## Contrast ratio

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jcclq
Active User
Posts: 12
Joined: Thu Jul 22, 2021 1:05 pm

### Contrast ratio

Hi

I would like to create a mathematical function from 2 measurements. I managed to display the minimum (Min) and maximum (Max) of the waveform, but now I would like to display in real time the contrast ratio: (Max - Min)/(Max + Min).

I could not find in the manual how to do it, but is it possible?

Thanks a lot!

JC

Gerry
PICO STAFF
Posts: 1009
Joined: Mon Aug 11, 2014 11:14 am

### Re: Contrast ratio

Hi jcclq,

Are you referring to the Measurements at the bottom of the display?

Regards,

Gerry
Gerry
Technical Specialist

sbabic44
User
Posts: 3
Joined: Thu Nov 30, 2017 10:17 pm

### Re: Contrast ratio

Like this ?

(max(A)-min(A))/(max(A)+min(A))

you paste that in math line..

It will give you math waveform with that function...

jcclq
Active User
Posts: 12
Joined: Thu Jul 22, 2021 1:05 pm

### Re: Contrast ratio

Ok thanks Gerry, I'll try that.

Best regards
JCC

jcclq
Active User
Posts: 12
Joined: Thu Jul 22, 2021 1:05 pm

### Re: Contrast ratio

Hi

I created a new line in the math channel, but then I am not sure what to do. It does not seem to plot the formula (max(A)-min(A))/(max(A)+min(A)). I don't see anything in the bottom lines ('Measurements').

To refine my question: My signal is an oscillation of varying amplitude and DC level, which varies the value of min(A) and max(A), so also (max(A)-min(A))/(max(A)+min(A)). I would like to visualize this on the screen, either as a plotted signal vs time, or a value I could read.

Thanks
JC
Attachments
Math_channel.PNG (17.36 KiB) Viewed 3738 times

Gerry
PICO STAFF
Posts: 1009
Joined: Mon Aug 11, 2014 11:14 am

### Re: Contrast ratio

Hi jcclq,

Sorry I have been tied up doing other things.

After entering a Math formula, you need to
(a) set the Range and units correctly. If it is way too large the Math Channel will appear as a flat line, if it is way too small it won't appear at all (it will be out of range).
(b) Turn the Math channel on by ticking the check box for the newly created Math channel once you exit the editing windows.

If that still doesn't reveal the waveform, then the problem will be with the waveform (e.g. where it has been constant for a while there will be a value of zero, and where it crosses the zero line you will get -ve and -ve infinity either side of the zero point).

Regards,

Gerry
Gerry
Technical Specialist