ISO/IEC 30116:2016

Information technology — Automatic identification and data capture techniques — Optical Character Recognition (OCR) quality testing

ISO/IEC 30116:2016 - specifies the methodology for the measurement of specific attributes of OCR-B character strings, - defines a method for evaluating these measurements and deriving an overall assessment of character string quality, - defines a reference decode algorithm for OCR-B, and - gives information on possible causes of deviation from optimum grades to assist users in taking appropriate corrective action. ISO/IEC 30116:2016 applies to OCR-B as defined in ISO 1073‑2, but its methodology can be applied partially or wholly to other OCR fonts.

Technologies de l'information — Techniques automatiques d'identification et de capture des données — Essais de qualité des caractères pour reconnaissance optique

General Information

• Status: Published
• Publication Date: 04-Oct-2016
• ICS: 35.040 - Information coding
• ICS: 35.040.50 - Automatic identification and data capture techniques
• Technical Committee: ISO/IEC JTC 1/SC 31 - Automatic identification and data capture techniques
• Drafting Committee: ISO/IEC JTC 1/SC 31/WG 1 - Data carrier
• Current Stage: 9093 - International Standard confirmed
• Start Date: 11-Apr-2022
• Completion Date: 11-Apr-2022

Standards Content (Sample)

DRAFT INTERNATIONAL STANDARD
ISO/IEC DIS 30116
ISO/IEC JTC 1/SC 31 Secretariat: ANSI
Voting begins on: Voting terminates on:
2015-09-30 2015-12-30
Information technology — Automatic identification and
data capture techniques — Optical Character Recognition
(OCR) quality testing
Titre manque
ICS: 35.040
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/IEC DIS 30116:2015(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO/IEC 2015

ISO/IEC DIS 30116:2015(E)
© ISO/IEC 2015, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO/IEC 2015 – All rights reserved

ISO/IEC WD 30116
Contents Page
Foreword .v
Introduction .vi
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
3.1 binarized image .1
3.2 document reference edge .1
3.3 inspection area .2
3.4 COL .2
3.5 pixel.2
3.6 raw image .2
3.7 reference grey-scale image .2
3.8 scan grade .2
3.9 stroke width .2
3.10 SWT .2
3.11 symbol .3
3.12 X-Tolerance.3
3.13 Y-Tolerance.3
4 Abbreviated terms .3
5 Quality grading .3
6 Measurement methodology for OCR-B .3
6.1 Overview of methodology .3
6.2 Obtaining the test image .3
6.2.1 Measurement conditions.3
6.2.2 Raw image .4
6.2.3 Reference grey-scale image.4
6.2.4 Binarized image .4
6.3 Reference reflectivity measurements .4
6.3.1 General requirements.4
6.3.2 Light sources .4
6.3.3 Effective resolution .4
6.3.4 Optical geometry .4
6.3.5 Inspection area .7
6.4 Basis of symbol grading .8
6.5 Capture the raw image .8
6.6 Image assessment parameters and grading .8
6.6.1 Determining the document horizontal axis .8
6.6.2 Character best-fit algorithm .8
6.6.3 Position of a character .10
6.6.4 Character Evaluation Value (CEV) in the best-fit location .10
6.6.5 Background noise .11
6.6.6 Contrast PCS of the characters .11
7 Reporting the Grade .11
Annex A OCR-B Character Centreline Coordinates (Normative) .13
Annex B Threshold Determination Method (Normative) .21
B.1 Algorithm description .21
B.2 Example .21
Annex C OCR Reference Decode Algorithm (Normative) .25
Annex D Example calculation of Character Evaluation Value (CEV)

© ISO/IEC 2011 – All rights reserved iii

ISO/IEC WD 30116
Bibliography
iv © ISO/IEC 2011 – All rights reserved

ISO/IEC WD 30116
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International
Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO/IEC 30116 was prepared by Technical Committee ISO/TC , , Subcommittee SC 31, Automatic identification
and data capture techniques.
This second/third/. edition cancels and replaces the first/second/. edition (), [clause(s) / subclause(s) / table(s)
/ figure(s) / annex(es)] of which [has / have] been technically revised.
© ISO/IEC 2011 – All rights reserved v

ISO/IEC WD 30116
Introduction
For the inspection of ID documents, i.e. MRTDs (Machine Readable Travel Documents) according to ISO/IEC
7501 and driving licences according to ISO/IEC 18013, a reliable and ergonomic document inspection
technology is essential. Considering RFID interoperability, strong improvement has been reached introducing
mechanisms for interoperability evaluation and testing of MRTDs and reader devices. Similar standards for
optical reading would improve the reliability of OCR. This is especially important because OCR of the
document’s MRZ (Machine Readable Zone) is essential for accessing BAC (Basic Access Control) and/or SAC
(Supplementary Access Control) protected passports.
Thus, reliable OCR makes the performance of Automated Border Control systems as well as of many other
applications more predictable. Furthermore, the evaluation of document reader products can be done much
easier. This standardization project defines test methods to evaluate OCR document quality. Furthermore, it
defines requirements ensuring the compliance to the applicable OCR standards. The project applies
experiences from other domains such as bar code reading and possibly other test methods for OCR. Where
conflicts in the specification work between MRTDs and driving licenses may arise, satisfying the definitions for
MRTDs shall be given preference.
vi © ISO/IEC 2011 – All rights reserved

DIS ISO/IEC WD 30116
Information technology — Automatic identification and data
capture techniques — Optical Character Recognition (OCR)
quality testing
1 Scope
This International Standard
-specifies the methodology for the measurement of specific attributes of OCR-B character strings;
-defines a method for evaluating these measurements and deriving an overall assessment of character string
quality;
-defines a reference decode algorithm for OCR-B;
-gives information on possible causes of deviation from optimum grades to assist users in taking appropriate
corrective action.
This International Standard applies to OCR-B as defined in ISO 1073-2, but its methodology can be applied
partially or wholly to other OCR fonts.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced document
(including any amendments) applies.
ISO/IEC 19762 Information technology -- Automatic identification and data capture (AIDC) techniques --
Harmonized vocabulary
3 Terms and definitions
3.1
binarized image
binary (black/white) image created by applying the Global Threshold to the pixel values in the reference grey-
scale image
3.2
document reference edge
physical (i.e. mechanical) end of the surface with the MRZ whose position is determined by putting a black
background under the surface with the MRZ and sliding the document up against a physical stop
© ISO/IEC 2011 – All rights reserved 1

ISO/IEC WD 30116
3.3
inspection area
rectangular area which contains the entire symbol to be tested inclusive of its quiet zones
3.4
character outline limits
outlines of an ideal printed image of a character
Note: this is a qualitative evaluation utilized in ISO 1836 that is replaced in this standard with SWT
3.5
pixel
individual light-sensitive element in a light-sensitive array (e.g. CCD (charge coupled device) or CMOS
(complementary metal oxide semiconductor) device)
3.6
raw image
matrix of the reflectance values in x and y coordinates across a two-dimensional image, derived from the
discrete reflectance values of each pixel of the light-sensitive array
3.7
reference grey-scale image
raw image convolved with a synthesised circular aperture
3.8
scan grade
result of the assessment of a single scan of an OCR symbol, derived by taking the lowest grade achieved for
any measu
...

INTERNATIONAL ISO/IEC
STANDARD 30116
First edition
2016-10-01
Information technology — Automatic
identification and data capture
techniques — Optical Character
Recognition (OCR) quality testing
Technologies de l’information — Techniques automatiques
d’identification et de capture des données — Essais de qualité des
caractères pour reconnaissance optique
Reference number
©
ISO/IEC 2016
© ISO/IEC 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO/IEC 2016 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 3
5 Quality grading . 3
6 Measurement methodology for OCR-B . 3
6.1 Overview of methodology . 3
6.2 Obtaining the test image . 3
6.2.1 Measurement conditions . 3
6.2.2 Raw image . 3
6.2.3 Reference grey-scale image . 3
6.2.4 Binarized image . 4
6.3 Reference reflectivity measurements . 4
6.3.1 General requirements . 4
6.3.2 Light sources . 4
6.3.3 Effective resolution . 4
6.3.4 Optical geometry . 4
6.3.5 Inspection area . 8
6.4 Basis of symbol grading . 8
6.5 Capture the raw image . 9
6.6 Image assessment parameters and grading . 9
6.6.1 Determining the document horizontal axis . 9
6.6.2 Character best-fit algorithm . . 9
6.6.3 Position of a character .11
6.6.4 Character evaluation value (CEV) in the best-fit location .11
6.6.5 Background noise . .12
6.6.6 Contrast PCS of the characters .12
7 Reporting the grade .12
Annex A (normative) OCR-B character centreline coordinates .14
Annex B (normative) Threshold determination method .20
Annex C (normative) OCR reference decode algorithm .24
Annex D (informative) Example calculation of character evaluation value (CEV) .25
Bibliography .29
© ISO/IEC 2016 – All rights reserved iii

Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are
members of ISO or IEC participate in the development of International Standards through technical
committees established by the respective organization to deal with particular fields of technical
activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international
organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the
work. In the field of information technology, ISO and IEC have established a joint technical committee,
ISO/IEC JTC 1.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for
the different types of document should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject
of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent
rights. Details of any patent rights identified during the development of the document will be in the
Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment,
as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the
Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.
The committee responsible for this document is ISO/JTC 1, Information technology, Subcommittee SC 31,
Automatic identification and data capture techniques.
iv © ISO/IEC 2016 – All rights reserved

Introduction
For the inspection of ID documents, i.e. MRTDs (Machine Readable Travel Documents) according to
ISO/IEC 7501 (all parts)/ICAO Doc 9303 (all parts) and driving licences according to ISO/IEC 18013
(all parts), a reliable and ergonomic document inspection technology is essential. Considering RFID
interoperability, strong improvement has been reached introducing mechanisms for interoperability
evaluation and testing of MRTDs and reader devices. Similar standards for optical reading would
improve the reliability of OCR. This is especially important because OCR of the document’s MRZ (Machine
Readable Zone) is essential for accessing BAC (Basic Access Control) and/or SAC (Supplementary Access
Control) protected passports.
Thus, reliable OCR makes the performance of automated border control systems, as well as of many
other applications, more predictable. Furthermore, the evaluation of document reader products can be
done much easier. This standardization project defines test methods to evaluate OCR document quality.
Furthermore, it defines requirements ensuring the compliance to the applicable OCR standards. The
project applies experiences from other domains such as bar code reading and possibly other test
methods for OCR. Where conflicts in the specification work between MRTDs and driving licenses may
arise, satisfying the definitions for MRTDs is given preference.
© ISO/IEC 2016 – All rights reserved v

INTERNATIONAL STANDARD ISO/IEC 30116:2016(E)
Information technology — Automatic identification and
data capture techniques — Optical Character Recognition
(OCR) quality testing
1 Scope
This document
— specifies the methodology for the measurement of specific attributes of OCR-B character strings,
— defines a method for evaluating these measurements and deriving an overall assessment of character
string quality,
— defines a reference decode algorithm for OCR-B, and
— gives information on possible causes of deviation from optimum grades to assist users in taking
appropriate corrective action.
This document applies to OCR-B as defined in ISO 1073-2, but its methodology can be applied partially
or wholly to other OCR fonts.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1
binarized image
binary (black/white) image created by applying the global threshold to the pixel (3.5) values in the
reference grey-scale image
3.2
document reference edge
physical (i.e. mechanical) end of the surface with the MRZ whose position is determined by putting a
black background under the surface with the MRZ and sliding the document up against a physical stop
3.3
inspection area
rectangular area which contains the entire symbol (3.11) to be tested inclusive of its quiet zones
3.4
character outline limits
outlines of an ideal printed image of a character
Note 1 to entry: This is a qualitative evaluation utilized in ISO 1831 that is replaced in this document with SWT.
© ISO/IEC 2016 – All rights reserved 1

3.5
pixel
individual light-sensitive element in a light-sensitive array
Note 1 to entry: Examples of light-sensitive array are CCD (charge coupled device) or CMOS (complementary
metal oxide semiconductor) device.
3.6
raw image
matrix of the reflectance values in x and y coordinates across a two-dimensional image, derived from
the discrete reflectance values of each pixel (3.5) of the light-sensitive array
3.7
reference grey-scale image
raw image (3.6) convolved with a synthesized circular aperture
3.8
scan grade
result of the assessment of a single scan of an OCR symbol, derived by taking the lowest grade achieved
for any measured parameter of the reference grey-scale and binarized images (3.1)
3.9
stroke width
nominal dimension perpendicular to the direction of the line making up an OCR character
3.10
stroke width template
inner and outer character boundaries defined by circles whose centres follow the line created by the
character centreline coordinates defined in Annex A
3.11
symbol
group of OCR characters comprising the entire machine-readable entity (e.g. Machine Readable Zone
(MRZ) as specified in ICAO 9303, sizes ID-1, ID-2 and ID-3) including quiet zones and the document
reference edge (3.2)
Note 1 to entry: Document sizes are defined in ISO/IEC 7501 (all parts) (ICAO 9303) as TD1, TD2 and TD2,
whereas the same sizes are defined in ISO/IEC 7810 as ID-1, ID-1 and ID-3. In this document, we use the terms
I
...