préface
OIN (Organisation internationale de normalisation) est une alliance mondiale d'organismes de normalisation nationaux (Comités membres de l'ISO). L'élaboration de normes internationales est généralement réalisée par l'intermédiaire de comités techniques ISO.. Chaque institution membre intéressée par un sujet pour lequel un comité technique a été créé a le droit d'être représentée au sein de ce comité.. Les organisations internationales gouvernementales et non gouvernementales en liaison avec l'ISO sont également impliquées dans ces travaux.. L'ISO travaille en étroite collaboration avec la Commission électrotechnique internationale (CEI) sur toutes les questions de normalisation électrotechnique.

Les normes internationales sont rédigées conformément aux règles données dans la partie 2 de la directive ISO/CEI.

La tâche principale du comité technique est d'établir des normes internationales. Les projets de normes internationales adoptés par le Comité technique seront distribués aux comités membres pour vote.. La publication en tant que norme internationale nécessite l'approbation d'au moins 75% des comités membres.

Veuillez noter que certains contenus de ce document peuvent être soumis à des droits de brevet.. L'ISO n'est pas responsable de l'identification de tout ou partie de ces brevets..

OIN 21227-1 a été développé par le comité technique ISO/TC 35, Peintures et vernis, Sous-comité SC 9, Méthodes d'essai courantes pour les peintures et vernis.

OIN 21227-1-2003 Peintures et vernis, Évaluation des défauts sur les surfaces revêtues par imagerie optique – Partie 1: Conseils généraux

OIN 21227 consists of the following parts under the general heading Paints and Varnishes – Assessment of Defects on coated Surfaces Using optical Imaging:

— Partie 1: Conseils généraux

— Partie 2: Evaluation procedure for multiple impact lithotriptic test results

— Partie 3: Assessment procedures for delamination and corrosion around lines

At the time this part of ISO 21227 was published, Parts 2 et 3 were being prepared.

introduire
Traditional ISO testing methods used to assess surface defects and appearance changes typically use graphic standards that depict specific types of surface deterioration and require human visual evaluation. Compared with human visual assessment techniques, the techniques described in the various sections of this standard can produce more objective, précis, quantitative and repeatable results.

OIN 21227-1-2003 Peintures et vernis, Évaluation des défauts sur les surfaces revêtues par imagerie optique – Partie 1: Conseils généraux

1 gamme
Cette partie de l'ISO 21227 defines and provides guidance for the use of optical imaging systems to quantitatively characterize defects that occur on the surface of coatings after exposure in various test methods (par exemple. lithotripsy, weathering or crosscutting tests). One goal of ISO 21227 is to use optical imaging to reproduce the results of existing visual evaluation methods. En outre, optical imaging provides more information that can be used to assess coating defects in more detail.

Cette partie de l'ISO 21227 contains a general introduction to optical imaging methods and definitions. The performance and accuracy requirements of individual test methods are described in other sections of the standard.

2 Références normatives
The following references are required for the use of this document. Pour les références datées, les versions avec citation uniquement s'appliquent. Pour les références non datées, la nouvelle version de la référence (y compris toutes les révisions) s'applique.

CIE publication No. 17.4:1987, International Vocabulary for Lighting /IEC 60050-845:1987, International Vocabulary for Electricians – Éclairage

3 Termes et définitions
Aux fins de ce document, les termes et définitions suivants s'appliquent.

3.1 Optical Imaging

A method of acquiring, digitizing, processing, and analyzing images using optical elements and computer systems

3.2 Éclairage

Apply light to a scene, object, or its surroundings so that they can be seen

[Source: CIE 17.4:1987 /CEI 60050-845:1987]

3.2.1 Reflection Lighting

Light source and optical sensor are arranged on the same side of the object lighting

3.2.2 Transmission Lighting

Light sources and optical sensors arranged on opposite sides of an object for illumination

3.2.3 Open field lighting

An image acquisition method for detecting light reflected by an object and light scattered by an object by an optical sensor

3.2.4 Dark field lighting

An image acquisition method in which an optical sensor detects only the light scattered by an object

3.2.5 Directional Lighting

Illumination in which light on a working plane or object is primarily incident from a particular direction

[Source: CIE 17.4:1987 /CEI 60050-845:1987]

3.2.6 Diffuse Lighting

Light on a working surface or object does not come primarily from illumination in a particular direction

[Source: CIE 17.4:1987 /CEI 60050-845:1987]

3.3 Terms related to optical sensors

3.3.1 Visual Field

The area on the surface of an object picked up by an optical sensor

3.3.2 Region of Interest

The part of the original image used for image processing and image analysis

3.3.3 But

An optical system, usually consisting of one or more lenses, used to acquire a visual field image

OIN 21227-1-2003 Peintures et vernis, Évaluation des défauts sur les surfaces revêtues par imagerie optique – Partie 1: Conseils généraux

3.3.4 Object distance

The distance between the first lens of the objective lens and the object provides a clear image

3.3.5 Focal depth

The difference between minimum and maximum object distances

3.4 Image Acquisition

Image capture

The process of creating a two-dimensional raw image of an object

3.4.1 Original image

The digital image taken by the image acquisition system does not require any image processing

3.4.2 Charge-coupled device CCD

A device that uses semiconductor materials as optical sensors

Note 1: CCD chips are subdivided into very fine components, each corresponding to a pixel of the digitized image. CCDS can be arranged in arrays (digital cameras) or rows (line scanners).

3.4.3 Scanner

An image acquisition device using a one-dimensional optical sensor in which CCDS are arranged in a row

Note 1: The image is built by line scanning the surface of the object.

3.4.4 Digitization

The process of converting an analog image to a digital image

Note 1: The image is divided into pixels by a grid, and each pixel is assigned a grayscale level.

3.4.5 pixels

The minimum image forming element to which grayscale is assigned

3.4.6 Résolution

The number of pixels per unit length on an object surface

Note 1: If the resolution in the X and Y directions is different, the two values need to be reported.

3.4.7 Gray level

The shade of gray assigned to the pixel

Note 1: The shadow is usually a positive integer value taken from the gray level.

3.4.8 Gray scale

A series of grays between white and black

Exemple: The 8-bit gray scale has 28 (= 256) grays. Grey level 0 corresponds to black and grey level 255 (256th) corresponds to white.

3.4.9 Gamma C

The function Y is equal to X, the exponent gamma

X is the input signal;
Y is the output signal;
X and Y range from 0 à 1 (0 for black, 1 for white)
3.4.10 Image Acquisition Card

A device used to convert an analog video signal into a digital raw image

3.5 Image Processing

The software manipulates the original image to prepare it for subsequent image analysis

Note 1: Par exemple, image processing may be used to eliminate errors generated during image acquisition or to reduce image information to the desired extent.

3.5.1 Binary Image

An image in which each pixel is 0 (black) ou 1 (white)

3.5.2 Gamma correction

The modification of gamma value can be carried out by software or hardware

3.5.3 Brightness

The average gray of a specified portion of the image

3.5.4 Contrast

The difference between the grayscale of two specified parts of an image

OIN 21227-1-2003 Peintures et vernis, Évaluation des défauts sur les surfaces revêtues par imagerie optique – Partie 1: Conseils généraux

3.5.5 Shadow correction

Software method for correcting object illumination inhomogeneity

3.5.6 Thresholding

To reduce the number of different gray levels of the image, it is recommended to obtain a binary image

Note 1: To generate a binary image, each pixel in a grayscale image is assigned a grayscale level of 0 ou 1, depending on whether the pixel’s grayscale is greater than, less than, or equal to a given constant (the threshold).

3.5.7 Partition

Edge detection

A method for isolating and locating optical edges in a given digital image

3.6 Image Analysis

Reduces image information to a set of application-specific values

3.6.1 Reference Panel

A specified panel that has been evaluated and therefore has a known rating

Note 1: It is used to check the reproducibility and repeatability of parameter Settings.

3.7 Image Evaluation

The process of associating a set of values resulting from image analysis with one or more characteristic values through a classification or rating scheme