Trying to get features for a symbol

[Paul]

Hello everyone,

I am trying to get a symbol's features by using the C API so I can create additional ways for debugging Tesseract.

Can anybody provide me with an example on how to use the following method?

TESS_API void  TESS_CALL TessBaseAPIGetFeaturesForBlob(TessBaseAPI* handle, TBLOB* blob, INT_FEATURE_STRUCT* int_features,
                                                       int* num_features, int* FeatureOutlineIndex);

As far as I understand it, I need to provide an INT_FEATURE_STRUCT that will hold the resulting features of the symbol after calling the method, as well as an int*, which will hold the number of features. What goes in FeatureOutlineIndex and which TBLOB* do I have to provide? How to I get it?

Or is there another method that can give me the features of a symbol?

Best regards,

Paul

[Paul]

I found out the following:

• int_features should be an array of length 512,
• num_features tells us how many features are really in int_features
• FeatureOutlineIndex holds the index of the corresponding outline for each feature in int_features

TESS_API TBLOB*
               TESS_CALL TessMakeTBLOB(Pix* pix);

will give us the TBLOB* needed for TessBaseAPIGetFeaturesForBlob(). If you want to get the Pix* for every symbol, simply call TessPageIteratorGetImage() or TessPageIteratorGetBinaryImage() while iterating over the symbols.

Now I still need to know how to get the features for prototypes...

[Paul]

Is there a method in the public API that allows me to gather the information from normproto or inttemp?

[zdenko podobny]

Maybe this will help you[1].

[1] https://groups.google.com/forum/?utm_medium=email#!msg/tesseract-dev/EYOfbGXiiIc/JtjB8q4lMjcJ

Zdenko

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[Paul]

Thank you for the link, Zdenko. Since I also want to get the features from ready-to-use traineddata files, that don't come with box/tr files, I started using the methods in tessdatamanager.h and intprotos.h.

Do you know how the features in tr files differ from the data in the intproto section of a traineddata file? I know that intproto mainly contains the 4D (x, y, angle, length) information.

There are four sections for each box in a tr file: mf, cn, if and tb. if seem to be the 3D int features (x, y, angle), but what do the features at mf, cn and tb mean?

Paul

[zdenko podobny]

Paul,

I never play with that, so I suggest you to update/continue at that thread...

Zdenko

To view this discussion on the web visit https://groups.google.com/d/msgid/tesseract-ocr/fbef68ce-3b65-4ff7-b0db-161e62c78c30%40googlegroups.com.