# Uncertainties using Photoshop ruler tool?

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Hey guys, so I am using Photoshop to measure some things for my extended essay with the ruler tool.

However, I have been trying to think how to get the uncertainty of the tool as I need it to make the calculations and analyze the data. I have sent an email to my supervisor yet he has not responded me and even searched on the internet hoping that I would get some kind of idea or guide that would help me figure it out.... but nothing, and I have my draft due in a week!

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Im not sure exactly what the ruler tool on photoshop is, however, a ggod rule of humb is that the uncertaintity is either, the smallest digit, if the equpitment is digital, or 1/2 the smallest measurement if the equiptment is analogue.

For the photo shop tool, I assue it gives you a figure, as opposed to having an actual virtual ruler picture. If this is the case then the uncertaintity is the smallest digit. e.g. if you get a reading of 1.768cm, the uncertaintity is +/-0.001cm. or if the reading is 1.8cm, the uncertaintity is +/-0.1cm

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For the photo shop tool, I assue it gives you a figure, as opposed to having an actual virtual ruler picture.

The reason I am not sure is that, although it is "digital", I still have to define the boundaries (as in, I have to give the program where is the beginning and where is the end), which, in my opinion, kind of makes it into an analog instrument.

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I'd go with twice the lowest digit then. .001 for the lower bound and .001 for the upper bound therefore .002. (assuming it measures to 3dp). Does this make sence to you. I assume some one more experienced can confirm

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that makes sense! Thank you so much for your help! ^^

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