Pick the resolution deliberately: 150 DPI for screens, 300 for printing. Higher numbers give you larger files and little visible improvement at normal viewing size.
Use PNG for pages of text and diagrams, JPG for pages that are mostly photographs. JPEG artifacts cluster around sharp edges, which is exactly what text is made of.
Converting a PDF to images comes up whenever a page needs to go somewhere that does not accept PDFs. A slide deck, a web page, a social post, a support ticket, a print shop that wants flat files. It is a routine export with two settings that people usually leave alone and should not.
What you give up
A PDF page is mostly instructions: draw this glyph here, in this font, at this size. Those instructions are resolution independent, which is why a PDF looks sharp whether you view it at 50 percent or 400 percent, and why its text can be searched, selected and read aloud.
An image is a fixed grid of pixels. Converting a page to one executes those instructions once, at one resolution, and keeps the result. Everything that made the page flexible is gone.
- Selectable textBecomes pixels
- SearchNothing left to find
- HyperlinksPainted, not clickable
- Screen reader accessNo text to read
- Scaling without blurFixed at export DPI
- File sizeUsually much larger
Choosing a resolution
DPI decides how many pixels each inch of page becomes. It is the single most consequential setting and the one most often left at whatever the tool suggested.
Sharp on any display. An A4 page becomes roughly 1240 by 1750 pixels.
The standard for print reproduction. Four times the pixels of 150.
For reproduction of the original. Files get very large very quickly.
The arithmetic is worth internalising, because it is not linear. Doubling DPI quadruples the pixel count and therefore roughly quadruples the file size. Going from 150 to 600 makes each page sixteen times larger, and at normal viewing size a screen shows little of the difference.
PDFslime's PDF to Images offers 72, 150 and 300 dpi, exports PNG, JPG or WEBP in colour or greyscale, and takes a page range such as 12 or 1-3, 7, so you export only the pages you need.
PNG or JPG
The two formats compress in fundamentally different ways, and the right choice follows from what is on the page.
For text, diagrams and screenshots
- Lossless, so no artifacts anywhere
- Sharp edges stay sharp
- Handles large flat areas of colour efficiently
- Supports transparency
- Larger files for photographic pages
For pages that are mostly photographs
- Much smaller files for photographic content
- Quality setting trades size against fidelity
- Visible artifacts around text and line art
- No transparency support
- Wrong choice for a page of prose
When rasterising is the right answer
Given what it costs, it is worth being clear about when it helps. There are several cases where turning a page into an image is exactly correct.
Anywhere that does not accept PDFs at all: image fields in web forms, social media, chat applications, slide decks. Anywhere a page needs to become a thumbnail or a preview. And occasionally as a deliberate flattening step, when a page must be stripped of every interactive element and hidden layer, accepting the loss of searchability as the price.
Practical notes
A few things that come up once you are exporting more than a page or two.
Export a range, not the whole file. If you need page twelve, export page twelve rather than 200 pages of 300 DPI images you will delete.
Check the widest page. Documents with mixed page sizes produce images with mixed dimensions, which matters if they are going into a layout that expects consistency.
Watch the total at high DPI. An A4 page at 600 DPI is about 35 million pixels, so export one page first, check its size, and multiply by the page count.
Keep the PDF. It is the only version that can still be searched, and the only one you can re-export from at a different resolution.
Export PDF pages as images
Every page as PNG or JPG, at the resolution you choose. Nothing leaves your browser.
Common questions
Choosing settings you will not regret.
01What DPI should I use?
150 for a screen and 300 for print. If a page will be zoomed into on a high-resolution display, 300 keeps small text sharp there too. PDFslime's PDF to Images stops at 300 and limits any page to 40 million pixels, so a 600 DPI archival copy of a large page needs desktop software.
02Should I export as PNG or JPG?
PNG for pages of text, diagrams or screenshots, because it is lossless and keeps sharp edges clean. JPG for pages that are mostly photographs, where it is far smaller. JPEG artifacts cluster around hard edges, which makes it a poor choice for prose.
03Can I convert the images back into a PDF?
You can wrap them in a PDF, but the result is a document of pictures rather than the original. The text is no longer text, so it cannot be searched or selected unless you run OCR, which reconstructs it approximately and with errors.
04Why are my exported images so large?
Because of the resolution or the format. An A4 page at 150 DPI is around two million pixels, and a PNG of a page full of photographs stores every one of them losslessly. Switch that kind of page to JPG, or drop to 150 DPI if you chose 300.
05Why does the text look fuzzy in my exported images?
Either the DPI was too low for the size you are viewing at, or you exported as JPG and the compression put halos around the letters. For text-heavy pages, use PNG and at least 150 DPI.
06Does converting to images make a document more secure?
It removes selectable text, annotations and form data, so in that narrow sense yes. It also destroys accessibility and searchability for the whole document and usually increases the file size substantially. It is a last resort rather than a security measure.