logprint-extractor 0.1.1

Extract depth-labelled borehole images from PDF well log prints.

logprint_extractor

A Python package for extracting depth-labelled PNG strips from PDF borehole image log prints.

Each page of the PDF is cropped to the log track and saved as a PNG whose filename encodes the top and bottom depth of that strip — the format required for import into WellCAD as an RGB image.

Contact [e-mail] for more information on extracting and using historic borehole image data.

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Installation

pip install logprint_extractor

Requires Python ≥ 3.11. Dependencies (pymupdf, Pillow, matplotlib) are installed automatically.

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Workflow

The extraction is a three-step process, each covered by a script in the tutorial/ folder.

Step 1 — Find pixel coordinates (tutorial/step1_find_pixel_range.py)

Use pxl_range() to interactively select the crop region on a rendered PDF page. Run this once for each distinct page layout (typically: first page, a representative middle page, and the last page).

1. A matplotlib window opens showing the rendered page.
2. Use the built-in zoom/pan tools to navigate to the area of interest.
3. Toggle Selection Mode on, then click the top-left corner of the log strip.
4. Press Accept Point to lock it in.
5. Navigate to the bottom-right corner, click, then press Accept Point again.
6. Close the window — the coordinate dict is printed to the terminal.
7. Copy the coordinates into steps 2 and 3.

Step 2 — Verify the crop (tutorial/step2_inspect_image.py)

Use inspect_image() to display the cropped region for the first, a middle, and the last page. Confirm the crop looks correct before running the full extraction.

Step 3 — Extract images (tutorial/step3_extract_image.py)

Use extract_image() to batch-process all included pages. Each page is saved as a PNG named with its depth range, for example:

FORGE_78B-32 224.70 - 228.65.png

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API reference

Function	Description
pxl_range(pdf_path, page_num)	Interactively define a crop rectangle and return pixel coordinates.
inspect_image(pdf_path, page_num, pixel_coords)	Display a single cropped page region for verification.
extract_image(pdf_path, output_dir, wellname, top_depth, base_depth, ...)	Batch-extract depth-labelled PNG strips from all included pages.

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Tutorial data

The tutorial scripts use an open-access FMI log print from the Utah FORGE project:

McLennan, J. (2021). Utah FORGE: Well 78B-32 Daily Drilling Reports and Logs. [Data set]. Geothermal Data Repository. Energy and Geoscience Institute at the University of Utah. https://doi.org/10.15121/1814488

The PDF (University_Utah_FORGE_78B-32_FMI_Interpretation_20.pdf) can be downloaded from https://gdr.openei.org/submissions/1330.