PDF เป็นรูปภาพ

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Each page is redrawn as a grid of pixels at the resolution you choose and saved as a JPG, PNG or WebP. Because the page is rendered rather than exported, what you get is a picture of the page: text stops being text, and nothing in the image can be selected, searched or edited afterwards.

Reach for it when something needs a picture rather than a document: a page to drop into a slide, a diagram for a chat app that will not preview a PDF, or a proof for a print shop that asked for images at 300 dpi.

วิธีทำงาน

1. Drop the PDF onto this page. One file at a time, up to 300 MB.
2. Pick the format. JPEG suits scans and photographs, PNG suits text, diagrams and flat colour.
3. Set the resolution. 150 dpi is comfortable on a screen and 300 dpi is what a printer wants.
4. Give a page range if you only want part of the document, or leave it empty for every page.
5. Under advanced options, switch to grayscale or ask for a transparent background.
6. Press Convert to images. Each page arrives as its own file, and a ZIP is offered when there is more than one.

Resolution is the one decision here that really costs something. Doubling the DPI quadruples the pixel count: an A4 page at 150 dpi is about 2 megapixels, the same page at 600 dpi about 35. So each page is held to a ceiling of 40 megapixels and the scale is stepped down until it fits, and the result reports the resolution actually used - a request for 600 dpi that came back as 410 explains itself rather than turning up later as a soft print.

The three formats fail in different directions. JPEG is lossy and compresses photographic scans far better than anything else, but it smears the edges of small text; the quality slider runs from 40 to 100 and sits at 90, near the point where more quality mostly buys more bytes. PNG is lossless and keeps text and line art crisp, often at several times the size. WebP beats both at a similar quality, at the cost of older software that refuses to open it.

The conversion is one-way. Nothing in the image knows it was ever text, so a converted page cannot be searched or copied from, and running the images back through Image to PDF gives you a document of pictures rather than the file you started with. If you want the words, use PDF to text; if the problem is only that the file is too big to send, Compress PDF keeps the text alive in it.

Rendering happens on an OffscreenCanvas in a Web Worker, using the same PDF.js engine your browser uses to preview a PDF. Nothing is uploaded at any size, and once this page has loaded the tool keeps working with the network off. Files are numbered with leading zeros sized to the page count, so a 120-page document produces 001 through 120 and sorts correctly everywhere.