Analysis and application of the hottest machine vi

2022-10-02
  • Detail

Analysis and application of machine vision in color image acquisition

preface

machine vision has been widely used in semiconductor, electronics, automobile, food, medicine, textile, transportation and other industries all over the world. In China, with the improvement of supporting infrastructure and the accumulation of technology and funds, the demand for industrial automation and intelligence using image and machine vision technology has emerged widely in all walks of life, and gradually began to be applied in the industrial field, such as drug detection and packaging in the pharmaceutical industry, printing color detection in the printing industry, PCB surface quality detection, LCD screen quality detection, etc. It can be said that machine vision has penetrated into all aspects of our life, production and work. However, with the more and more extensive application, the acquisition of gray image can not fully meet the needs of application, and the color image acquisition technology is particularly urgent and important. At present, the application of color image acquisition has been successfully introduced into the new generation of LCD display industry and PCB testing industry. So, how to realize the leap from gray image detection to color image detection

classification of color image components

generally, the common color image three primary colors RGB (red, green, blue) are suitable for color reproduction and are commonly used on displays and cameras, while the color system with "saturation/chroma/hue" as the standard is used for machine vision. The spring height: 100 ⑶ 00mm; In use. Therefore, color image processing and analysis software must be able to distinguish colorless (grayscale or black and white) components (saturation) from color components that describe color (color Europe is also the largest peek trading market and hue in the world), so as to explain color more intuitively and completely, which is very effective for detecting and segmenting color objects and removing light effects. Displaying the excellent hue component (H component in his color space) does not change the shading, shadow and brightness intensity of the object. Similarly, this hue component has its differences in color or physical objects. Therefore, when processing or analyzing color images, it is necessary to convert RGB images into another color space, such as LSH, ish or ysh

color image conversion

color conversion is a very time-consuming work. In order to solve this problem, the color map can fully meet the national standard gb/t229 ⑵ 007 rules of various temperature control indicators. The image analysis software adopts the high-resolution color query table mechanism; The query table is a set of numerical arrays, containing the corresponding relationship between input and output. As long as you pre calculate the query table, you can check the conversion of the application to each image

The operation value of the

query table can be used to convert images from one color system to another. In addition, it can also be set to apply user-defined conversion content, such as gamma compensation and color balance correction. In addition, some operations will "compare" the contents of the query table to avoid the need to store converted images. For example, when the image is still stored in RGB format, the H component of the image ish color space can be changed

color segmentation of color images

generally, in addition to the traditional color image processing functions, such as Bayer system to color space conversion or color balance correction, color image analysis software can also provide powerful color analysis functions, so that users can classify color objects and detect defects

"threshold" is the basic mechanism for segmentation, which can distinguish objects from the image background according to comparison. In the part of the color image, you can also freely specify the numerical range of specific objects. The user can choose the numerical range of each component, for example, only select "olive green" pixels according to the hue, plus loose recognition of saturation and chromaticity, so as to eliminate the light effect of the surface

another more effective way to distinguish different objects in the scene is to consider a specific set of colors and specify each pixel closest to these colors. The color image segmentation function allows you to specify the "level" (integer exponential value) of each pixel to decompose the color image in different regions

application extension of color image processing component library

the above easycolor color image processing functions are usually used together with other image processing component libraries. For example, color image threshold technology can be combined with easyocr, easymatrixcode or easybarcode component libraries to read characters, 2D matrix codes or barcodes on color printing or color objects respectively. The color image analysis technology can be combined with the easyobject component library of open evision to perform blob analysis on the segmented region. In addition, color image processing can also be integrated into other software modules of open vision, such as open evision's component library easymatch, which is specially used for gray-scale matching

other conversion functions of color image

other conversion functions of color image often include color balance (also known as white balance). Color balance will adjust the intensity of color in the whole area (generally red, green and blue primary colors), and the main goal of adjustment is to correctly present special colors, especially neutral colors. In machine vision applications, the color imbalance is mainly due to the type of light used, and it may also be due to the correction error of the image acquisition device

at the same time, the best Bayer to RGB conversion function, pseudo coloring function (to enhance the effect of presenting gray-scale images) and component expansion function are also the conversion functions required for color image processing

application examples

color image processing is most commonly used in the following industries, including: vegetable and fruit or packaged food detection in food processing industry, drug detection in pharmaceutical industry, FPD detection (flat panel display), PCB detection in electronic industry (printed circuit board), and printed matter detection in printing industry

latest trend

at present, the latest attractive market trend of color image acquisition applications is to implement color conversion through hardware

for example, euresys' grablink quickpack colorscan is compatible with the camera link line scan camera, and uses the FPGA on the motherboard to provide the function of accelerating image preprocessing for color scanning applications. These functions include: scanning delay compensation (reconstructing the real RGB image according to the moving speed of the object by collecting RGB images for many times, so as to eliminate the problem of color dislocation), light field nonuniformity correction (compensating for the uneven illumination in the image), query table and white balance correction, so as to greatly simplify and accelerate the scanning of color files or PCB detection

another example is that the new grablink quickpack CFA is compatible with camera link Bayer and RGB surface scanning cameras. The card has the preprocessing functions of Bayer decoding, white balance, brightness extractor and four LUT operations

euresys and ADLINK ADLINK are the only general agents of euresys in China. Relying on the professional experience of Linghua technology in the application of automatic detection and control, combined with the professional technology of partner euresys, they jointly put forward a complete machine vision solution, including image acquisition card, image analysis software, industrial camera and other complete sets of vision solution hardware, which can shorten the labor, material resources and time required by equipment manufacturers to verify performance. At the same time, combined with the motion control part, it provides all-round solutions, technical support and services such as motion control, high-speed trigger control, industrial computer platform, etc. the verified high reliability integration platform ensures the efficiency, shortens the time to market, and seizes the business opportunities of the new generation of optical detection equipment. (end)

Copyright © 2011 JIN SHI