Blood Swipe Reconstruction

A swipe is a bloodstain resulting from the transfer of blood from a blood-bearing surface onto another surface, with a relative motion between the two surfaces. In simpler words, swipes occur when a bloody object is rubbing along another object. If you have no crime scene pictures, swipe a bloody object along a white sheet of cardstock or thick paper.

Photograph the entire blood stain on a surface with a uniform white (or very light) background. Crop tightly around the blood stain — but keep the entire stain fully visible without cutting off any edges. Note the swipe direction, which our app will reconstruct.

For best results:

• Use a clean, uniform white background
• Resolution at least 500x200 pixels (higher is better)
• Avoid cluttered backgrounds and crops that cut off any part of the swipe

Examples (click to view full size):

Good example: good_image_4904.png — uniform white background, full swipe visible, resolution > 500x200 px

Bad example: bad_image_4912.png — non-uniform / cluttered background, crop too tight

These open in a new tab so they don't interrupt your current view.

The app determines what was the bloody object, and the direction it was swiped. The direction is determined by a red arrow. The app also provides confidence values between 0% and 100%. At the moment, our app has only been tested on uniformly white backgrounds. For best results, photograph swipes on white cardstock, paper, or wall. Do not trust any result with low confidence.

Research mode saves your image and the information on how you created the stain, to help us improve our app. It is half price because you are contributing that ground-truth data, so your submission is kept for 3 years - and indefinitely if it is used to train the classifier - and may be used (anonymised) to improve the classifier. Please enter accurate, good-faith ground truth only. Using research mode just to pay less, without a genuine contribution, may lead to a credit adjustment or loss of research access. If you are unsure, use standard mode.

Standard-mode images are automatically deleted 30 days after submission (your result and history entry remain, only the images are removed). Private-mode images are never stored at all. Research-mode submissions are kept for 3 years, or indefinitely if they are used to train the classifier. Full details are in our Data Retention Policy.