Help needed to find an app

So, im looking for an android app.
I dont know if this exists but if it does it will help me greatly.

When im looking at an image and I know one measurement, based on that measurement I need to work out all the other measurements within that image.

For example, im looking at bicycle image. I know that the top tube is 570mm long so by plotting that measument could there be an app that works out the other measurements?

X = 570
So
Y = ?

Any help to find this kind of thing would be fantastic, I know I could do this manually but it a massive headache on anything complicated

Many thanks in advance

a reply to: errorcode
I did a search for "picture distance measurement" on Google Play and quite a few apps came up. One was called ImageMeter and one was called Laser Distance Meter.

I hope this helps and you find what you are looking for.

a reply to: gator2001

Thanks I'll have a look.

a reply to: errorcode

For example, im looking at bicycle image. I know that the top tube is 570mm long so by plotting that measument could there be an app that works out the other measurements? X = 570 So Y = ?

This is a ratio and proportion problem of the form
"example X" is to "example Y" as R is to 100, solving for R
and then
"Your X" is to the "desired Y" as the Ratio(now known) is to 100, solving for Y

so, first solve to find R, the Ratio.

In the original image you need the 2 tubes that they show as a baseline and plug in those numbers.

Formula:

first, find the ratio of x to y in their model

eX R
--- ---
eY 100

Cross multiply example x with 100 and divide example y
into that number. This gives you the ratio (R)

same exercise now, substitution R and solving for Y

570 R
---- ---
Y 100

Cross multiply your X (570) with 100 and divide the Ratio ( R )
into that number, solving for Y

This gives you the Y value you want to use.