Where: [ \textPixel Pitch (mm) = \frac\textField of View Width (mm)\textImage Width (pixels) ]
Take a picture at the exact same zoom/magnification setting as your sample. pixel value mm2
At 300 DPI, 1 mm equals approximately 11.81 pixels; at 96 DPI (typical screen rendering), 1 mm equals roughly 3.78 pixels. Where: [ \textPixel Pitch (mm) = \frac\textField of
For example, if your image's metadata states that one pixel is 0.005 mm wide (a pixel pitch of 5 µm), then the area of one pixel is (0.005 mm) * (0.005 mm) = 0.000025 mm² . The necessity of this conversion arises from the
The necessity of this conversion arises from the nature of digital sensors. A pixel is simply a sample of light information; it has no inherent size. A camera sensor with small pixels and a telescope with large pixels can both produce an image of the same resolution (e.g., $1920 \times 1080$ pixels), yet the physical area captured by each device is vastly different. Therefore, the relationship between a pixel and a millimeter is not fixed; it is defined by the or Pixel Size .
Sources: polotno.com
Using cv2.contourArea to find pixel areas, then multiplying by the squared scale factor.