How to Prepare and Upload a Scan to Dotspotter for Yellow Dot Detection

To get a result from Dotspotter (forensicdots.de), print a mostly white page on a color laser printer, scan it at 600 dpi in color with 24-bit photo quality, save it as a JPG under 10 MB, then upload it and wait for the second image to appear. The tool only works on a scan of a physical printout — you cannot feed it a digital file that was never printed.

What you need before starting

• A color laser printer (the yellow tracking dot pattern is a printer artifact, so an inkjet or a black-and-white laser won't produce it).
• A scanner capable of 600 dpi color scans at 24-bit depth.
• A page whose content is mainly white, so the faint yellow dots aren't buried under ink.

Dotspotter provides a test sheet you can use: dotspotter-test-sheet.png (197 KB). Printing that template is the simplest way to keep the page mostly white.

Step-by-step

Step 1 — Print a mostly white page

Print a page on your color laser printer. The content should be mainly white; heavy graphics or photos can obscure the dot pattern. The provided template is designed for this.

Step 2 — Scan the printed sheet

Scan settings must be:

Deviating from these settings is the most common reason detection fails, because the dots are small and low-contrast.

Step 3 — Save as JPG

Save the scanned image as a JPG. Use a high-quality compression setting so you don't lose pixel information, but keep the file under 10 MB. If the file is too large, cut (crop) the picture rather than lowering quality.

Step 4 — Upload the image

Upload the JPG on the Dotspotter page. If the file is too big, do not decrease image quality or resize the image — cropping is the recommended way to reduce size, since resizing destroys the pixel detail the detector relies on.

Step 5 — Run DotSpotter and read the result

Start DotSpotter and check whether it finds the hidden dots on your image. The tool is finished when a second image appears on the right side. Depending on image size, processing can take up to several minutes, so don't assume it has stalled immediately.

Common problems and how to avoid them

• No dots detected: usually a scan-setting issue. Re-check 600 dpi, color, 24-bit, photo quality.
• File rejected for size: crop the image instead of resizing or recompressing at lower quality.
• Blurry or noisy scan: the dots are faint; a low-quality scan loses them before the software ever sees them.
• Wrong printer type: the pattern comes from color laser printers, so a printout from another printer type won't carry it.

What happens after upload

Results are shown on the same page. Dotspotter attempts to detect the yellow dot code (MIC) and displays a second image once processing completes. There is no indication in the available material that an account is required to upload, and PayPal appears as a payment platform on the site — but the material doesn't state which features are paid, so check the site directly if you hit a paywall.