What Is Dotspotter (forensicdots.de)?

Dotspotter is a free web tool at forensicdots.de that analyzes a scanned document to find the yellow tracking dots (Machine Identification Code, or MIC) that color laser printers add to every printed page. You print a mostly white test page on a color laser printer, scan it at 600 dpi in color, and upload the image; Dotspotter processes it and displays the detected dot pattern on the same page. It is aimed at anyone doing printer forensics or checking whether a document can be traced back to a specific device.

What the tool actually does

Many color laser printers encode a hidden pattern of tiny yellow dots on each page. The pattern can carry information such as the printer's serial number and the print date and time. The dots are nearly invisible to the eye but survive scanning, which is why forensic examiners use them to link a printed document to a machine.

Dotspotter automates the detection step. Instead of manually enhancing the yellow channel in image software, you upload a scan and let the site locate the MIC pattern for you.

How to use it

The workflow follows the site's own upload instructions:

1. Print a test page. Use a color laser printer and a page that is mainly white. The site provides a template, dotspotter-test-sheet.png (197 KB), which you can print for this purpose.
2. Scan the printed sheet. Set the scanner to 600 dpi, color mode, and photo quality (24-bit color depth).
3. Save as JPG. Use a high-quality compression setting so pixel information isn't lost, but keep the file under 10 MB. If the file is too large, crop the image rather than lowering quality or resizing.
4. Upload the image. Start DotSpotter and let it run.
5. Read the result. Dotspotter finishes when a second image appears on the right side. Depending on image size, processing can take up to several minutes.

Key constraints to plan around

The 600 dpi and 24-bit color requirements are not optional — the yellow dot pattern is low-contrast and small, so lower resolution or grayscale scans will typically lose the information the tool needs.

Practical notes

• Crop, don't downscale. If your scan exceeds 10 MB, the site recommends cutting the image instead of reducing quality or resizing, since either would destroy the pixel detail the detector relies on.
• Start with a clean test page. A mostly white page makes the faint yellow pattern easier to isolate than a page with heavy content.
• Expect a wait. Larger scans take longer; the result appears only after the second image renders.

What it is not

Dotspotter detects and displays the tracking pattern; it does not by itself decode the serial number or date into readable values for you. It is a detection aid for printer forensics, not a full forensic analysis suite. The site also lists Terms and Conditions, a Privacy Policy, and a contact page, and it accepts PayPal — but the upload instructions above are the core of what the tool does.