I took you 5 days to respond. You must of been burning up the web trying to concoct another post .
DPI is irrelevant in my calculations. I found values between 47 and 60. That corresponds pretty closely to the range of 1.5 to 2 cm. Assume 47 pixels = 1.5 cm. The photograph is 1851 pixels wide.
Then why did you post about the pixel size near the beginning of the text? Now it's the diameter of a cocoon that is the symbolic yardstick. By the way that jpeg resolution most likely was reduce down to the 300/ppi or there abouts. Which is the lowest you would want to go. There is that rule of thumb again. That is so the file becomes much smaller and allows ease of emailing. Large files create transmission problems, don't cha know. Internet providers have limits on file sizes that can easily be transmitted.
If KBLB had posted a much larger image, the measurements would be off by, at most, a pixel or two. Often the differences would be sub-pixel. That's not going to change the calculations appreciably.
Where do you come up with knowing that pixel ration is 47 to 1? Assumption no doubt. The jpeg is a digital representation taken most likely with an android or i-phone and there is appreciable doubt when it comes to your calculations. The pixel size can be one/cm or 1000/cm depending on the resolution that your software allows. And the cocoon pile is cropped!!! I'm repeating myself and starting to sound like you. Uncle for Christ's sake.....uncle.
You are clearly having trouble understanding me.
No not really. You sound educated. I assume that your mentor was Professor Irwin Corey. LOL