get_bar_code_result — Get the alphanumerical results that were accumulated during the
decoding of bar code symbols.
get_bar_code_result( : : BarCodeHandle, CandidateHandle, ResultName : BarCodeResults)
The operator get_bar_code_result returns in BarCodeResults
alphanumeric results of the reading process.
In order to obtain a result, the bar code model (BarCodeHandle)
and the index of the resulting symbol or candidate
(CandidateHandle) are needed.
CandidateHandle refers to the read candidates in the order as
returned by the operator find_bar_code.
This implies, the possible values for CandidateHandle depend on the
queried result. Referring to decoded symbols, values from 0 to (n-1) are
possible (with n as the total number of successfully decoded symbols).
Referring to candidates, values from 0 to (m-1) are possible (with m as the
total number of candidates).
In cases the asked result is single valued,
CandidateHandle can also be set to 'all'
to return the results of all symbols or candidates.
With ResultName you can select, which kind of result is returned
in BarCodeResults.
The following values are supported:
returns the decoded result as a string in a human-readable format.
This decoded string can be returned for a single result, e.g.,
for CandidateHandle 0, or for all results simultaneously
when CandidateHandle is set to 'all'.
Note that only data characters are contained in the decoded string.
Start, stop, and check characters are excluded. For optional
check characters the behavior depends on the value of the
'check_char' parameter.
returns the bar code type of the decoded result as a string. This is
especially important in the context of autodiscrimination (see
find_bar_code). CandidateHandle specifies the
results for which the type should be returned:
The code type can be returned for a single result, e.g.,
for CandidateHandle 0 when requesting the type of
the first result, or for all results simultaneously if
CandidateHandle is set to 'all'.
returns the decoded result as a tuple of byte values. In contrast to 'decoded_reference', this contains the same high level processed data that is also returned for 'decoded_strings'. However, if the data contains binary non-printable characters, this parameter is more convenient. Also, for Code 128 or Code 93, the decoded data may contain NULL characters. In this case, the data can only be fully retrieved using this parameter, as the NULL character will otherwise terminate the string.
returns the underlying decoded reference data. It comprises all original characters of the symbol, i.e., data characters, potential start or stop characters and check characters if present. The specific result depends on the code type:
For codes taking only numeric data, like, e.g., the EAN/UPC codes, the GS1 DataBar codes (except the GS1 DataBar Expanded variants), or the 2/5 codes, the decoded reference data takes the same values as the decoded string data including check characters.
For codes with alphanumeric data, like for example Code 128 or Code 39 the decoded reference data are the indices of the respective decoding table.
For GS1-128, the decoded reference data are the indices of the respective decoding table. The special character FNC1 appears with value 102.
For GS1 DataBar Expanded and GS1 DataBar Expanded Stacked, the reference values are the ASCII codes of the decoded data (see also Tuple / String Operations), where the special character FNC1 appears with value 29.
Furthermore, for all codes from the GS1 DataBar family the first reference value represents a linkage flag with value of 1 if the flag is set and 0 otherwise.
As the decoded reference is a tuple of whole numbers
it can only be called for a single result, meaning that
CandidateHandle has to be the handle number of the
corresponding decoded symbol.
returns the decoded string of a GS1 Composite component. For further
details see the description of the parameter 'composite_code'
of set_bar_code_param.
returns the decoded string of a GS1 Composite component as a tuple of byte values. If the data contains binary non-printable characters, this parameter is more convenient than 'composite_strings'.
returns the orientation for the specified result. The
'orientation' of a bar code is defined as the angle between
its reading direction and the horizontal image axis. The angle is
positive in counter clockwise direction and is given in degrees.
It can be in the range of [-180.0 ...
180.0] degrees.
Note that the reading direction is perpendicular to the bars of the bar
code. In cases where the orientation of the bars can not be determined
reliably, e.g., for distorted codes, the orientation of the scanlines is
returned. A single angle is returned when only one result is specified,
e.g., by entering 0 for CandidateHandle. Otherwise,
when CandidateHandle is set to 'all', a tuple
containing the angles of all results is returned.
returns the size of bar code elements for the specified result.
returns a value indicating whether find_bar_code was aborted or
not:
find_bar_code completed.
find_bar_code was aborted by a timeout,
see set_bar_code_param.
find_bar_code was aborted using
set_bar_code_param with 'abort'.
returns a tuple with the assessment of print quality in compliance
with the international standard ISO/IEC 15416:2016.
Note that the print quality of a bar code can only be evaluated
if the bar code was decoded by find_bar_code in
'persistence' mode (see set_bar_code_param for
further details).
The first tuple element always contains the overall print quality of the
symbol. The length of the tuple and the interpretation of the remaining
elements depend on whether a simple 1D bar code is evaluated
(e.g., EAN-13, Code 128, GS1 DataBar) or a composite bar code
(e.g., GS1 DataBar Omnidirectional CC-A, GS1 DataBar Limited CC-B).
The names of the grades can be queried by setting ResultName
to 'quality_isoiec15416_labels', see below.
For the print quality assessment a set of scan reflectance profiles (scan lines) is generated across the symbol. For each scan line a grade for each of the evaluated parameters is allocated.
For compatibility reasons these grades are numbers from 0 to 4,
where 0 is the worst and 4 the best possible grade.
Setting ResultName to
'quality_isoiec15416_float_grades', the grades are returned
in accordance with the standard with one decimal place.
The worst of all parameter grades of a scan line is defined
as the scan reflectance profile grade. Thus, each scan line has an own
grade representing the respective minimal grade of all parameter grades
of this scan line. The arithmetic mean of all those scan line grades is
then returned as the overall symbol grade.
It is important to note that, even though the implementation is strictly based on the standard, the computation of the print quality grades depends on the decoding algorithm used. Thus, different bar code readers (of different vendors) can potentially produce slightly different results in the print quality assessment.
The tuple describing the print quality depends on whether the bar code is simple or composite:
The valuation of the print quality is described in a tuple with the following nine elements:
The arithmetic mean of the scan reflectance profile grade of each scan line. Note, that this value is, in most cases, not the minimum of the other symbol grades, because it depends on the individual scan reflectance profile grades.
Set to 4 when the reflectance profile of the symbol could be decoded according to the reference decode algorithm for the symbology and 0, otherwise. Note that HALCON's decode algorithm differs from the reference decode algorithm. Thus, in many cases HALCON can decode the symbol although the decode grade according to the standard is 0.
The range between the minimal and the maximal value in the reflectance profile. A strong contrast results in a good grading.
Set to 4 if the lowest reflectance value in the scan reflectance profile is lower or equal to 0.5 of the maximal reflectance value. Otherwise a value of 0 is assigned.
The contrast between any two adjacent elements, both bar-to-space or space-to-bar. The minimal edge contrast grades the minimum of the edge contrast values measured in the reflectance profile.
Indicates how strong the amplitudes of the bar code elements are. Big amplitudes make the assignment of the elements to bars or spaces more certain, resulting in a high modulation grade.
Reflects irregularities in the gray value profile found within elements and quiet zones.
Reflects deviations of the element widths from the nominal widths defined for the corresponding symbology.
A grade concerning symbology specific requirements of the bar code. It mostly regards the required quiet zones, but sometimes it can also be related to e.g., wide/narrow ratio, inter-character gaps, guarding patterns. For the following code types the conformity to the corresponding ISO/IEC standard cannot be guaranteed. This is mainly because the computation of the additional requirements requires the availability of metrical information.
the grade of the inter-character gap depends on the measured
narrow element width given in millimeters.
Since in find_bar_code neither metric information is
available nor can be calculated, get_bar_code_result will
only return the grade for the inter-character gap assuming that
the measured narrow element width is less than 0.287mm.
ISO/IEC 15420:2009 specifies the magnification factors as an additional criterion. A computation of this criterion is not possible since this would require knowledge of the metrical size of the bar code.
While overall quality is the final symbol grade to be reported, the rest of the grades give information for possible causes for poor quality of a symbol. A detailed list of frequently appearing defects and their effect on the individual grades can be found with the ISO/IEC 15416:2016 standard.
The valuation of the print quality is described in a tuple with 24
elements, which we organize for better clarity in three groups:
OVERALL, LINEAR, and COMPOSITE,
the latter one including a sub group.
The overall grades that are listed in the group OVERALL.
The grades in the groups LINEAR and COMPOSITE give
information of possible causes for poor quality of the symbol.
In the following, the individual tuple elements with their corresponding index and definition are listed in groups.
The group OVERALL:
These grades represent the respective minimum of all individual
grades of each group.
The final symbol grade to be reported. It returns the minimum of all grades.
The overall grade for the symbols of the group
LINEAR, the linear 1D symbols. This grade returns the
minimum of all grades belonging to the group.
The overall grade for the symbols of the group
COMPOSITE, the composite 2D symbols. This grade returns
the minimum of all grades belonging to the group.
The group LINEAR:
The interpretation of the grades in the LINEAR group
correspond to those for simple 1D bar codes described above.
The group COMPOSITE:
these grades are equivalent to the quality grades for PDF 417 data
code symbols, thus of two-dimensional symbols according to
ICO/IEC 15415:2011 (see 'quality_isoiec15415' in
get_data_code_2d_results).
However, there is a difference:
For PDF 417 data code symbols a start/stop pattern is used for the
evaluation concerning the quality of the reflectance profile.
In contrast, for composite bar codes so-called Raw Address
Patterns (RAP) are used instead of a start/stop pattern.
The grades of the respective RAP symbols are organized in the
sub group COMPOSITE RAP and are consistent with the grades
for simple 1D bar codes.
Grade for the decodability of the composite symbol part. Its meaning and determination is equivalent to the one for simple 1D bar codes described above.
Minimum of all individual grades of the sub group
COMPOSITE RAP.
Grade of the COMPOSITE RAP sub group, corresponds to the
one for simple 1D bar codes as described above.
Grade of the COMPOSITE RAP sub group, corresponds to the
one for simple 1D bar codes as described above.
Grade of the COMPOSITE RAP sub group, corresponds to the
one for simple 1D bar codes as described above.
Grade of the COMPOSITE RAP sub group, corresponds to the
one for simple 1D bar codes as described above.
Grade of the COMPOSITE RAP sub group, corresponds to the
one for simple 1D bar codes as described above.
Grade of the COMPOSITE RAP sub group, corresponds to the
one for simple 1D bar codes as described above.
Counts and evaluates the relative number of correct decoded words acquired by the set of scan profiles.
Counts and evaluates the relative number of false decoded words within the error correction blocks.
Grades the ratio of the minimum edge contrast to the symbol contrast. indicates how strong the amplitudes, i.e., the extremal intensities, of the bars and spaces are.
Grades the uniformity of reflectance of the dark and light modules, respectively.
Refers to a measurement of how perfect the reflectance profiles of bars and spaces are.
returns a tuple with the same assessment of print quality like
'quality_isoiec15416'.
In compliance with the international standard ISO/IEC 15416:2016 the
grades are returned with one decimal place.
The names of the grades can be queried by setting ResultName
to 'quality_isoiec15416_labels', see below.
Note that the print quality of a bar code can only be evaluated
if the bar code was decoded by find_bar_code in
'persistence' mode (see set_bar_code_param for
further details).
returns a tuple with the raw values for all 'directly
measurable' grades (returned with ResultName to
'quality_isoiec15416').
These are the grades, whose definition in the ISO/IEC 15416:2016
standard is a 'direct derivative' of the reflectance
(i.e., the gray values) properties of the symbol or grades that are
the result of a 'direct counting'.
Additionally the three overall grades overall quality,
overall linear, and overall composite are returned
(see their explanation above in 'quality_isoiec15416').
Note that the print quality of a bar code can only be evaluated
if the bar code was decoded by find_bar_code in
'persistence' mode (see set_bar_code_param for
further details).
The names of the tuple elements can be queried by setting
ResultName to 'quality_isoiec15416_labels', see below.
All values (not grades) are normalized between 0.0 and 1.0. Hence, for example, a symbol contrast value of 0.75 will correspond to a gray value of 191.25 (for byte images).
Which values make up the tuple depends on whether the bar code is a simple 1D or a composite bar code:
The following values are returned by the respective index:
The following values are returned by the respective index:
These tuples have the same length as the tuple with the grades
returned when setting ResultName to
'quality_isoiec15416' and
'quality_isoiec15416_float_grades', respectively.
For the entries not listed above, the operator reports 'N/A'.
In case of simple 1D bar codes, the grades decode and
additional requirements do not have any interpretation in the
reflectance profile and as a consequence the value 'N/A'
is returned.
For composite bar codes this is the case for the grades
decode (LINEAR),
additional requirements (LINEAR),
decode (COMPOSITE), and
RAP overall (COMPOSITE).
Note that although the grades modulation
(COMPOSITE), decodability (COMPOSITE),
and defects (COMPOSITE) are grading the gray value
reflectance profile of a composite symbol,
'N/A' is reported for them as well.
This is because they are computed in a complicated scheme involving
the symbology decoding routine and the error correction mechanism.
As a consequence they do not have a direct raw measurement
interpretation.
returns convenience grade labels of the elements of the tuple returned
when calling get_bar_code_result with
'quality_isoiec15416'. Note, that in order to be able to
discriminate the composite from the linear grading case, the operator
needs a handle of a valid result to be passed in
CandidateHandle.
determines and returns additional information about scanlines of a
given candidate region in a human-readable format.
Here, CandidateHandle can take numbers from 0 to
(m-1), where m is the total number of candidates.
Note in order to evaluate the status of the bar code scanlines
the preceding call of the operator find_bar_code or
decode_bar_code_rectangle2 needs to be done in the mode
'persistence', see set_bar_code_param.
For the calculation of additional information the given candidate region
is scanned again.
In doing so, the bar code reader exits only after evaluation of all
scanlines and not usual after a successful decoding.
This is computationally expensive and should be queried only if additional
information is needed.
For further information on setting scanline parameters, see
set_bar_code_param.
The operator returns for every scanline of the candidate region
a status message and possible warning message, which will be added to the
string containing the status message.
These messages are sorted in the same order as the scanlines themselves
are returned by get_bar_code_object with the parameter
'scanlines_all'.
The possible messages of these categories are listed below.
Status messages:
The following list shows the possible messages grouped into stages in which the message can appear. The numbers are the corresponding status codes returned by 'status_id' (see below).
The status of this scanline is unknown. The scanline will be ignored.
The scanline could be decoded successfully.
The number of edges in this scanline is too low for this bar code type.
The number of edges in this scanline is too low to find at least the start pattern, the stop pattern and a data character.
The number of edges in this scanline is too high for this bar code type.
The symbology specific stop character could not be found.
The symbology specific start and stop characters could not be found.
Internal error.
Internal error.
For bar code types '2/5 Industrial' and '2/5 Interleaved', the number of wide bars in a single character must be two.
The encoding pattern does not correspond to a character in the symbology specific decoding table.
For bar code types 'EAN-13' and 'UPC-A', the left half of the symbol contains an invalid mix of the number sets A and B.
For example, this could happen if not enough characters (depending on whether a check character is expected) could be found.
For bar code types 'EAN-13', 'EAN-8', and 'UPC-A' (including add-on variants) the obligatory center guard pattern could not be found.
For bar code types 'EAN-13', 'EAN-8', and 'UPC-A' (including add-on variants) either the obligatory left or right normal guard patterns could not be found. For bar code types 'UPC-E' (including add-on variants) either the left normal or right special guard patterns could not be found.
For bar code types 'EAN-13', 'EAN-8', 'UPC-A', and 'UPC-E' containing add-on symbols, the obligatory add-on guard pattern could not be found.
For bar code types of the GS1 DataBar family, not enough finder patterns could be found.
For stacked bar code types no segment could be found.
The check character test failed. For bar codes with an optional
check character, it is possible to disable the check character
testing with 'check_char' in set_bar_code_param.
For bar code types 'EAN-13', 'EAN-8', 'UPC-A', and 'UPC-E' containing add-on symbols, the mix of the number sets A and B does not match the implicit check digit.
For the bar code type 'UPC-A' and its add-on variants, the left half of the symbol must consist of six symbol characters of number set A, but a 'EAN-13' compatible mix of number sets A and B has been found instead. Try decoding the bar code as 'EAN-13'.
The bar code could be decoded, but its symbol region intersects with the symbol region of another successfully decoded symbol.
While scanning a candidate region in autodiscrimination mode
(see find_bar_code with CodeType='auto'),
the decoder was unable to detect which bar code type the symbol
belongs to.
The quiet zone check was not successful. See the section
'quiet_zone' in set_bar_code_param for further
information.
A bar code could be decoded, but the resulting symbol region does not intersect the original candidate region. This is an indication that random clutter or another candidate was detected by accident by the scanlines used to scan the original candidate.
The number of characters in the found code is smaller than the
required amount.
See the section 'min_code_length' in
set_bar_code_param for further information about the
minimal required code length.
Warning messages:
The messages listed below are only warnings, not errors. They can appear in combination with a status message and are then added to the status message string. These messages are returned if the bar code reader detects possible quality issues in the input image. The messages 1000 to 1003 can appear only for successfully decoded scanlines and only for the following bar code types: 'Codabar', '2/5 Industrial', '2/5 Interleaved', 'Code 39', 'Code 93', 'GS1-128', 'Code 128', 'MSI', all 'EAN'-, 'UPC-A'- and 'UPC-E'-variants. Note that in cases where scanlines were already decoded incorrectly but not recognized as invalid by the bar code reader, these warnings will be wrong and must be ignored.
The measured width of the white spaces is bigger than internally expected. This is not a decoding error, but a warning that increasing white spaces could lead to undecodable symbols.
The measured width of the white spaces is smaller than internally expected. This is not a decoding error, but a warning that decreasing white spaces could lead to undecodable symbols.
The measured width of the bars is bigger than internally expected. This is not a decoding error, but a warning that increasing the width of the bars could lead to undecodable symbols.
The measured width of the bars is smaller than internally expected. This is not a decoding error, but a warning that decreasing the width of the bars could lead to undecodable symbols.
Internal algorithms show that the white pixels in the symbol region could be saturated. This warning is not bar code type specific. This warning is returned for each scanline. For example, the combination of the status messages 1001/1004 or 1003/1004 is a hint, that the input images might be overexposed.
The linkage flag in the linear bar code component indicates that there should be a composite component, but the composite component could not be found. The decoder returned the linear component only. This warning is returned for each scanline.
This message is an information that some edges of the current scanline were used to compute the merged scanline.
returns additional information about scanlines in a numeric format that
can be easily parsed.
The description of this functionality and the message numbers are
described with the parameter 'status' above.
The numbers of the warnings can be returned together with
other status numbers. The single status message and warning numbers for
each scanline are returned as a
string, separated by a semicolon, e.g. '1;1000;1004'.
determines the status of an optional decoding attempt, which is described
in the section about 'small_elements_robustness' in
set_bar_code_param. Additionally to the messages listed for
'status', 'status_small_elements_robustness' can return
the status 'small_elements_robustness: no scan.' if for some
reason the algorithm was not executed or failed.
BarCodeHandle (input_control) barcode → (handle)
Handle of the bar code model.
CandidateHandle (input_control) integer → (string / integer)
Indicating the bar code results respectively candidates for which the data is required.
Default value: 'all'
Suggested values: 0, 1, 2, 'all'
ResultName (input_control) attribute.name → (string)
Names of the resulting data to return.
Default value: 'decoded_types'
Suggested values: 'decoded_types', 'decoded_strings', 'decoded_data', 'decoded_reference', 'element_size', 'orientation', 'composite_strings', 'composite_reference', 'aborted', 'quality_isoiec15416', 'quality_isoiec15416_labels', 'quality_isoiec15416_values', 'quality_isoiec15416_float_grades', 'status', 'status_id', 'status_small_elements_robustness'
BarCodeResults (output_control) attribute.value(-array) → (string / integer / real)
List with the results.
The operator get_bar_code_result returns the value 2 (H_MSG_TRUE)
if the given parameters are correct and the requested results are
available for the last symbol search.
Otherwise, an exception will be raised.
Bar Code