DPI / Resolution

What is DPI / Resolution?

DPI stands for Dots Per Inch. It represents the density of ink dots that a printing press deposits on a physical surface. In digital design, this is closely linked to PPI (Pixels Per Inch).

While a screen can display images clearly at low resolution (often 72 or 144 DPI/PPI), printing requires much higher pixel densities to achieve sharp details and smooth gradients.

The Print Risk: Why Low DPI is a Problem

When a low-resolution image is printed, the printer has to stretch the available pixels over a larger physical area. This results in:

• Pixelation: Visible square pixels (blockiness) along edges.
• Blurriness: Smudged details, soft edges, and unreadable text.
• Artifacts: Visual noise and color bands in gradient areas.

The industry standard minimum resolution for high-quality commercial printing is 300 DPI at final size. You can test your images against this target with the free image DPI checker.

How Filecheck Handles DPI Checks

Filecheck evaluates all embedded raster images in uploaded PDFs:

1. Effective DPI Calculation: We measure the physical size of the image placeholder on the page against its actual pixel width and height. For example, a 1000px image placed at 2 inches wide has an effective resolution of 500 DPI.
2. Min-DPI Enforcement: If any placement falls below the configured threshold (default 300 DPI), Filecheck raises a warning or rejects the file.
3. Autofix & Downsampling: If an image has an excessively high DPI (e.g. 1200 DPI), it bloats the file size without adding print quality. Filecheck can automatically downsample the images to a standard 300-600 DPI limit, keeping file transfer and processing fast while maintaining crisp quality.