ISO/IEC 29158:2020

INTERNATIONAL ISO/IEC
STANDARD 29158
First edition
2020-12
Information technology — Automatic
identification and data capture
techniques — Direct Part Mark (DPM)
Quality Guideline
Technologies de l'information — Techniques automatiques
d'identification et de capture de données — Ligne directrice de
qualité du marquage direct sur pièce (DPM)
Reference number
©
ISO/IEC 2020
© ISO/IEC 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii © ISO/IEC 2020 – All rights reserved

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 2
5 Overview of methodology . 2
5.1 Process differences from ISO/IEC 15415. 2
5.2 Lighting . 3
5.3 Tilted coaxial lighting and camera position (TCL) . 3
6 Obtaining the image . 4
6.1 Camera position and symbol orientation. 4
6.1.1 Symbol placement . 4
6.1.2 Camera position in a 90 ° camera angle set up . 5
6.1.3 TCL setup . 5
6.2 Lighting environments . 5
6.2.1 General. 5
6.2.2 Perpendicular coaxial (90) . 5
6.2.3 Diffuse off-axis (D) . 5
6.2.4 Four direction (angle Q) . 5
6.2.5 Two direction (angle T) . 5
6.2.6 One direction (angle S) . 6
6.2.7 TCL Setup . 6
6.3 Image focus . 6
6.4 Depth of field . 6
6.5 System response adjustment and reflectance calibration . 6
7 Verifying a symbol . 7
7.1 Initial image reflectance. 7
7.1.1 General. 7
7.1.2 Initialize aperture size . 7
7.1.3 Create initial histogram. 7
7.1.4 Compute mean . 7
7.1.5 Optimize image . 7
7.2 Obtaining the test image . 7
7.2.1 Matrix symbologies . 7
7.2.2 Binarize image . 7
7.3 Apply Reference Decode Algorithm . 8
7.3.1 General. 8
7.3.2 Repeat if necessary . 8
7.3.3 Continue until end . 8
7.4 Final image adjustment . 8
7.4.1 General. 8
7.4.2 Determine grid-point reflectance with two apertures . 8
7.4.3 Create a grid-point histogram . 8
7.4.4 Measure mean light (M ) . 8
L
7.4.5 Record parameters . . 8
7.4.6 Create binarized images for the symbology reference decode . 9
7.4.7 Decode . 9
8 Determine contrast parameters . 9
8.1 Initialize aperture size . 9
8.2 Calculate cell contrast (CC) . 9
© ISO/IEC 2020 – All rights reserved iii

8.3 Calculate cell module modulation (CMOD) . 9
8.4 Calculate minimum reflectance (R ) . 9
target
9 Grading .10
9.1 Cell contrast (CC) .10
9.2 Minimum reflectance (R ) .10
target
9.3 Cell modulation (CM) .11
9.4 Fixed pattern damage (FPD) .11
9.5 Final grade .12
10 Communicating grade requirements and results .12
10.1 General .12
10.2 Communication of application requirements .12
10.3 Communicating from verifier to application .12
10.4 Communicating the use of a proprietary decode .12
Annex A (normative) Threshold determination method .14
Annex B (informative) Evaluation of image at virtual 90° camera position from real tilted
camera position .18
Annex C (normative) Continuous grading for ISO/IEC 15415 parameters .22
Annex D (normative) Dot connecting algorithm .27
Annex E (informative) Communicating the grade .29
Annex F (informative) Cross reference to ISO/IEC 15415 .32
Bibliography .33
iv © ISO/IEC 2020 – All rights reserved

Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National
...