Notes

Npm tesseract.js

Support Format: bmp, jpg, png, pbm

The main Tesseract.js functions (ex. recognize, detect) take an image parameter, which should be something that is like an image. What's considered "image-like" differs depending on whether it is being run from the browser or through NodeJS.


On a browser, an image can be:
* an img, video, or canvas element
* a File object (from a file <input>)
* a Blob object
* a path or URL to an accessible image
* a base64 encoded image fits data:image/([a-zA-Z]*);base64,([^"]*) regexp


In Node.js, an image can be
* a path to a local image
* a Buffer storing binary image
* a base64 encoded image fits data:image/([a-zA-Z]*);base64,([^"]*) regexp
Each function is async

Tesseract.js is a JavaScript library
it supports more than 100 languages,
The + sign could be used to concatenate several languages as in eng+chi_tra

The logger property takes a function that will be called multiple times as Tesseract processes an image. The parameter to the logger function should be an object with workerId, jobId, status and progress as its properties:

Binarization is the conversion of the pixels of an image to either black or white. We want to binarize the previous gift card to check whether the accuracy will be better or not.

Previously, we extracted some texts from a gift card but the target PIN was not as accurate as we wanted. So there is a need to find another way to get an accurate result.

Now, we want to binarize the gift card, i.e. we want to convert its pixels to black and white so that we can see whether a better level of accuracy can be achieved or not.

The functions below will be used for binarization and it is included in a separate file called preprocess.js.