Units of image annotations

The units the x, y, width and height of image annotations are provided in percentages of overall image dimension.

Use the following conversion formulas for x, y, width, height:

{% codeblock lang:python %}
pixel_x = x / 100.0 * original_width
pixel_y = y / 100.0 * original_height
pixel_width = width / 100.0 * original_width
pixel_height = height / 100.0 * original_height
{% endcodeblock %}

For example:

{% codeblock lang:python %}
task = {
"annotations": [{
"result": [
{
"...": "...",

            "original_width": 600,
            "original_height": 403,
            "image_rotation": 0,

            "value": {
                "x": 5.33,
                "y": 23.57,
                "width": 29.16,
                "height": 31.26,
                "rotation": 0,
                "rectanglelabels": [
                    "Airplane"
                ]
            }
        }
    ]
}]

}

convert from LS percent units to pixels

def convert_from_ls(result):
if 'original_width' not in result or 'original_height' not in result:
return None

value = result['value']
w, h = result['original_width'], result['original_height']

if all([key in value for key in ['x', 'y', 'width', 'height']]):
    return w * value['x'] / 100.0, \
           h * value['y'] / 100.0, \
           w * value['width'] / 100.0, \
           h * value['height'] / 100.0

convert from pixels to LS percent units

def convert_to_ls(x, y, width, height, original_width, original_height):
return x / original_width * 100.0, y / original_height * 100.0, \
width / original_width * 100.0, height / original_height * 100

convert from LS

output = convert_from_ls(task['annotations'][0]['result'][0])
if output is None:
raise Exception('Wrong convert')
pixel_x, pixel_y, pixel_width, pixel_height = output
print(pixel_x, pixel_y, pixel_width, pixel_height)

convert back to LS

x, y, width, height = convert_to_ls(pixel_x, pixel_y, pixel_width, pixel_height, 600, 403)
print(x, y, width, height)
{% endcodeblock %}