> For the complete documentation index, see [llms.txt](https://docs.viesus.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.viesus.com/features/native-pdf-enhancement.md).

# Native PDF Enhancement

VIESUS enhances PDFs without flattening them. It opens the source PDF, locates the raster images embedded inside, enhances each one through the standard VIESUS pipeline, and writes the improved images back into a new PDF — preserving the document structure, fonts, layout, and vector elements.

This means a photobook PDF, a marketing catalogue, or a print-ready document can be enhanced once at the production stage without anyone redoing the layout.

## Example

{% columns %}
{% column %}
**Before**

<figure><img src="https://919968377-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FG3eQlcnlDKtn9yl3mxsx%2Fuploads%2Fgit-blob-2aac38d3a6989f640b75c2aeecf11934ec13a3c3%2Fplaceholder.svg?alt=media" alt="Before — Native PDF Enhancement"><figcaption></figcaption></figure>
{% endcolumn %}

{% column %}
**After**

<figure><img src="https://919968377-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FG3eQlcnlDKtn9yl3mxsx%2Fuploads%2Fgit-blob-2aac38d3a6989f640b75c2aeecf11934ec13a3c3%2Fplaceholder.svg?alt=media" alt="After — Native PDF Enhancement"><figcaption></figcaption></figure>
{% endcolumn %}
{% endcolumns %}

## What makes it "native"

* **No flattening.** The PDF stays a PDF. Text remains text, vectors remain vectors, layers and metadata are preserved.
* **Image-by-image enhancement.** Each embedded raster image is extracted, run through VIESUS, and written back. Non-image content is untouched.
* **Tiled-image reconstruction.** Layout applications often split a single visual into many small image tiles. VIESUS recognises these split tiles, reassembles them into the single image they represent, and enhances the whole — avoiding visible seams where tile boundaries used to be.
* **Background-image skipping.** Page-sized background images (decorative or full-page color backgrounds) can be detected and skipped so that only meaningful content images receive enhancement.

## How to use it

Native PDF enhancement is delivered by the **VIESUS PDF Enhancer** — a separate command-line tool with stand-alone and hotfolder modes. The image enhancement parameters configured through `viesusini.json` apply to each embedded image; PDF-specific pipeline settings live in the PDF Enhancer's own `settings.json`.

See the [PDF CLI reference](/reference/pdf-cli.md), [Installation](/installation/pdf.md), and [PDF Settings Reference](/configuration/pdf-settings.md).


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