An image can look perfectly sharp on your screen but appear blurry, pixelated or soft in print. This is because screens and printers display images at very different resolutions — and a file that looks flawless in every digital preview can still get flagged or rejected the moment it hits a printing press.
Screen Resolution vs. Print Resolution
Screens typically display at 72–96 DPI (dots per inch). Print requires at least 300 DPI at the final output size. An image that fills a screen beautifully at 72 DPI will print at roughly one quarter of the required quality — the pixels simply aren't dense enough to reproduce fine detail on paper, where the eye is much closer and light doesn't pass through the image the way it does on a backlit screen.
DPI (dots per inch, sometimes called PPI — pixels per inch — for digital images before printing) measures how many individual pixels are packed into each inch of the final printed size. The same pixel dimensions can be "high resolution" or "low resolution" purely depending on how large you print them — a photo that's perfectly sharp as a small postcard can look pixelated blown up to poster size.
The Maths Behind DPI Requirements
To check if an image has enough resolution for a given print size, divide its pixel dimensions by the intended print size in inches. For example, an image that is 1500 × 1000 pixels, printed at 5 × 3.3 inches, gives 300 DPI — right at the minimum standard. The same image printed at 10 × 6.6 inches would only reach 150 DPI, which is visibly soft for anything with fine detail like text or thin lines, though it may pass for large-format prints viewed from a distance (posters, banners) where the eye is naturally further away.
This is why the same image file can be perfectly fine for a business card and completely inadequate for an A3 poster — resolution requirements scale with the physical print size, not just the pixel count in isolation.
Where Low-Resolution Images Come From
- Images downloaded from websites or social media (typically 72 DPI) — most platforms compress and downsize images automatically for faster loading, stripping out resolution you can't get back.
- Screenshots (screen resolution, not suitable for print) — a screenshot only ever captures at your screen's pixel density, which is far below print requirements even on a high-resolution monitor.
- Images exported from apps or presentations — PowerPoint, Keynote, and similar tools often compress embedded images on export to keep file sizes manageable.
- Logos saved as small PNG or JPG files — a logo saved once for a website header (often only a few hundred pixels wide) is rarely large enough for anything beyond small print use.
The Upscaling Trap
A common mistake is to upscale a low-resolution image to a larger size in Photoshop or a similar tool. This does not add real detail — software can only interpolate between existing pixels, guessing at colour values rather than recovering information that was never captured. The image will still look blurry in print, sometimes worse, since upscaling can introduce visible artefacts on top of the existing softness. The only genuine fix is to use a high-resolution source file, or in the case of logos and illustrations, to use a vector format that has no resolution limit at all.
AI upscaling tools have improved this somewhat in recent years — they can produce more convincing results than traditional interpolation for some image types — but they're still generating plausible detail rather than recovering real detail, and results vary significantly depending on the image content. For anything brand-critical or text-heavy, sourcing the original high-resolution file remains the only reliable option.
Find low-resolution images in your PDF
Upload your PDF and get an instant report on all images below 300 DPI.
Check resolution now →How to Check Image Resolution Yourself
On Mac: select the image file, press Cmd+I (Get Info) — pixel dimensions are listed under "More Info". Divide by your intended print size in inches to get the effective DPI.
On Windows: right-click the file → Properties → Details tab shows dimensions in pixels.
In Photoshop: Image → Image Size shows both pixel dimensions and the current resolution setting — make sure "Resample" is unchecked while checking, so you see the image's true native resolution rather than an interpolated value.
Directly in your PDF: the fastest way is to run the whole document through an automated preflight check, which flags every image below 300 DPI along with its exact location in the layout — rather than checking each image individually before placing it.
Best Practice
Use vector graphics (SVG, EPS, AI) for logos and illustrations whenever possible — they scale to any size without quality loss, because they're built from mathematical paths rather than a fixed grid of pixels. For photographs, always start from the highest-resolution original available; if you only have a low-resolution version, treat that as a hard limit on how large you can print it, not a problem to be solved with software.
A simple rule of thumb that avoids most resolution problems: request or shoot images at the largest resolution reasonably available, even if you only need a small version now. It's trivial to downsize a large image later; it's impossible to add real detail to a small one.
Frequently Asked Questions
Is 300 DPI always the right target?
300 DPI is the standard for most commercial print at typical viewing distances (brochures, flyers, business cards, magazines). Large-format prints viewed from further away — banners, billboards, posters — can look sharp at much lower DPI, sometimes as low as 100–150, because the viewing distance compensates.
Can I fix a low-resolution image with a filter or sharpening tool?
Sharpening can make edges appear slightly more defined but cannot recover missing pixel detail. It's a cosmetic adjustment, not a resolution fix, and applying it too aggressively can introduce visible haloing or noise.
Why does my image look fine in the PDF preview but get flagged as low resolution?
PDF viewers scale images to fit your screen, which can make a low-resolution image look deceptively sharp at reduced size. The actual pixel density only becomes visually obvious at full print size — which is exactly why an automated DPI check is more reliable than a visual check on screen.