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This draws a mark on each page: either text you type or an image you drop alongside the document. Drawing over the existing content appends to each page and leaves links, form fields and annotations intact; drawing behind it has to recompose the page, which does not. The default is 20 percent opacity at -45 degrees through the centre.

Use it when the status of a document matters as much as its contents: a DRAFT that must not be quoted, a CONFIDENTIAL circulation, a SAMPLE for a prospective client, or photographs going out with your studio name across them.

วิธีทำงาน

1. Drop the PDF onto this page. For an image watermark, drop the PNG or JPEG alongside it.
2. Choose text or image, and type the wording if it is text.
3. Set the position, angle and opacity. Below about 25 percent the document underneath stays comfortable to read.
4. Turn on Tile to repeat a text mark across the page, which is far harder to crop away.
5. Choose whether the mark goes over the content or behind it, and give a page range if only some pages need it.
6. Press Add watermark and the download starts.

Over and behind are not two settings of the same thing. Drawing over appends to the page's existing content stream, so the page object survives and every link, annotation and form field on it survives with it. A content stream can only be appended to, so drawing behind means recomposing the page with the mark underneath and the original content drawn back on top - which leaves the old page object, and everything attached to it, behind. If the document has fillable fields you care about, stamp over and lower the opacity instead.

Behind has a second catch: it shows through only where the page is transparent. Many documents paint an opaque white rectangle across the sheet before drawing anything else, and a mark under that is a mark nobody will ever see. If behind produces a blank-looking result, that is why.

Tiling repeats a text mark across the page, spaced at six times the type size horizontally and four times vertically, so it reads as a pattern rather than a grey wash. A tiled mark ignores the position setting, since it covers the whole sheet, and it is clipped at the page edge. Tiling applies to text only; an image is placed once.

An image watermark is placed at its natural size, reading its pixels at 96 per inch - the same assumption Image to PDF makes, so a logo lands the same size in both tools. Rotation and opacity apply to it as they do to text, and PNG transparency is kept: a logo in a white square looks like a mistake. The image, like the document, is read from your disk and never sent anywhere.