prefácio
ISO (Organização Internacional para Padronização) é uma aliança global de organismos nacionais de normalização (Órgãos membros da ISO). O desenvolvimento de padrões internacionais é geralmente realizado através de comitês técnicos ISO. Cada instituição membro interessada em um assunto sobre o qual tenha sido estabelecido um comitê técnico tem o direito de ser representada nesse comitê. Organizações internacionais governamentais e não governamentais em ligação com a ISO também estão envolvidas neste trabalho. A ISO trabalha em estreita colaboração com a Comissão Eletrotécnica Internacional (CEI) em todos os assuntos de padronização eletrotécnica.

As normas internacionais são elaboradas de acordo com as regras fornecidas na Parte 2 da Diretiva ISO/IEC.

A principal tarefa do comitê técnico é estabelecer padrões internacionais. Os projetos de normas internacionais adotados pelo Comitê Técnico serão distribuídos aos órgãos membros para votação. A publicação como padrão internacional requer aprovação de pelo menos 75% dos órgãos membros.

Observe que determinados conteúdos deste documento podem estar sujeitos a direitos de patente. A ISO não é responsável por identificar nenhuma ou todas essas patentes.

ISO 21227-1 foi desenvolvido pelo Comitê Técnico ISO/TC 35, Tintas e Vernizes, Subcomitê SC 9, Métodos de teste comuns para tintas e vernizes.

ISO 21227-1-2003 Tintas e vernizes, Avaliação de defeitos em superfícies revestidas usando imagens ópticas – Papel 1: Orientação geral

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

— Papel 1: Orientação geral

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

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

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

introduzir
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, preciso, quantitative and repeatable results.

ISO 21227-1-2003 Tintas e vernizes, Avaliação de defeitos em superfícies revestidas usando imagens ópticas – Papel 1: Orientação geral

1 faixa
Esta parte da 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 (por exemplo. lithotripsy, weathering or crosscutting tests). One goal of ISO 21227 is to use optical imaging to reproduce the results of existing visual evaluation methods. Além disso, optical imaging provides more information that can be used to assess coating defects in more detail.

Esta parte da 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 referências normativas
The following references are required for the use of this document. Para referências datadas, versões somente para citações se aplicam. Para referências sem data, a nova versão da referência (incluindo quaisquer revisões) aplica-se.

Publicação CIE Não. 17.4:1987, International Vocabulary for Lighting /IEC 60050-845:1987, International Vocabulary for Electricians – Iluminação

3 Termos e definições
Para efeitos deste documento, os seguintes termos e definições se aplicam.

3.1 Optical Imaging

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

3.2 Iluminação

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

[Fonte: 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

[Fonte: 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

[Fonte: 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 Propósito

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

ISO 21227-1-2003 Tintas e vernizes, Avaliação de defeitos em superfícies revestidas usando imagens ópticas – Papel 1: Orientação geral

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

Observação 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

Observação 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

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

3.4.5 píxeis

The minimum image forming element to which grayscale is assigned

3.4.6 Resolução

The number of pixels per unit length on an object surface

Observação 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

Observação 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

Exemplo: 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 para 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

Observação 1: Por exemplo, 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 (preto) ou 1 (branco)

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

ISO 21227-1-2003 Tintas e vernizes, Avaliação de defeitos em superfícies revestidas usando imagens ópticas – Papel 1: Orientação geral

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

Observação 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

Observação 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