pdf-look-scanned

# PDF Look Scanned Make PDFs look like physical scans with optional signature replacement. ## Dependencies ```bash pip3 install pillow pdf2image img2pdf numpy ``` Also requires `poppler` (provides `pdftoppm`): - macOS: `brew install poppler` - Ubuntu/Debian: `apt install poppler-utils` - Fedora/RHEL: `dnf install poppler-utils` - Arch: `pacman -S poppler` - Windows: `conda install -c conda-forge poppler` or download from [poppler releases](https://github.com/osber/poppler-windows/releases) ## Quick Start Run `scripts/make_scanned.py` for the core functionality. Read the script's `--help` for all options. ### Simple scan effect ```bash python3 scripts/make_scanned.py document.pdf ``` ### Adjust scan quality Lower DPI and quality = grittier, more realistic cheap-scanner look: ```bash python3 scripts/make_scanned.py document.pdf --dpi 150 --quality 75 --noise 7 ``` Higher DPI = cleaner scan, larger file: ```bash python3 scripts/make_scanned.py document.pdf --dpi 300 --quality 92 ``` ## Signature Replacement ### Finding signature coordinates Before replacing signatures, determine crop and placement coordinates. All coordinates are **fractions of page dimensions** (0.0-1.0). 1. **Convert the source PDF to images** and visually inspect to find the signature region 2. **Iteratively crop** to isolate just the signature ink (no text, no table lines) 3. **On the target PDF**, find the area to clear (old digital signature) and where to paste Use this Python snippet to explore coordinates interactively: ```python from pdf2image import convert_from_path from PIL import Image pages = convert_from_path("document.pdf", dpi=200) page = pages[0] # 0-indexed w, h = page.size # Crop a region and save for inspection crop = page.crop((int(w*0.5), int(h*0.4), int(w*0.8), int(h*0.6))) import tempfile, os crop.save(os.path.join(tempfile.gettempdir(), "crop_test.png")) ``` ### Replace one signature ```bash python3 scripts/make_scanned.py contract.pdf \ --sig-pdf signatures.pdf \ --sig-page 1 --sig-crop 0.41,0.33,0.62,0.42 \ --sig-target 25 --sig-clear 0.61,0.41,0.85,0.52 --sig-place 0.62,0.415 ``` ### Replace multiple different signatures Each set of `--sig-page`, `--sig-crop`, `--sig-target`, `--sig-clear`, `--sig-place` adds one replacement. They are matched positionally: ```bash python3 scripts/make_scanned.py contract.pdf \ --sig-pdf signatures.pdf \ --sig-page 1 --sig-crop 0.41,0.33,0.62,0.42 \ --sig-target 25 --sig-clear 0.61,0.41,0.85,0.52 --sig-place 0.62,0.415 \ --sig-page 2 --sig-crop 0.40,0.335,0.62,0.39 \ --sig-target 27 --sig-clear 0.61,0.635,0.85,0.72 --sig-place 0.60,0.655 ``` ### Signature parameters | Parameter | Description | |-----------|-------------| | `--sig-pdf` | Source PDF containing real signatures | | `--sig-page N` | Page number in source PDF (1-indexed) | | `--sig-crop L,T,R,B` | Crop box to extract signature (fractions) | | `--sig-target N` | Target page to replace signature on (1-indexed) | | `--sig-clear L,T,R,B` | Area to white-out old signature (fractions) | | `--sig-place X,Y` | Top-left position to paste new signature (fractions) | | `--sig-size F` | Signature width as fraction of page width (default: 0.11) | | `--sig-dpi N` | DPI for rendering source signature PDF (default: 350) | ## Scan effect parameters | Parameter | Default | Effect | |-----------|---------|--------| | `--dpi` | 200 | Render resolution. Lower = grittier | | `--quality` | 85 | JPEG compression. Lower = more artifacts | | `--noise` | 5.0 | Gaussian noise stddev. Higher = noisier | | `--blur` | 0.6 | Gaussian blur radius. Higher = softer | | `--rotation` | 0.7 | Max rotation in degrees | | `--contrast-min` | 0.88 | Min contrast (lower = more washed out) | | `--contrast-max` | 0.95 | Max contrast | ## Workflow for signature replacement When the user provides a PDF and a separate signature source: 1. **Check dependencies** are installed (`pillow`, `pdf2image`, `img2pdf`, `numpy`, `poppler`) 2. **Examine the source signature PDF** — convert to images, identify which pages have signatures 3. **Extract signatures** — iteratively crop to isolate the ink, verify no text bleeds in 4. **Examine the target PDF** — find pages with digital signatures, note the "Подпись:" or "Signature:" label positions 5. **Determine coordinates** — clear area must cover old signature without eating into labels; place position should be right after the label 6. **Run the script** with all parameters 7. **Verify output** — check signature pages visually, adjust coordinates if needed 8. **Check metadata** — run `exiftool` on the output to ensure no software traces remain Common pitfalls: - Crop box too tight: signature strokes get clipped on edges - Clear area too wide: eats into "Подпись:"/"Signature:" labels or surrounding text - Signature too large/small: adjust `--sig-size` (0.11 is typical for contracts) - Source PDF is a phone photo: use higher `--sig-dpi` (350+) and higher ink threshold