#  `mutate_content`

Mutate page content streams using a user-supplied Python script
## Usage
> pdftl `<input>` `mutate_content` `<script.py[::func]>` `[<script_args>...]` `output` `<output>`

## Details
The `mutate_content` operation allows you to run custom Python
logic against the raw instruction streams of a PDF. You can specify
your own Python script, and the function from that script to run. The
default function search for if no function is specified is `mutate`.

### The Context Dictionary
Your function receives a `context` dictionary with the following keys:

- `pdf`: The current `pikepdf.Pdf` object.
- `page_num`: The current page number (1-indexed) or `None` for XObjects.
- `is_xobject`: Boolean, `True` if mutating a Form XObject.
- `object`: the `pikepdf.Object` (either a page or an XObject) containing the content stream.
- `args`: A list of extra arguments passed via CLI after the script name.


### Passing Arguments
You can pass custom parameters to your script:
`pdftl in.pdf mutate_content script.py 1.5 2.0 output out.pdf`
In this case, `context['args']` would be `['1.5', '2.0']`.
## Examples

> Mutate content streams in all pages using the `mutate` function in `mutate_grayscale.py`
```
pdftl in.pdf mutate_content mutate_grayscale.py output out.pdf
```

> Fix hairlines using `mutate_hairline_fixer.py`, passing the script the argument '0.5'
```
pdftl in.pdf mutate_content mutate_hairline_fixer.py 0.5 output out.pdf
```


**Tags**: content_stream, custom, advanced

*Source: pdftl.operations.mutate_content*

*Read online: [https://pdftl.readthedocs.io/en/stable/operations/mutate_content.html](https://pdftl.readthedocs.io/en/stable/operations/mutate_content.html)*

*Type: Operation*