Yes, with an if.
No, with a but.
It's pretty much impossible to do completely accurately from a single image. It's only even possible to do rough estimate from certain photographs and requires a lot of additional information, including reference points, known sizes, ability to prove something overlaps, etc...
You can come up with a pretty good estimate from exploiting parallax if you happen to have TWO images taken from different vantage points.
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But Mom, Pentax IS rebellious
Pentax K-7, K20D
Pentax SMCP-FA 35mm f/2.0 AL -- Pentax SMC 50mm f/1.7 -- Pentax DA 50-200mm f/4-5.6 ED -- Sigma 28-70mm f/2.8 EX DG IF Aspherical -- Pentax DA 18-55mm f/3.5-5.6 WR
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