How to Convert PDF Pages to Images Without Blurry Text

Render each page at 150 DPI for screens or 300 DPI for print, and pick PNG whenever the page is mostly text. That one choice does more for sharp letters than anything else, because PNG stores every pixel exactly and JPG does not.

Below are the numbers I measured on our own test pages, the exact settings the converter applies, and the three things that still make text look blurry after you have done everything right.

PNG or JPG: what the test pages showed

PNG is lossless. JPG is lossy: it throws away detail it expects you not to notice, and around the hard edges of letters that discarded detail shows up as faint smudges. MDN's image format guide covers the trade-off in depth, but one measurement says it faster.

I rendered two A4 pages through the same Ghostscript 10.08 command the converter uses. The text page has a heading, two short columns and a small ruled table. The photo page is mostly one large color photograph with a caption.

Two things surprised me. On the text page, PNG was not just sharper but 2.8 to 4.6 times smaller than JPG, because large white areas compress extremely well in a lossless format. On the photo page the usual rule held: JPG came in at 36 to 39 percent of the PNG size up to 300 DPI. At 600 DPI the two nearly met, because the embedded photo only held about 330 pixels per inch of real detail. Above that, Ghostscript was drawing smooth, enlarged pixels, and PNG handles smooth areas well.

So: text, tables, forms and diagrams go to PNG. Scans and photo-heavy brochures go to JPG. For a mixed page, convert both ways and zoom in on the smallest text before you choose.

Which DPI do you actually need?

A PDF stores page sizes in points, 72 to the inch. The image width in pixels is the page width in points, divided by 72, multiplied by the DPI you pick. An A4 page is 595.28 x 841.89 points; US Letter is 612 x 792.

Doubling the DPI doubles both sides, so the pixel count roughly quadruples. A single A4 page at 600 DPI is close to 35 million pixels. A slide shown on a 1920-pixel-wide screen gains nothing from that; the viewer scales it straight back down.

Converting a file in PDFCheck

1. Open PDF to Image and choose one PDF. Free accounts and guests can upload up to 50 MB; Pro and AI go to 100 MB.
2. Under Output Format, pick PNG ("Lossless, white background") or JPG ("JPEG compression").
3. Under Resolution (DPI), pick 72, 150, 300 or 600. The default is 150 DPI - Standard. The server accepts any whole number from 72 to 600 if you send one through the API.
4. Click Convert to Images. Ghostscript renders every page; a run stops after 300 seconds.
5. Preview the results. Files are named page_001.png, page_002.png and so on. Download them one at a time or click Download All (ZIP) for pdf_images.zip.

Two settings are fixed and worth knowing. PNG output uses Ghostscript's png16m device, so you get 24-bit RGB on a white background; transparent areas come out white, and there is no way to keep them see-through here. JPG output uses the jpeg device at quality 95, which keeps artifacts low at the cost of bigger files. Text and vector lines are anti-aliased with -dTextAlphaBits=4 and -dGraphicsAlphaBits=4, so edges are smoothed with in-between shades rather than left jagged. The Ghostscript device documentation describes both devices and the -dJPEGQ setting.

There is no page-range field. If you want three pages out of eighty, take them out first with Split PDF and convert the smaller file. That also keeps a long document away from the 300-second limit at 600 DPI.

Why does the text still look fuzzy?

• The DPI was too low for how big the image is shown. Convert again one step up. The PDF itself is untouched by conversion, so you can repeat it as often as you like.
• The page is a scan. Its text is already a picture. A higher DPI gives you a larger image of the same blur, because rendering cannot invent detail the scanner never captured.
• JPG artifacts are hugging the letters. Switch to PNG. On text pages it is the smaller file anyway.
• Something downstream resized it. Chat apps, slide tools and content systems recompress images on upload. Open the file you downloaded from the converter and check whether the blur is already there before blaming the conversion.

A related case: a photo inside the page looks softer than the original picture. The converter draws the whole page at your chosen DPI, so a photo printed small on the page gets few pixels. To get the picture at its stored resolution, use Extract Images instead. The guide on extracting images from a PDF explains the difference.

What a page image can no longer do

An image is a flat picture. Nobody can select, search or copy the text, and a screen reader has nothing to read. Links, form fields, bookmarks, attachments, accessibility tags and digital signatures do not carry over. Keep the PDF as your master copy and use the images for previews, slides, social posts and systems that refuse PDFs. If you publish page images on a web page, add alt text or link to the text version.

Doing it without PDFCheck

If you have Ghostscript installed, the command below produces the same kind of output as our 150 DPI PNG setting. The -r switch sets the resolution, as the Ghostscript usage guide describes:

gs -dBATCH -dNOPAUSE -sDEVICE=png16m -r150 -dTextAlphaBits=4 -dGraphicsAlphaBits=4 -o page_%03d.png input.pdf

Poppler's pdftoppm -png -r 150 input.pdf page does the same job with a different renderer, and on a Mac, Preview's Export command saves the page you are looking at as PNG or JPEG. None of these give you a batch preview or a ZIP, which is mostly what the web tool adds.

When the conversion fails

An error beginning Conversion failed: followed by Ghostscript output almost always means the PDF is password-protected or damaged. Remove a known password with the PDF password tool, or re-save the file from the program that made it, then try again.

Output is PNG or JPG only. There is no WebP, TIFF or SVG; if you need one of those, convert the PNG files afterwards in an image editor, since PNG loses nothing on the way.

On retention: the uploaded PDF is deleted as soon as the conversion finishes. The images and the ZIP are removed by an hourly cleanup once they are more than 24 hours old. The results page opens only in the browser session that made it, but a direct link to one image works for anyone who has it until that cleanup runs, so do not paste those links around if the pages are private.