PrintVariables produces config file that ReadConfigFile does not properly read #3943

Balearica · 2022-10-15T03:06:26Z

Expected Behavior:

The API function PrintVariables prints current parameters to a file, and ReadConfigFile reads parameters from a file. Intuitively, ReadConfigFile should be able to read the files that PrintVariables writes. This is explicitly assumed within the ProcessPage function, where these functions are used together to "Save current config variables before switching modes" and then "Restore saved config variables".

tesseract/src/api/baseapi.cpp

Lines 1293 to 1306 in a873553

    
           // Save current config variables before switching modes. 
        
           FILE *fp = fopen(kOldVarsFile, "wb"); 
        
           if (fp == nullptr) { 
        
             tprintf("Error, failed to open file \"%s\"\n", kOldVarsFile); 
        
           } else { 
        
             PrintVariables(fp); 
        
             fclose(fp); 
        
           } 
        
           // Switch to alternate mode for retry. 
        
           ReadConfigFile(retry_config); 
        
           SetImage(pix); 
        
           Recognize(nullptr); 
        
           // Restore saved config variables. 
        
           ReadConfigFile(kOldVarsFile);

Current Behavior:

Unfortunately, this does not currently work properly. The issue is that PrintVariables prints parameter descriptions alongside key/value pairs (e.g. chs_trailing_punct1 ).,;:?! 1st Trailing punctuation), and ReadConfigFile reads the description as a value (for string parameters). An example showing this is below.

#include <tesseract/baseapi.h>

int main()
{
    tesseract::TessBaseAPI *api = new tesseract::TessBaseAPI();
    if (api->Init(NULL, "eng")) {
        fprintf(stderr, "Could not initialize tesseract.\n");
        exit(1);
    }

    static const char *kOldVarsFile = "failed_vars.txt";

    // Print default value of chs_trailing_punct1
    printf("Initial value: %s\n", api->GetStringVariable("chs_trailing_punct1"));
    FILE *fp = fopen(kOldVarsFile, "wb");
    api->PrintVariables(fp);
    fclose(fp);
    api->ReadConfigFile(kOldVarsFile);
    printf("After PrintVariables/ReadConfigFile: %s\n", api->GetStringVariable("chs_trailing_punct1"));

    api->End();
    delete api;
    return 0;
}

This returns the following:

Initial value: ).,;:?!
After PrintVariables/ReadConfigFile: ).,;:?!	1st Trailing punctuation

The impact of this is:

ProcessPage does not work correctly when used with retry_config
There is no simple interface for generating a config file with the user's current settings
1. This is useful for saving/restoring configurations (as ProcessPage attempts to do)

Suggested Fix:

The simplest solution would be to remove the descriptions from the PrintVariables output (or at least hide that behavior behind an option). I can write a PR if others agree this makes sense. Editing ReadConfigFile to ignore the descriptions is likely also possible, but could be higher effort.

Environment

Tesseract Version: 5.2.0
Commit Number: 15200c6
Platform: Linux ubuntu 5.15.0-43-generic

The text was updated successfully, but these errors were encountered:

amitdo · 2022-10-15T16:38:59Z

The simplest solution would be to remove the descriptions from the PrintVariables output

We don't want to do this because that function is used by the command line tool and we need the descriptions in that case.

tesseract/src/tesseract.cpp

Lines 721 to 724 in 0daf18c

    
           if (print_parameters) { 
        
             FILE *fout = stdout; 
        
             fprintf(stdout, "Tesseract parameters:\n"); 
        
             api.PrintVariables(fout);

Balearica · 2022-10-15T20:51:45Z

@amitdo Good point. How about adding an option to PrintVariables for whether info text should be included (enabled by default, but disabled for the call within ProcessPage).

amitdo · 2022-10-16T06:24:21Z

How about using:

if (fp == stdout)

or:

(fp == stdout) ? ... : ...

in:

tesseract/src/ccutil/params.cpp

Line 164 in 60fd2b4

void ParamUtils::PrintParams(FILE *fp, const ParamsVectors *member_params) {

…ct-ocr#3943

Balearica · 2022-10-19T03:37:37Z

@amitdo Works for me. Added PR #3947.

I confirmed (1) running tesseract --print-parameters from the command line still prints the info text and (2) the issue demonstrated in the example above is resolved (the value of chs_trailing_punct1 is not changed).

stweil · 2022-10-19T06:01:51Z

The regression was added in c51691f in 2014, a long time ago, so all relevant releases are affected.

stweil · 2022-10-19T06:09:59Z

Obviously the argument retry_config for the API functions ProcessPages and ProcessPagesFileList which triggers the regression was not used for years. Is it useful? If not, we simply might drop the support for it.

If retry_config is useful, maybe the regression could be fixed by extending ParamUtils::ReadParamsFromFp to remove the comment part from the input lines. Or even better, TessBaseAPI::ProcessPage should save and restore parameters in memory without any file on disk.

Balearica · 2022-10-19T07:00:39Z

I think the ability to dump the user's current parameters and easily restore them later is useful (we're implementing a feature in Tesseract.js that tries to do this using PrintVariables/ReadConfigFile).

Adding a new function that writes a config file without the info text (suggested in the PR #3947) seems like an easy and effective solution. I looked into whether ReadConfigFile could be tweaked to ignore the info text, however this seems potentially tricky/error-prone. My first thought was to read everything to the first space character as the parameter value, however at least one parameter uses space character(s) as values (the default value of page_separator is \n).

amitdo · 2022-10-19T07:27:59Z

I think the ability to dump the user's current parameters and easily restore them later is useful

Related issue: #3260

stweil · 2022-10-19T08:00:45Z

I looked into whether ReadConfigFile could be tweaked to ignore the info text, however this seems potentially tricky/error-prone. My first thought was to read everything to the first space character as the parameter value, however at least one parameter uses space character(s) as values (the default value of page_separator is \n).

ParamUtils::PrintParams uses KEY TAB VALUE TAB COMMENT.

amitdo · 2022-10-19T08:55:38Z

#3670 (comment)

This comment and my comments below it are also related to this issue.

Balearica · 2022-10-20T02:05:56Z

ParamUtils::PrintParams uses KEY TAB VALUE TAB COMMENT.

Okay, if we are confident that VALUE will never include tabs, then I can edit ReadConfigFile to only read until the first tab. If this is not the case, then I can do the separate DumpParameters function.

Balearica · 2022-11-04T03:58:13Z

@stweil Do you believe it's safe to assume that tabs will not be used as parameter values (so it is safe for ReadConfigFile to read everything up to the tab and ignore everything after)?

Balearica · 2023-05-10T02:43:57Z

I created a new PR (#4074) based on @stweil's idea to implement by adding a new function in #3947 (review).

amitdo added the regression label Oct 18, 2022

Balearica pushed a commit to scribeocr/tesseract that referenced this issue Oct 19, 2022

Updated PrintParams to no longer print info text to files per tessera…

03be197

…ct-ocr#3943

Balearica mentioned this issue Oct 19, 2022

Updated PrintParams to not print info text to config files per #3943 #3947

Closed

GerHobbelt mentioned this issue Feb 25, 2023

RFC: ParamUtils::ReportParamsUsageStatistics(): report the tesseract variables actually used during the current run. #4021

Open

Balearica linked a pull request May 10, 2023 that will close this issue

Fix code for generating config files #4074

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PrintVariables produces config file that ReadConfigFile does not properly read #3943

PrintVariables produces config file that ReadConfigFile does not properly read #3943

Balearica commented Oct 15, 2022

amitdo commented Oct 15, 2022

Balearica commented Oct 15, 2022

amitdo commented Oct 16, 2022 •

edited

Balearica commented Oct 19, 2022 •

edited

stweil commented Oct 19, 2022

stweil commented Oct 19, 2022 •

edited

Balearica commented Oct 19, 2022

amitdo commented Oct 19, 2022

stweil commented Oct 19, 2022

amitdo commented Oct 19, 2022 •

edited

Balearica commented Oct 20, 2022

Balearica commented Nov 4, 2022

Balearica commented May 10, 2023

PrintVariables produces config file that ReadConfigFile does not properly read #3943

PrintVariables produces config file that ReadConfigFile does not properly read #3943

Comments

Balearica commented Oct 15, 2022

Expected Behavior:

Current Behavior:

Suggested Fix:

Environment

amitdo commented Oct 15, 2022

Balearica commented Oct 15, 2022

amitdo commented Oct 16, 2022 • edited

Balearica commented Oct 19, 2022 • edited

stweil commented Oct 19, 2022

stweil commented Oct 19, 2022 • edited

Balearica commented Oct 19, 2022

amitdo commented Oct 19, 2022

stweil commented Oct 19, 2022

amitdo commented Oct 19, 2022 • edited

Balearica commented Oct 20, 2022

Balearica commented Nov 4, 2022

Balearica commented May 10, 2023

amitdo commented Oct 16, 2022 •

edited

Balearica commented Oct 19, 2022 •

edited

stweil commented Oct 19, 2022 •

edited

amitdo commented Oct 19, 2022 •

edited