or hit 0) to show the whole photo again.
Drag the photo with the right or middle mouse button
or move it with the arrow keys.

<img src="images/screenshots/2026-04-23t1756_detected_corners.png" alt="Dropped image" style="max-width: 40rem;" />


### 4. Save the corrected image

Either click one of the save buttons or hit Enter to save the corrected image.

This will save the image in the same directory
as the original photo with `-fixed` appended to the filename.

If you selected multiple photos, they will be opened one after another,
sorted naturally by their path (e.g. `IMG_9.jpeg` before `IMG_10.jpeg`).

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