docs/user_guide/gaze_analysis_pipeline/background.md


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39

Add a background
================

Background is an optional [ArFrame](../../argaze.md/#argaze.ArFeatures.ArFrame) attribute to display any image behind pipeline visualisation.

![Background](../../img/ar_frame_background.png)

## Load and display ArFrame background

[ArFrame.background](../../argaze.md/#argaze.ArFeatures.ArFrame.background) can be enabled thanks to a dedicated JSON entry.

Here is an extract from the JSON ArFrame configuration file where a background picture is loaded and displayed:

```json
{
    "name": "My FullHD screen",
    "size": [1920, 1080],
    ...
    "background": "./joconde.png",
    ...
    "image_parameters": {
        ...
        "background_weight": 1
    }
}
```

!!! note
    As explained in [visualisation chapter](visualisation.md), the resulting image is accessible thanks to [ArFrame.image](../../argaze.md/#argaze.ArFeatures.ArFrame.image) method.

Now, let's understand the meaning of each JSON entry.

### Background

The path to an image file on disk.

### Background weight

The weight of background overlay in [ArFrame.image](../../argaze.md/#argaze.ArFeatures.ArFrame.image) between 0 and 1.