BS ISO IEC 15415 pdf download.Information technology — Automatic identification and data capture techniques — Bar code symbol print quality test specification — Two-dimensional symbols
1 Scope
This International Standard specifies two methodologies for the measurement of specific attributes of two-dimensional bar code symbols, one of these being applicable to multi-row bar code symbologies and the other to two- dimensional matrix symbologies; defines methods for evaluating and grading these measurements and deriving an overall assessment of symbol quality; gives information on possible causes of deviation from optimum grades to assist users in taking appropriate corrective action. This International Standard applies to those two-dimensional symbologies for which a reference decode algorithm has been defined, but its methodologies can be applied partially or wholly to other similar symbologies. While this International Standard can be applied to direct part marks, it is possible that better correlation between measurement results and scanning performance will be obtained with ISO/IEC TR 29158 in combination with this International Standard.
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 19762-1, ISO/IEC 19762-2, ISO/IEC 15416 and the following apply. 3.1 binarised image binary (black/white) image created by applying the Global Threshold to the pixel values in the reference grey- scale image 3.2 effective resolution resolution obtained on the surface of the symbol under test, normally expressed in pixels per millimetre or pixels per inch, and calculated as the resolution of the image capture element multiplied by the magnification of the optical elements of the measuring device 3.3 error correction capacity number of codewords in a symbol (or error control block) assigned for erasure and error correction, minus the number of codewords reserved for error detection 3.4 inspection area rectangular area which contains the entire symbol to be tested inclusive of its quiet zones 3.5 grade threshold boundary value separating two grade levels, the value itself being taken as the lower limit of the upper grade 3.6 module error module of which the apparent dark or light state in the binarised image is inverted from its intended state 3.7 pixel individual light-sensitive element in an array [e.g. CCD (charge coupled device) or CMOS (complementary metal oxide semiconductor) device] 3.8 raw image plot of the reflectance values in x and y coordinates across a two-dimensional image, representing the discrete reflectance values from each pixel of the light-sensitive array 3.9 reference grey-scale image plot 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 by convolving the raw image with a synthesised circular aperture 3.10 reflectance margin measurement of modulation using error correction and known module colours 3.11 sample area area of an image contained within a circle 0,8X in diameter, X being the average module width determined by the application of the reference decode algorithm for the symbology in question or, where the application permits a range of X dimensions, the minimum module width permitted by the application specification
5 Quality grading
5.1 General The measurement of two-dimensional bar code symbols is designed to yield a quality grade indicating the overall quality of the symbol which can be used by producers and users of the symbol for diagnostic and process control purposes, and which is broadly predictive of the read performance to be expected of the symbol in various environments. The process requires the measurement and grading of defined parameters, from which a grade for an individual scan (scan reflectance profile grade or scan grade) is derived; the grades of multiple scans of the symbol are averaged to provide the overall symbol grade. As a consequence of the use of different types of reading equipment under differing conditions in actual applications, the levels of quality required of two-dimensional bar code symbols to ensure an acceptable level of performance will differ. Application specifications should therefore define the required performance in terms of overall symbol grade in accordance with this standard. The guidelines in Annex D.4 are provided as an aid in writing application standards which employ this standard. This standard defines the method of obtaining a quality grade for individual symbols. The use of this method in high volume quality control regimes may require sampling in order to achieve desired results. Such sampling plans, including required sampling rates are outside of the scope of this international standard.
BS ISO IEC 15415 pdf download
