RU2375198C1 - Method for application of raster image - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention may be used in systems of laser marking and engraving in industry, for artistic applications, for authentication and personification of items and documents. Method for application of raster image consists in the fact that image of original is introduced into computer, image is transformed into raster array of numbers, working element coordinates are changed, working element is put in action, and dots are applied with its help onto surface of item. Working element used is represented by laser radiation. At the same time test image is previously downloaded into computer, and this image is applied onto surface of test sample, produced result is assessed, and laser radiation properties are accordingly adjusted in compliance with it. Multistage filtration of raster array of numbers is carried out, afterwards image of original is marked onto item.

EFFECT: high quality of applied image, increased resource of equipment, higher speed of image application, and also expansion of field of materials suitable for application of images.

6 dwg

Description

The invention can be used in laser marking and engraving systems in industry, for artistic applications, for authentication and personification of products and documents, as an alternative method in photography and printing.

The well-known "Method for improving digital images" [RF patent No. 2298226]. It consists in the fact that noise filtering is performed, global contrast is corrected, the brightness component is extracted from the color image as the maximum of R, G, B components, local parameters for dark and light tones are determined, bilateral image brightness is filtered and the dark and light are corrected tones in the brightness channel.

This method is not intended for processing images to be applied to any materials using laser radiation. This method does not take into account the properties of the materials of the substrate, the tool for applying the image and the features of the processes of their interaction.

The well-known "Method of laser marking" [RF patent No. 2146200].

It lies in the fact that by means of the action of a laser beam with a changing energy density of the laser radiation, a visible image is formed on the modifying layer. The image formed by the laser in different layers of the application can be a single unit, or in the form of an independent image for each layer and engraving on the glass. When marking, the laser beam removes the layers and cuts through the substrate and engraves the product.

In most cases, the quality of the received image is unsatisfactory.

The well-known "Method for adaptive rasterization of a grayscale original and device for its implementation" [RF patent No. 2308167]. It consists in the fact that a two-dimensional signal tone of the image, consisting of multi-level values of the tone signal of the sections of the original, is converted into a two-dimensional signal of the raster copy, consisting of two-level tone values of its printed and white space elements. For this, two types of two-dimensional signals of the weight values of the elements are formed. In the first of them, the weight values are distributed between the elements in any order, independent of the nature of the tone change, and in the second, taking into account the geometry of its contours. A two-level tone signal of the raster copy is formed taking into account its value by comparing the signal values of the original sections with the weight values of both types. The second type of two-level signal is placed inside spatial intervals, the position of which is determined by generating a path trace signal, and the boundaries of the segments are set depending on the number of surrounding elements.

This method requires a long manual selection of equipment settings and image processing. The method does not allow obtaining images on the surface of various materials with a quality comparable to photographic.

Known "Device for applying a grayscale image on a flat surface of a polished product", which implements the method of applying the image selected for the prototype [RF patent No. 2141444].

The method is as follows: the image of the original is entered into the computer using a scanner. Convert the original image to a raster array of numbers. The raster dataset contains information about the number of lines in the raster scan, as well as information about the geometric dimensions of the transferred image, the brightness and mechanical characteristics of this type of material. Change the coordinates of the working body (percussion instrument), while bringing it into action. Using a working body, mechanically apply points to the surface of the workpiece, the size and location of these points being determined by the image properties of the original.

The disadvantages are the low working speed, the small equipment resource due to the intense mechanical interaction of the working body with the material of the workpiece, the ability to process only flat surfaces, the low resolution of the images obtained due to the large size of the obtained points.

The objective is to improve the quality of the applied image, increase the life of the equipment, increase the speed of applying the image, expanding the range of materials suitable for applying images.

A method for applying a raster image is proposed, which consists in first downloading a test image, which is a raster array of numbers, to the computer and applying a test image to the surface of a test sample of the same material as the main material, evaluating the result, and choosing the parameters of the best image. Laser radiation is used as a working member and its properties are adjusted in accordance with the selected parameters. Next, the original image is introduced, this image is converted into a raster array of numbers, multi-stage filtering of the array of numbers is performed, and then the filtered image of the original is marked on the product.

A test image is downloaded to the computer using the laser equipment control program. A blank of the same material and with the same surface condition as the product on which the image is to be applied is placed in the working area of the marking laser equipment. Set up laser equipment and apply a test image using the laser equipment control program. In this case, the working point of the focus of laser radiation moves along the surface of the workpiece in accordance with the program. Simultaneously with the shift of the focal point of the radiation, the parameters of laser radiation change in time, due to which the effect of laser radiation on the surface of the workpiece changes. Using a microscope or magnifier, visually evaluate the result of marking. Of the various elements of the test image, those are selected whose contrast is greatest while there is no trace of carbonization, melting or changing the shape of the surface of the workpiece. The laser radiation parameters and the distance between the points at which the selected test image element is obtained are recorded. These parameters are introduced into the laser equipment control program. If necessary, the measured parameters with reference to the type of material are recorded in the technological database for future use without re-applying the test image to the workpiece. Also, an original raster color or grayscale image, which must be applied to the surface of the product, is introduced into the laser equipment control program. Perform automatic processing - multi-stage image filtering according to a special multi-stage algorithm with simultaneous conversion to a bitonal format according to a known method [Pratt W. "Digital image processing" M .: Mir, 1982]. The product is placed in the working field of the laser equipment for applying the desired image on it and the image is marked on the surface of the product. As a result of marking, the laser beam bypasses sequentially all points of the applied image, forming a visible grayscale image on the surface of the workpiece.

The original image deposited on the surface of the product, due to the preliminary determination of the properties of the interaction of laser radiation with the selected material and due to multi-stage filtration, has an increased quality, namely, the maximum reliability of the obtained image. The use of a working body - laser radiation instead of a shock body allows you to increase the resource of the equipment, increase the speed of applying the image and expand the range of materials suitable for applying images.

As an example, consider the process of applying a photographic image to a blackened aluminum plate. To apply the image, we used the laser marking complex DMark-06RL of the company TsLT LLC St. Petersburg with a radiation length of 1064 nm, an average power of 6 W, and a working field of 110 × 110 mm.

1. Drawing a test image. A blackened aluminum plate was placed in the working area of the laser equipment. A pre-prepared test image in the form of a set of points located in the nodes of linear grids with different pitch from 20 μm to 1 mm was downloaded to the control program computer into a computer (Figure 1). The program is launched. In this case, the test image is transferred to the surface of the plate with a laser beam. (Figure 2)

2. Assessment of the parameters of the test image. The operator considers the test image obtained with the naked eye, and with the help of a powerful magnifier or a microscope. A test image element is selected that satisfies the conditions for the maximum value of the contrast parameter without signs of carbonization or melt of the material. (FIG. 3) The parameters of the grid corresponding to the selected element (grid step, diameter of the elementary point) and laser equipment settings (radiation power, modulation frequency, number of pulses per point) are saved by the operator for subsequent use in the processing of the original image and for laser equipment settings .

3. The obtained parameters are a mesh pitch of 50 μm, the diameter of a point of 50 μm is transmitted to a software module (filter). At the same time, according to the obtained parameters - the radiation power is 48% of the maximum, the modulation frequency is 70 kHz, the number of pulses per point - 1 sets up the laser equipment.

4. Conduct automatic multi-stage filtering of the source image (Figure 4) using a software module (currently part of the M-Script program) that performs the following operations:

Intermediate processing results are shown for illustrative processing.

4.1. Make a preliminary correction of the brightness and contrast of the image. If necessary, information about the color is destroyed (the image format is converted from color to grayscale).

4.2. The entropy of the image is calculated and extra information is removed from it.

4.3. The image brightness and contrast are again corrected (histogram scaling).

4.4. Taking into account the parameters measured using the test image, the image contours are amplified.

4.5. The image is converted to bitonal format.

4.6. Thinning and noisy images. The resulting image (Figure 5) is ready for application using laser equipment.

5. Apply the image. A plate is placed in the working area of the laser complex on which the image will be applied. The processed image is loaded into the equipment management program and marking is made to obtain the final image in the form of a grayscale raster image (Fig.6).

6. Evaluation of the quality of the image. The resulting image is perceived quite well as a medium quality photograph. Sometimes it is possible to slightly improve the result due to additional selection within a small range of parameters of laser radiation. The image on the left was obtained by laser marking by converting the image into a bitonal format by standard means without preliminary processing. The image on the right was obtained by laser marking using the algorithm considered here, taking into account the properties of the process of interaction of laser radiation with the material. The received images of the original are of good quality, close to photographic.

Claims (1)

The method of applying a raster image, which consists in the fact that the image of the original is entered into the computer, the image is converted into a raster array of numbers, the coordinates of the working body are changed, the working body is brought into action and points are applied to it on the surface of the product, characterized in that as a working of the organ use laser radiation, first a test image is loaded into the computer and this image is applied to the surface of the test sample, the result obtained is evaluated, and in accordance with this They have the properties of laser radiation, perform multi-stage filtering of a raster array of numbers, and then mark the image of the original on the product.

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