I've got a device I purchased which displays voltage, amperage, etc. for the connected device. I did not build the device, nor does the manufacture provide any type of interface or storage options. It simply displays "real-time" data on a small display.

I would like to store the data such that I can review/understand the time history. The easiest way I could think of doing this is to place a camera in front of the digital display, do some image processing to recognize the digits, then save the corresponding image timestamp and value to generate a time series.

I'm wondering if this solution already exists? If so, can you help steer me in the right direction? I've tried to search the internet, but it's hard to get the "key words" right to provide results specific to my application. I know there are tools for "image processing to recolonize the digits", but I'm not aware of any specific ones. Can you give some examples? I'm not looking for a full blown text interpreter...mainly just digits 0-9.

I can't think of any other way to do this, so I'm open to suggestions (assume I can't hack into the device).


Copying from here: RPi OCR or how to read a number from the camera

Answered by Ghanima

"I recently used Tesseract which is an OCR software that's open source and it gives highly accurate results.

To install it on pi, type in the command line:

sudo apt-get install tesseract-ocr

Then set a camera to periodically take pictures preferably using Cron (which schedules tasks) and fswebcam (takes pictures using USB cams) Save the pictures in a special directory and set (also using Cron) Tesseract to extract the text from the pic and output the text in a separate .txt file. Deal with the extracted text according to your preferences.

I know I didn't offer much but I hope I've given some general pointers"

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