Same photo getting different results for length! HELP!

I analyzed a set of photos last year and had no issues. I also had someone else do them and they got the same results.
I got another person to recently re analyze the photos and she came up with completely different results. After troubleshooting I realized when I re opened my photos I got the same as hers.
I am using the same scale etc.
After looking around I noticed that at the top of the photo the size of um was complexity different (43 vs 4300). The original images I was getting sizes of roughly 20-120 and now I am getting sizes of 4-15.

The screen shot i took from the photos from before at the top say “4437 X 3400 um (680/510)” and the new ones say “44 X 34 um (680/510)” So i know it has something to do with that i am just unsure what and why! I have tried everything! I know these new numbers are incorrect but I cant see what went wrong or how to fix it! HELP !


Do you mean the image properties (pixel width, height and depth) are the same?

Which file format are you using?

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This means the scale info embedded in the image is different. Maybe the software you used to capture the image has changed somehow?

To change the scale information you can use Analyze > Set Scale or Image > Properties.

You need to know the actual size of a pixel in um. If your previous scale was really correct (if your image shows a 4.4 x 3.4 mm area) then you can calculate:

4437 um/680 pixels = 6.525 um/pixel.
Dividing 3400/510 = 6.666 so that’s slightly different, but most cameras have square pixels. I’d guess there is a rounding error in your acquisition software.

You can confirm the scale by photographing a stage micrometer (are they microscope images?).

But more importantly, I don’t understand how your length measurements are off by a factor of 4-8 when your scale is off by a factor of 100. Can you share more info on the measurement process? (record a macro or share the procedure?)

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I finally figured it out! I had to set scale and put 1000 um. I rounded up for those measurements just to give the idea that they were off (those weren’t the EXACT numbers).
I know when I last did it I used a different number. I am not sure how but the scale was just mis measured this time around!
Thanks for the help!