Key points at a glance
- Effective resolution depends on pixel dimensions and printed size.
- Changing a PPI label does not create missing image detail.
- Check photographs, charts and small labels separately.
Read pixel dimensions together with print size
A raster image contains pixels. Their density on paper depends on how large you place the image. PPI means pixels per inch; DPI more specifically describes output-device dots. For preparing the image, the effective pixel density at its intended size is the useful starting point.
Adobe identifies 300 PPI as a common benchmark for high-quality printing. It is not a blanket guarantee: the subject, original image quality and printing process also matter. Follow the agreed file requirements for the actual order.
Worked example: 1,800 pixels printed 15 centimetres wide
Divide pixel width by printed width in inches. One inch is 2.54 centimetres. An image 1,800 pixels wide, placed at 15 centimetres, has an effective resolution of approximately 305 PPI: 1,800 ÷ (15 ÷ 2.54).
At 30 centimetres wide, the same image provides only about 152 PPI. The file has not deteriorated; its information is spread across a larger area. A 900-pixel image placed at 15 centimetres also provides about 152 PPI.
Changing only the PPI value in file properties does not add original detail. Computational enlargement cannot reliably reconstruct missing labels or fix an out-of-focus photograph. Look for a better original or use a sensible smaller display size.
Treat charts differently from photographs
For a chart, the limiting factor is often its text. A screenshot may appear acceptable on screen but produce soft axis labels and thin lines on paper. Where possible, export from the original application in a suitable format and inspect the imported result in your document.
Vector graphics can describe lines and shapes without a fixed raster resolution. That does not help if the graphic contains a low-resolution bitmap internally or its labels export incorrectly. Also check whether the chosen format survives cleanly into the final PDF.
Check quality after export
Compare a demanding figure in the original document and the PDF. If it becomes blurred only during export, investigate image compression and output quality settings. Keep a high-quality source copy instead of repeatedly reducing the only version you have.
Do not judge solely by pixel edges at extreme zoom. Inspect the planned output size: are legends, symbols and source notes readable? A test page can reveal that a technically sharp chart still uses text that is too small. Select demanding pages containing photographs, line diagrams and tables before approving the full document.
Final submission context
Formal details can feel like a separate writing task, but they matter just as much for a printed submission. Anything missing, misplaced or inconsistently formatted in the document will also appear in the bound copy.
Use this guide together with your cover page, table of contents, page numbers, source notes and appendices. Prepare the final PDF for printing and binding only after the complete file has been checked.
Practical check before PDF export
- Do headings, chapter structure and page numbers match?
- Are sources, figures and tables included completely?
- Are required elements such as declarations, appendices or the cover page included where required?
- Did you open and check the final PDF after exporting it?
Checklist
- Pixel dimensions and intended print size are known.
- Figures use original files where possible.
- Axes and legends are readable at output size.
- PDF export has not visibly degraded the images.
- Demanding pages have received a focused check.
Common mistakes
- Looking only at the stored DPI label.
- Using screenshots when original graphics are available.
- Treating enlargement as recovery of original detail.
Your illustrations are ready for paper
Once photographs and charts are readable in the final PDF, select the printing format that fits your thesis.
Choose printing optionsRelated content
Explore related guidance on thesis structure, sources, formatting and final submission.
Frequently asked questions
Does every image need exactly 300 PPI?
No. It is a common starting point for quality raster printing. Subject matter, size, process and specific file requirements still matter.
Why does enlarging an image make it look softer?
The available pixels spread over a larger area. Effective resolution falls unless genuine additional image information is available.
Should I sharpen a blurry chart?
First look for a better export from the original application. Sharpening cannot reliably restore missing letters or fine lines.