VisionConverter

Index

• Description
• Installation
• How to Use
• Supported Formats
• License

Description

VisionConverter is a library for converting object detection annotation datasets between popular formats. It simplifies dataset interoperability for machine learning and computer vision projects.

Key Features:

• Bidirectional conversion between supported formats
• Unified internal representation ensures consistent and reliable transformations

Conversion Process:

1. Load the input dataset from the specified path
2. Transforms to internal representation
3. Convert from internal representation to target output format
4. Save the converted dataset to the desired output location

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Installation

Requirements

• Python >= 3.12
• Click >= 8.1.8
• Pillow >= 11.2.1

Install from Source

Clone the repository and install the package:

git clone https://github.com/GCousido/VisionConverter.git
cd VisionConverter
pip install  .

Development Installation

For development (including dependencies for testing) and in editable mode:

git clone https://github.com/GCousido/VisionConverter.git
cd VisionConverter
pip install -e ".[dev]"

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How to Use

Library Usage

You can use DatasetConverter as a Python library to convert datasets programmatically.

Example

from vision_converter import YoloFormat, YoloConverter, CocoFormat, CocoConverter, NeutralFormat

yolo_dataset: YoloFormat = YoloFormat.read_from_folder("./dataset/yolo")

internal_dataset: NeutralFormat = YoloConverter.toNeutral(yolo_dataset)

coco_dataset: CocoFormat = CocoConverter.fromNeutral(internal_dataset)

coco_dataset.save("./dataset/coco")

Command Line Interface

The CLI provides a simple interface for converting datasets:

Basic Usage

vconverter --input-format <INPUT_FORMAT> --input-path <INPUT_PATH> --output-format <OUTPUT_FORMAT> --output-path <OUTPUT_PATH> <OPTIONS>

Required Arguments

• --input-format: Source format
• --input-path: Path to the folder containing the input dataset
• --output-format: Target format
• --output-path: Path to save the converted dataset

Options

• --copy-images: Copy images files to the output directory.
• --symlink-images: Creates symbolic links to the original images in the output directory.

Examples

Convert a YOLO dataset to COCO:

vconverter --input-format yolo --input-path ./datasets/yolo --output-format coco --output-path ./datasets/coco

Convert Pascal VOC to YOLO:

vconverter --input-format pascal_voc --input-path ./datasets/pascalvoc --output-format yolo --output-path ./datasets/yolo

Convert COCO to Pascal VOC with images:

vconverter --input-format coco --input-path ./datasets/coco --output-format pascal_voc --output-path ./datasets/pascalvoc --copy-images

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Supported Formats

Format	Input	Output	Parameter Value	Description
YOLO	✅	✅	yolo	YOLO format (.txt files with normalized coordinates and classes.txt for class names)
COCO	✅	✅	coco	Microsoft COCO format (.json with absolute coordinates)
Pascal VOC	✅	✅	pascal_voc	Pascal Visual Object Classes format (.xml files with absolute coordinates)
CreateML	✅	✅	createml	Apple CreateML format (.json with centered bounding boxes and absolute coordinates)
TensorFlow CSV	✅	✅	tensorflow_csv	TensorFlow Object Detection CSV format (.csv with absolute coordinates)
LabelMe	✅	✅	labelme	LabelMe JSON format (.json files with shape annotations and optional embedded image data)
VGG	✅	✅	vgg	VGG Image Annotator format (.json with multiple shape types and region attributes)

Format Specifications

YOLO Format

• File Structure: One .txt file per image with same basename as the image
• Annotation Format: <class_id> <x_center> <y_center> <width> <height>
• Coordinates: Normalized values between 0 and 1 (relatives to the image size)
• Additional Files: classes.txt containing class names, one per line

EXPECTED INPUT FILE STRUCTURE                      GENERATED OUTPUT FILE STRUCTURE
      dataset/                                           dataset/
        ├── images/                                        ├── images/
        │     img1.jpg                                     │
        │     img2.jpg                                     │
        ├── labels/                                        ├── labels/
        │     img1.txt                                     │     img1.txt
        │     img2.txt                                     │     img2.txt
        │     classes.txt                                  │     classes.txt

COCO Format

• File Structure: Single .json file containing all annotations
• Annotation Format: JSON with images, annotations and categories arrays
• Coordinates: Absolute pixel values [x, y, width, height]
• Metadata: Includes dataset info, licenses, and category definitions

EXPECTED INPUT FILE STRUCTURE                      GENERATED OUTPUT FILE STRUCTURE
      dataset/                                           dataset/
        ├── images/                                        ├── images/
        │     img1.jpg                                     |
        │     img2.jpg                                     |   
        ├── annotations.json                               ├── annotations.json   

Pascal VOC Format

• File Structure: One .xml file per image, sharing the basename with the image file
• Annotation Format: XML structure with bounding box coordinates and class names
• Coordinates: Absolute pixel values <xmin>, <ymin>, <xmax>, <ymax>
• Metadata: Rich annotation metadata, including image size, object attributes (difficult, truncated, occluded), and source info

EXPECTED INPUT FILE STRUCTURE                      GENERATED OUTPUT FILE STRUCTURE
      dataset/                                           dataset/
        ├── JPEGImages/                                    ├── JPEGImages/
        │     img1.jpg                                     │     
        │     img2.jpg                                     │     
        ├── Annotations/                                   ├── Annotations/
        │     img1.xml                                     │     img1.xml
        │     img2.xml                                     │     img2.xml
        |-- ImageSets/                                     |-- ImageSets/

CreateML Format

• File Structure: Single .json file containing all annotations and an images/ folder with image files
• Annotation Format: JSON array with entries for each image, each containing image filename and annotations array
• Coordinates: Absolute pixel values with bounding boxes defined by center coordinates and dimensions {x_center, y_center, width, height}

EXPECTED INPUT FILE STRUCTURE                      GENERATED OUTPUT FILE STRUCTURE
      dataset/                                           dataset/
        ├── images/                                        ├── images/
        │     img1.jpg                                     │     
        │     img2.jpg                                     │     
        ├── annotations.json                               ├── annotations.json

TensorFlow Object Detection CSV Format

• File Structure: Single .csv file containing all annotations
• Annotation Format: CSV structure with specific columns for image metadata and bounding box coordinates
• Coordinates: Absolute pixel values <xmin>, <ymin>, <xmax>, <ymax>
• Required Columns: filename, width, height, class, xmin, ymin, xmax, ymax
• Features: Human-readable format, direct compatibility with TensorFlow Object Detection API, supports multiple objects per image

EXPECTED INPUT FILE STRUCTURE                      GENERATED OUTPUT FILE STRUCTURE
      dataset/                                           dataset/
        ├── images/                                        ├── images/
        │     img1.jpg                                     │     
        │     img2.jpg                                     │     
        ├── annotations.csv                                ├── annotations.csv

LabelMe JSON Format

• File Structure: One .json file per image containing annotations and image metadata
• Annotation Format: JSON with shapes array, each shape having label, points, shape_type, group_id, flags, and optional description
• Coordinates: Absolute pixel values for points defining shapes (e.g., polygons, rectangles)
• Image Data: Optional base64 encoded image data embedded in imageData field
• Metadata: Includes dataset version, flags, imagePath, imageHeight, imageWidth

EXPECTED INPUT FILE STRUCTURE                      GENERATED OUTPUT FILE STRUCTURE
      dataset/                                           dataset/
        ├── img1.jpg                                       ├── img1.jpg
        ├── img1.json                                      ├── img1.json
        ├── img2.jpg                                       ├── img2.jpg
        ├── img2.json                                      ├── img2.json

VGG Image Annotator Format

• File Structure: Single .json file containing all annotations with VIA metadata structure
• Annotation Format: JSON with _via_img_metadata containing image entries, each with regions array for shape annotations
• Coordinates: Absolute pixel values with support for 6 shape types: rect, circle, ellipse, polygon, polyline, point
• Shape Types:
  • Rectangle: {x, y, width, height} - top-left corner and dimensions
  • Circle: {cx, cy, r} - center coordinates and radius
  • Ellipse: {cx, cy, rx, ry, theta} - center, radii, and rotation angle
  • Polygon: {all_points_x[], all_points_y[]} - arrays of vertex coordinates
  • Polyline: {all_points_x[], all_points_y[]} - arrays of line point coordinates
  • Point: {cx, cy} - single point coordinates
• Metadata: Includes file_attributes for image-level data, region_attributes for annotation-level data, and optional VIA project settings

EXPECTED INPUT FILE STRUCTURE                      GENERATED OUTPUT FILE STRUCTURE
      dataset/                                           dataset/
        |-- images/                                        ├── images/
        |     img1.jpg                                     |
        |     img2.jpg                                     | 
        ├── annotations.json                               ├── annotations.json 

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License

This project is licensed under the MIT License - see the LICENSE file for details.