# Term to express a range of fluctuation

I am trying to make a term for a function equipped on an image sensor. The term is to express "the upper limit of fluctuation allowance in image size which is specified in %"

The value of percentage does not express the ratio of the enlarged image size compared to the original image size, so for example, 150% does not mean that the sensor will only detect a 150% bigger image to the original image.

Instead, it is to express the range of percentage of size fluctuation for sensor to accept to detect the shape (image) which makes 150% to mean that the sensor will detect an upscaled original image in all upscaling rate from 101% to 150%, such as a 102%, 117%, or 142% bigger image to the original image.

Does any of the followings describe the concept well? If not, what is the problem?

• Maximum size fluctuation allowance percentage
• Maximum size volatility allowance percentage

Or,

• Size fluctuation allowance percentage upper limit
• Size volatility allowance percentage upper limit

Or, maybe "percentage" better be "rate"? Also, all of the candidates seem redundant. Any term to combine some words?

Thank you in advance.

• How about "Image rescaling detection cap"? – Dan Bron Feb 19 '15 at 11:06
• Maximum Scaling Factor? – Marv Mills Feb 19 '15 at 11:25
• @Dan, does "cap" stand for "upper limit"? Is it used commonly? If so, it is a good term to know for me. – Jun Kyoto Feb 20 '15 at 0:09
• @Marv, when I look up "scale factor" on Wikipedia, it says it is "coefficient". Does it also imply "range"? Because the substance of the concept of what I am trying to explain is "limit of range (allowance)". – Jun Kyoto Feb 20 '15 at 0:10
• @Jun Yes, it does, and it is common. – Dan Bron Feb 20 '15 at 0:13

## 1 Answer

A rather technical term may be maximum absolute deviation

"The maximum absolute deviation around an arbitrary point is the maximum of the absolute deviations of a sample from that point."1

In your case, that point should refer to the true value. For example, your image sensors is applied on something of size 10, it measures 15, then the absolute deviation for that measurement (measurement implies comparing with true value) is |15-10|=5.

You also distinguish between upper and lower deviations. You might replace absolute by upper and lower to indicate that. An example of that is done engineering:

"Upper deviation: the difference between the maximum possible component size and the basic size."2

"Lower deviation: the difference between the minimum possible component size and the basic size."2

So you would use maximum upper deviation and maximum lower deviation.

Of course you could always express this percentually, you could then speak of maximum upper percent deviation and maximum lower percent deviation, 'percent deviation' is also use here3.