The size of coins is understandable, intuitive, only to those people,
who use the coins. An "average" European probably does not
know, ho big the Chinese coins or the Japanese coins are.
People from outside of Europe probably do not have an intuitive
understanding, how big the various Euro-coins are.
The fix: when creating new photos, use a plain
ruler in stead of coins and write the units of the ruler
with a marker on the ruler.
May be one option might be that the "1cm" reference line or square
might be added to the PCB silkscreen graphics of newly designed PCBs.
The size of coins is understandable, intuitive, only to those people,
who use the coins. An "average" European probably does not
know, ho big the Chinese coins or the Japanese coins are.
People from outside of Europe probably do not have an intuitive
understanding, how big the various Euro-coins are.
The fix: when creating new photos, use a plain
ruler in stead of coins and write the units of the ruler
with a marker on the ruler.
May be one option might be that the "1cm" reference line or square
might be added to the PCB silkscreen graphics of newly designed PCBs.