Automatic Document Scanning
Point your camera at any document. ScanFlow detects the edges, captures the image, corrects the perspective, and delivers a crystal-clear scan in under a second.
Intelligent edge detection
ScanFlow uses advanced computer vision to identify document boundaries in real time. As you hold your phone over a document, you will see a live overlay highlighting the detected edges. The algorithm distinguishes documents from the background surface, even when colors are similar, by analyzing contrast gradients and geometric patterns. This works with white paper on a white desk, receipts on textured surfaces, and business cards on cluttered tables.
The detection runs at camera frame rate, meaning there is no lag between moving the document and seeing the updated boundary. When the edges are stable and the document is fully in frame, ScanFlow captures automatically — no need to press a button.
Perfect geometry, every angle
Documents photographed at an angle appear trapezoidal in the raw image. ScanFlow's perspective correction algorithm transforms the captured quadrilateral back into a perfect rectangle, producing a scan that looks like it came from a flatbed scanner. The transformation is computed using a four-point homography matrix, ensuring precise geometric accuracy.
After perspective correction, the image is cropped to the exact document boundaries, removing any background. The cropping is sub-pixel accurate, so you never lose content at the edges and never see remnants of the desk or table surface in the final scan.
How auto scanning works
When you open the scanner, ScanFlow activates your device's camera and begins analyzing each frame for rectangular shapes. The edge detection system uses a combination of contour detection and line intersection analysis to find the four corners of your document. Once a stable quadrilateral is detected for several consecutive frames, the app captures a high-resolution image.
The captured image then passes through a multi-step processing pipeline. First, perspective correction straightens the document. Next, auto-crop removes the background. Then, image enhancement adjusts brightness, contrast, and sharpness to produce a clean, readable result. You can choose between color, grayscale, and black-and-white output modes depending on the document type.
For multi-page documents, ScanFlow keeps the scanner active after each capture. You can scan an entire stack of papers, a multi-page contract, or a full notebook, one page at a time. When you are done, all pages are assembled into a single multi-page PDF with consistent quality and formatting across every page.
The entire pipeline runs on-device. No images are uploaded to a server for processing. This means auto scanning works at full speed even without an internet connection, and your document images remain private.
Frequently Asked Questions
How does ScanFlow's automatic scanning work?
ScanFlow uses your device's camera and built-in machine learning to detect document edges in real time. When a document is recognized, the app automatically captures it, corrects the perspective, crops to the exact boundaries, and enhances the image for clarity. The entire process takes less than a second.
Can I scan multiple pages at once?
Yes. ScanFlow supports multi-page batch scanning. After capturing the first page, the app stays in scanning mode so you can continue scanning additional pages. All pages are combined into a single multi-page PDF document when you finish.
Does auto scan work with crumpled or angled documents?
ScanFlow's perspective correction handles documents photographed at angles up to approximately 45 degrees. The edge detection algorithm works well with slightly curved or creased documents. For best results, place the document on a contrasting surface and ensure adequate lighting.
Try auto scanning now
Download ScanFlow free and scan your first document in seconds.
App Store
iPhone & iPad
Google Play
Android
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