Slightly different images give different results

[Lilian Sueiro Pedroso]

Hello, 

I am using Tesseract for c++, version 3.02

My init is like this: 

api = new tesseract::TessBaseAPI();

auto result = api->Init(path.c_str(), "eng", classifierToEnum(clasifier),configs, configs_size,&pars_vec,

&pars_values, false);

api->SetPageSegMode(tesseract::PSM_AUTO);

api->SetVariable("tessedit_char_whitelist", "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890abcdefghijklmnopqrstuvwxyz-.,:\"=@/#'+%&;*");

this->api->SetVariable("classify_enable_learning", "0");

this->api->SetVariable("classify_enable_adaptive_matcher", "0");

The result for this images is different, and the only difference between the image is the size of the background. 

Can someone help me to understand what is happening?