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.

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.