hipp 0.0.3

Historical Image Pre-Processing

hipp

HIPP (Historical Image Pre-Processing) is a python library to pre-process scanned historical images for Structure from Motion surface reconstruction and photogrammetric analysis.

---

Features

Preprocessing of Aerial Images

• Fiducial Marker Detection

  • Built-in application to generate fiducial marker templates
  • Detection of fiducial marker coordinates using OpenCV template matching
  • Sub-pixel accuracy for fiducial detection
  • Supports detection of 4 midside and/or 4 corner fiducials
  • Replaces low-confidence matches with None, based on a matching score threshold
  • Estimates the principal point based on valid fiducials
  • Quality Control Outputs:
    • Cropped windows around detected fiducials for visual inspection
    • Distribution plots of principal point deviations and individual fiducial coordinates
    • Matching score distributions
    • RMSE of fiducial coordinates before and after affine transformation

• Fiducial Marker Proxy Detection (feature in development)

• Image Restitution

  • Computes the appropriate geometric transformation between detected and calibrated fiducial positions:
    • 1 point → Translation
    • 2 points → Similarity transformation
    • 3+ points → Affine transformation
  • Crops the image around the estimated principal point to a standard size
  • Applies CLAHE (Contrast Limited Adaptive Histogram Equalization) to enhance features for SfM (Structure from Motion)
  • Computes the full affine transformation matrix (including crop transformation)

See this notebook for example.

Preprocessing of KH-9 Panoramic Camera Satellite Images (feature in development)

• Image Joining (feature in development)

  • Joins split images into a single composite image
  • Requires input images named sequentially (e.g. ImageId_a, ImageId_b, ImageId_c, …)
  • A small overlap between image parts is required for proper stitching
  • Uses image_mosaic from the ASP toolkit

• Image Cropping (feature in development)

  • Built-in interactive tool to manually select corners of the region of interest
  • Rotates and crops the image to align the selected top edge horizontally

Preprocessing of KH-9 Mapping Camera Satellite Images (feature in development)

---

Installation

pip install hipp

License

hipp is distributed under the terms of the Apache-2.0 license.