Convert to Image module

The To Image module exports each page of the PDF (or a selection of pages) as a JPEG or PNG image file. It is an export operation: the PDF document currently open is not modified. You reach this module from the Conversion category of the Dashboard.

Pages to convert

Three selection modes are offered, identical to those of the other export modules:

All pages: converts the whole document (default mode);
Selected pages: converts only the pages ticked in the preview grid on the left. The module switches to this mode automatically as soon as a thumbnail is clicked;
Custom range: lets you enter a mixed list of numbers and ranges, for example 1, 3-5, 8.

The Convert button stays disabled as long as the active mode designates no valid page.

Output format

JPEG

A compressed format suited to pages containing many photographic images. For this format, a Quality slider appears:

A scale from 10% to 100%, in steps of 10%;
Default value: 90% — a good compromise between size and visual fidelity;
At 50% or less, compression artefacts may be visible on text. Prefer PNG for pages that are mostly text.

PNG

Lossless compression, ideal for preserving the sharpness of text and vector elements. Files are noticeably larger than in JPEG but no degradation is introduced.

Create a ZIP archive

A Create a ZIP archive switch lets you gather all the generated images into a single .zip file at the end of the export. Very useful for transferring a batch of images by email or messaging while limiting fragmentation. This setting is remembered for subsequent exports.

Resolution

The Resolution section determines how fine the rendering is:

1× (72 DPI): screen resolution. Suited to purely visual use (presentation, quick preview);
2× (144 DPI): default value. A good compromise for most uses, including occasional printing;
3× (216 DPI): higher quality, recommended for quality printing or display on high-density screens;
Custom…: a text field appears for entering a value in DPI. The field only accepts digits. Typical values are 300 DPI (standard printing), 600 DPI (high-quality printing), 1200 DPI (archiving).

The higher the resolution, the more precise the rendering, but the larger the images and the slower the export.

Running the conversion

Click Convert. An "Export operation" dialog reminds you that:

This action will export the generated images directly into the folder of your choice. The current document will stay open and unchanged.

Confirm with I understand to open a macOS destination folder picker. The folder proposed by default is the one configured in Settings > Files.

HtkPDF then writes one image file per selected page, with a name based on the original PDF name and the page number. Invalid characters (accents, punctuation) are automatically cleaned from the prefix to guarantee compatibility with every file system.

While exporting, the button reads "Converting…" and stays disabled. If a ZIP export was requested, an additional step compresses the content through the macOS file coordinator before the final write.

Typical use cases

Previews for the web: exporting each page as a low-resolution JPEG to display as thumbnails;
Preparing illustrations: extracting PDF pages as high-resolution PNGs to integrate into another document, a presentation or a website;
Visual archiving: keeping a visual record of a PDF whose editable layers are not essential;
Distribution without PDF software: turning a document into a series of images to share it with a recipient who has no PDF reader.

Returning to the Dashboard

Once the export has finished successfully, the module closes automatically and the Dashboard is shown again. No change has been made to the PDF.

Note: converting to images rasterises the content — text and vectors are flattened into pixels. It is no longer possible to search or select text in the generated files. To keep a text layer, prefer a conversion to Word or a text extraction with OCR.

Screenshots

1 screenshot — click to enlarge