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Convert annotation formats

How to Convert Pascal VOC XML to COCO Run-Length Encoding RLE

In this guide, we show you how to convert data between the VOC and COCO RLE formats for free. You can use your converted data to train models and other models that support the COCO RLE format.

Pascal VOC XML

Pascal VOC is a common XML annotation format that is human readable but doesn't work with any known object detection models.

Below, learn the structure of Pascal VOC XML.

img0001.xml
<annotation>
	<folder></folder>
	<filename>000001.jpg</filename>
	<path>000001.jpg</path>
	<source>
		<database>roboflow.ai</database>
	</source>
	<size>
		<width>500</width>
		<height>375</height>
		<depth>3</depth>
	</size>
	<segmented>0</segmented>
	<object>
		<name>helmet</name>
		<pose>Unspecified</pose>
		<truncated>0</truncated>
		<difficult>0</difficult>
		<occluded>0</occluded>
		<bndbox>
			<xmin>179</xmin>
			<xmax>231</xmax>
			<ymin>85</ymin>
			<ymax>144</ymax>
		</bndbox>
	</object>
	<object>
		<name>helmet</name>
		<pose>Unspecified</pose>
		<truncated>0</truncated>
		<difficult>0</difficult>
		<occluded>0</occluded>
		<bndbox>
			<xmin>112</xmin>
			<xmax>135</xmax>
			<ymin>145</ymin>
			<ymax>175</ymax>
		</bndbox>
	</object>
</annotation>

COCO Run-Length Encoding (RLE)

A version of the COCO JSON format with segmentation masks encoded with run-length encoding.

Below, learn the structure of COCO Run-Length Encoding (RLE).

JSON
{
    "info": {
        "description": "Exported from Darwin",
        "url": "n/a",
        "version": "n/a",
        "year": 2022,
        "contributor": "n/a",
        "date_created": "2022/07/03"
    },
    "licenses": [
        {
            "url": "n/a",
            "id": 0,
            "name": "placeholder license"
        }
    ],
    "images": [
        {
            "license": 0,
            "file_name": "2020-02-09--20-26-30(GMT-0700)--18s.mkv-0005.png1920x1080.png",
            "coco_url": "n/a",
            "height": 1080,
            "width": 1920,
            "date_captured": "",
            "flickr_url": "n/a",
            "darwin_url": "https://darwin.v7labs.com/api/images/437470172/original",
            "darwin_workview_url": "https://darwin.v7labs.com/workview?dataset=484903&image=86",
            "id": 290,
            "tag_ids": []
        }
    ],
    "annotations": [
        {
            "id": 8944,
            "image_id": 290,
            "category_id": 8,
            "segmentation": [
                [
                    1550.78,
                    748.65,
                    1548.38,
                    770.21,
                    1638.96,
                    779.7,
                    1640.35,
                    757.28,
                    1640.83,
                    726.62,
                    1557.96,
                    718.72
                ]
            ],
            "area": 4641.607800000347,
            "bbox": [
                1548.38,
                718.72,
                92.44999999999982,
                60.98000000000002
            ],
            "iscrowd": 0,
            "extra": {}
        },
     ]
 }

Step 1: Create a free Roboflow public workspace

Roboflow is a universal conversion tool for computer vision annotation formats. The Public plan is the best way for those exploring personal projects, class assignments, and other experiments to try Roboflow. To convert your dataset, start by creating a free workspace on the Public plan.

Create Roboflow Workspace

Step 2: Upload your data into Roboflow

Once your account has been created, click Create New Project.

Roboflow's create project form, with Object Detection selected as the project type

Upload your data to Roboflow by dragging and dropping your Pascal VOC XML images and annotations into the upload space.

Roboflow's upload page, with a drag-and-drop area for images, annotations, videos and PDFs

Step 3: Generate Dataset Version

Next, click "Generate New Version" to generate a new version of your dataset:

Roboflow's Generate a Dataset Version page, showing the source images and train/test split for a new version

You can then apply any preprocessing or augmentation steps to your dataset:

The augmentation step of a new dataset version, with 90° Rotate and Brightness added

Step 4: Export Dataset Version

After generating, you will be prompted to Export your dataset. You can choose to receive your dataset as a .zip file or a curl download link. Choose COCO Run-Length Encoding (RLE) when asked in what format you want to export your data. You will see a dropdown with various options like this:

Roboflow's Download dialog, with the export format list open and COCO highlighted

Congratulations, you have successfully converted your dataset from Pascal VOC XML format to COCO Run-Length Encoding (RLE) format!

Video Tutorial

Convert Computer Vision Annotation Formats Tutorial

Want to dive deeper into converting annotation formats with Roboflow? In the tutorial below, we explore how to convert your data in the Roboflow dashboard. We also discuss rejecting annotations and train-test-validation splits.

Frequently Asked Questions

Yes! It is free to convert Pascal VOC XML data into the COCO Run-Length Encoding (RLE) format on the Roboflow platform.

If you have between a few and a few thousand images, converting data between these formats will be quick. But, the time it takes to convert between data formats increases with the more images you have.

Show guide

Convert Pascal VOC XML to other formats

Convert other formats to COCO Run-Length Encoding (RLE)

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