This is one of the most common and confusing traps in self-publishing. Here's exactly what's happening and how to actually fix it.
Check my PDF free →You did everything right. You exported your Canva design as a PDF for print, selected 300 DPI, and uploaded it to IngramSpark or KDP. Then BookReady — or IngramSpark itself — flagged one of your images as low resolution. But how? You just told Canva to export at 300 DPI.
Here's the thing: Canva's "300 DPI" export option sets the document's DPI metadata tag. It does not upsample, resize, or add pixels to any image you placed inside the design. Those are two completely different things.
When you upload an image into Canva, it arrives with a fixed number of pixels. Exporting "at 300 DPI" tells the PDF file to label itself as 300 DPI — but it cannot create pixels that don't already exist. If the image was low resolution going in, it is still low resolution coming out. The label changed. The pixels didn't.
DPI stands for dots per inch. It describes how many pixels are packed into each inch when an image is physically printed. A 300 DPI image at 5×5 inches has 1,500 × 1,500 pixels. A 72 DPI image at the same size has only 360 × 360 pixels — which would print blurry or pixelated.
Here's the critical part: DPI is a relationship between pixel count and physical size. If you have 360 pixels and you want 300 DPI, that image can only print sharply at about 1.2 inches wide. Stretch it to 5 inches, and your effective DPI drops to 72 — no matter what the PDF metadata says.
| Print Size | Pixels Needed at 300 DPI | Common Problem |
|---|---|---|
| 3 × 3 inches | 900 × 900 px minimum | Phone screenshots (~400×400 px) fall short |
| 4 × 6 inches | 1200 × 1800 px minimum | Canva stock images sometimes under this |
| 5 × 5 inches | 1500 × 1500 px minimum | Typical illustration — needs high-res source |
| Full page (6×9) | 1800 × 2700 px minimum | Background images often too small |
Many online DPI checker tools look for an embedded DPI tag inside the image file (stored in EXIF or IPTC data). When they say "no metadata" or "can't determine DPI," it means the image was saved without that tag — which happens all the time with PNGs exported from design software, files sent by artists, or anything saved from a phone or screenshot.
The absence of DPI metadata doesn't mean the image is definitely low resolution. It just means you can't use metadata alone to check. You need to look at the actual pixel dimensions and do the math against the physical print size.
BookReady doesn't rely on DPI metadata tags — it measures the actual pixel dimensions of each embedded image and calculates the effective DPI at the size it's placed in your document. That's why it catches low-res images even when Canva's metadata says 300 DPI.
Find out the actual pixel dimensions of your image. On a Mac, open the file in Preview and go to Tools → Adjust Size. On Windows, right-click the file, go to Properties → Details. Look for the pixel width and height.
Calculate the effective DPI. Divide the pixel width by the physical print size in inches. If your image is 800 pixels wide and prints at 5 inches, your effective DPI is 160 — well below the 300 DPI minimum.
Get a higher resolution source file. If a human artist created the image, ask them to re-export from their original file at 300 DPI at your print size. If it was created digitally in Procreate, Photoshop, or Illustrator, they can re-export at the correct settings. If it's a scanned drawing, rescan at 600 DPI.
Replace the image in Canva with the high-res version. Delete the old image from your Canva design and upload the new high-res file. Re-export your PDF for print.
Run it through BookReady again to confirm the resolution check passes before uploading to IngramSpark or KDP.
Tools like Topaz Gigapixel or Adobe's AI upscaling can sometimes recover detail from low-res images — but the results depend heavily on the original image. For line art and illustrations with fine detail like stippling or crosshatching, AI upscaling often introduces artifacts. It's worth trying as a last resort, but getting the original high-res source is always the better solution.
This issue doesn't only happen in Canva. Google Docs compresses images when you insert them — sometimes significantly. If you wrote your book in Google Docs and inserted illustrations or photos, Google may have silently reduced their quality on insert. This is one reason professional book formatters strongly recommend working in dedicated software like Affinity Publisher, InDesign, or Atticus when your book contains images.
Not really. No software can invent detail that wasn't in the original image. Upscaling tools can smooth out pixelation but they don't add real detail. For print books where sharpness matters, the only real fix is a higher resolution source file.
Screens display at 72–96 DPI. At that resolution, even a low-resolution image looks sharp. Print requires 300 DPI, so what looks fine on a 27-inch monitor can look blurry when printed at 4 inches wide. The screen is not a reliable judge of print quality.
BookReady calculates effective DPI from actual pixel dimensions at placed size, which is what IngramSpark measures. If a DPI checker is reading metadata only and getting a different answer, trust the pixel math. IngramSpark will catch it at upload.
IngramSpark requires 300 DPI minimum for grayscale and color images in interior PDFs. For covers, 300 DPI at the final cover dimensions including bleed. Line art and black-and-white illustrations can actually benefit from 600 DPI since fine lines reproduce better at higher resolution.
BookReady scans every image in your PDF and reports the exact DPI and pixel dimensions. Free to check. Pay $9 only if you want the fixed file.
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