PNG files usually come from screenshots, exported charts, diagrams and logos rather than from cameras, and they are frequently the awkward format to hand over — an email attachment of fourteen separate PNGs is far less useful than one PDF. This tool binds them into a single document, one image per page, with the original PNG data embedded losslessly by pdf-lib.
Because the PNG bytes are copied in rather than decoded and recompressed, screenshots stay pixel-perfect: no JPEG ringing around UI text, no colour shift in flat brand colours, no softening of one-pixel borders. The resulting PDF is larger than a JPEG-based one would be, which is the correct trade when the content is text and line art.
The whole assembly runs in your browser through pdf-lib. Screenshots of internal dashboards or private correspondence never leave the machine you are sitting at.
A PDF page can hold an image in whatever compression it arrived with. When a PNG is added here without rotation, its existing lossless stream is embedded verbatim — the tool never rasterises it to a canvas, so there is no opportunity for quality to be lost. Zooming to 400% in a PDF reader shows exactly the pixels that were in the original file.
Two situations do trigger a redraw: rotating an image before building, and adding a WebP or HEIC file, since neither can be embedded directly by the PDF format. Those are re-encoded as JPEG at quality 0.95, which is high enough that the difference is not visible at normal viewing sizes but does mean a screenshot of small text is best added unrotated.
Yes. Unrotated PNG files are embedded with their original lossless compression intact, so text and thin lines in a screenshot are preserved exactly. Nothing is re-compressed on the way in.
The transparent regions are preserved in the embedded image, but a PDF page is white underneath, so transparent areas simply appear white when the document is viewed or printed.
Roughly the sum of your PNG files plus a small overhead, since the image data is copied rather than recompressed. If the result is too big to email, run it through Compress PDF, which rasterises pages at a lower quality to bring the size down.
Yes. Any combination of PNG, JPG, WebP and HEIC can be added to the same document, and each is embedded or converted according to what the PDF format allows.
Each page takes the dimensions of its own image at 96 DPI, so a 1920 × 1080 screenshot becomes a 1440 × 810 point page. Use Resize PDF Pages if you need uniform A4 or Letter output.
No. pdf-lib runs as JavaScript in this tab and builds the file in memory. No image data and no finished PDF is transmitted anywhere.