What is a moire pattern? Beautiful shimmering moire

The production of “moire”, hammer, crackling, and “antique” coatings is based on the ability of certain paint and varnish materials during film formation, form beautiful patterns in the form of wrinkles, embossing or tears. Such coatings based on liquid paints have long been used in mechanical engineering, instrument making, the electrical industry and other industries. Recently, similar coatings have been produced using appropriate powder paints. Hammer coatings are especially popular, as they have a smooth surface that does not become dusty and weakly retains radioactive contamination.

Moire coatings (Fig. 11.5, A) obtained by using epoxy powder paint P-EP-135 in different colors. Similar

Paints are produced by many domestic and foreign enterprises. The corresponding wrinkled pattern is formed due to the presence of a special additive in the paint, which ensures different curing rates of the film former across the thickness of the coating. Paints are applied to the surface using electrostatic spraying; coatings (thickness 80-120 microns) are cured at 180 °C for 15 minutes.

Moiré coatings can also be obtained using liquid paints (MA-224 paint on compacted (polymerized) tung or oitisic oil). The coating technology in this case is much more complicated. Paints are applied to a pre-primed surface, usually in two layers with an interval of 5-10 minutes. The formation of the coating is carried out in two stages: at the first stage, the pattern is revealed, at the second it is fixed. Identification of the pattern is carried out at 80±5 °C for 25-40 minutes, the fixing operation is carried out at 100-170 °C depending on the type of paint and its color.

Hammer coatings (Fig. 11.5, B) By appearance resemble the characteristic patterns obtained by minting metal. This effect is achieved by introducing into liquid enamels non-floating (low-grease) aluminum powder and pattern formers, which are organosilicon compounds - silicone oils, SKT rubber, Vaseline KV-EM-1. The latter, by changing the surface tension of the film former, contribute to its “contraction” (collection into drops) on the surface of the substrate and powder particles. In this case, violation of the continuity of the coating is not allowed.

To obtain hammer coatings, the industry produces melamine alkyd (ML-165 and ML-165M), nitrate cellulose (NTs-221), alkyd styrene (MS-160) and other enamels. Along with aluminum powder, they contain small quantities of covering mineral or organic pigments, which give the color shade coating. Enamels are usually applied by spraying (1-2 layers) onto a previously prepared and primed surface. Before use, a pattern former is introduced into them in the form of a 10% solution in xylene at the rate of 1-10 g per 1 kg of enamel. A drawing (pattern) is formed immediately after applying enamel to the surface. It is fixed (coatings are cured) in the case of ML-165 and ML-165M enamels at 120 °C for 1 hour, NTs-221 - at room temperature within 24 hours

Powder paints (P-EP-258 and others) have also been developed to form hammer coatings. When using them, pattern formation occurs at the moment of coating formation due to surface effects in the film. They also contain aluminum powder. Depending on the type of color pigment, they form coatings of different colors and shades.

Hammer coatings made from liquid paints are used for finishing metal and wooden products: devices, movie cameras, sewing machines, cases for devices, etc. Powder paint coatings have the same purpose, but they are suitable for painting only heat-resistant substrates.

Cracked coatings (Fig. 11.5, IN) imitate the pattern of crocodile skin. To obtain them, both liquid and powder paints are used. The liquid compositions used are cellulose nitrate paints, which are highly filled systems that are diluted with highly volatile solvents, such as acetone. Cracking is caused by the low cohesive strength of the resulting films and large internal stresses that arise during the rapid volatilization of solvents.

Paints are applied over a background layer of cellulose nitrate enamels, the color of which is usually chosen to contrast with the color of the cracking paint. In thick layers the paint cracks with large tears, in thin layers it cracks with small ones. Cracking occurs immediately after applying paint to the surface. After drying from solvents, the coating can be covered with a layer of varnish or enamel.

Recently, these paints have practically lost their importance for environmental reasons and fire hazard. This niche has been firmly occupied by powder paints that are more convenient to use. They are obtained by introducing aluminum powder and special structuring additives into thermosetting powder compositions, which, by stretching the powder particles in the surface layer, imitate the state of a cracked film. Unlike liquid paints, powder paints practically do not create a surface relief (it remains smooth), which contributes to the non-contamination of coatings. The size of the pattern depends on the viscosity of the melt.

Cracked coatings have a purely decorative purpose. Sometimes they are used to finish dashboards, cladding slabs and panels indoors.

Textured coatings (Fig. 11.6) create the effect of a surface with a large “shagreen”, similar to coatings made from paints and varnishes with poor spreading. The most widely used coatings are textured coatings based on thermosetting powder paints. Regulation of film texture is achieved purely by prescription - by introducing additives that change

Rice. 11.7. Antique colored coatings:

A- with aluminum powder; B- with bronze; IN- with zinc powder

Viscosity of melts (aerosil, thermoplastic polymers, etc.). Coatings can be different color, containing reflective pigments and not containing them. An example of compositions of this type are epoxy-polyester paints P-EP-259-T-1 and P-EP - 259-T-2, produced by OJSC NPF "Pigment". The macrorelief of the coatings formed from them makes it possible to hide defects in the surface of metals - casting, stamping, small irregularities with a film thickness of 80-100 microns.

"Antiques" (Fig. 11.7). The term "antique" appeared in coating technology with the development large number powder paints containing flaked reflective pigments and fillers - powders made of aluminum, bronze, copper, zinc and other metals, as well as mica, pearlescent pigments, etc. Possibility of variation decorative effect Such coatings are practically unlimited. They are determined not only by the type of reflective component, but also by its dispersion, the method of introduction into the composition, the nature and amount of color pigments, and the presence or absence of structuring agents.

There are basically two methods of introducing flake pigments into powder compositions: before extrusion and after extrusion. In the first case, powder particles are chaotically distributed in the melt of the film former and, due to its high viscosity, lose the ability to float when producing coatings. A high reflective effect is achieved only in the second case, when the powder composition, after extrusion and grinding, is mechanically mixed with powder. Particularly attractive for obtaining compositions is the bonding process (mixing under moderate heat), in which powder particles are firmly attached to film-forming particles. This eliminates the separation of powder compositions when applied in an electric field. Any thermosetting film formers are suitable for producing antique-type coatings. The powder paint manufacturer Ekolon (St. Petersburg) has achieved particularly great success in developing formulations for such compositions.

Among other decorative coatings, special attention is deserved paint coatings called "chameleon". Their main feature is the change in color when viewed from different angles. Powder varnishes for chameleon-type coatings are produced on the basis of light-resistant polyester film formers with the use of special pigments, which are SiO2 compounds WITH microlayers of TiO2, Fe203 and 2Yu2. Such pigments are offered by the company "Megsk".

You've probably noticed in some photographs, especially when viewed on a computer display, interesting features, in the form of so-called “false detailing”. Typically, the appearance of false detail occurs due to errors in the graphics program, but the main reason lies in the quality of the image itself. At the same time, even a well-trained Photoshop user is sometimes unable to get rid of such defects.

So, what exactly are we talking about?

This phenomenon is called "moiré". It is caused by a third pattern, which in turn appears as an overlay of two slightly different images. For example, the first one belongs to a specific object (roof tiles, etc.), while the second one is a pattern on a sensor or PC screen.

What can be done in such a situation? Before you is one of the most serious technical problems in digital photography. True, screen moire does not deform the final image. And scene moire is generally a rather rare phenomenon; its effect on a digital image is insignificant, and it can always be neutralized with graphics software.

Screen moire

This kind of “banding” (marked with an indicator) appears when the image on the screen is slightly scaled, but you don’t have to worry: screen moire does not affect the quality of printing and copying of pictures.

Moire scene

Another manifestation of moire is false images that appear due to the interaction of the roof tiles and the camera sensor. Such a defect cannot be eliminated, but fortunately, it is very rare and is clearly visible only with a significant increase in the image.

The original photograph shows that in small photographs the moire is almost invisible.

"Scorched" and light fragments

In some photographs, bright areas appear white or almost white, significantly reducing the detail and color performance of the subject. This photo captures the Angkor Wat temple, the time is a sultry tropical afternoon, the scorching sun illuminates the smooth stones, which, combined with the contrasting deep shadows of the temple, makes it difficult for the photographer to get a high-quality photo. However, if you approach the construction of the composition thoughtfully, the situation can be saved.

The fact is that in some cases the brightness range is too large for the film or sensor, which leads to a significant darkening of the shadow areas of the scene and “burning out” of the illuminated areas.

To avoid the above-described shortcomings, do not take photographs in bright, contrasting conditions, relatively speaking - at noon. If this time of day cannot be avoided, try to include as few light spots as possible in the frame. Also work hard to create a composition that will not depend on subtle shades of color and shapes of objects.

How to remove moire from a photo? Complete removal of moire takes place in two stages. Let's remove the colored moire first, and then the patterned one.

Open our image in Photoshop:

1. Removing colored moire.

Make a duplicate of the main layer ( Ctrl+J). Change the blending mode to Color(Color).

Choosing a tool Brush Tool (Brush), preferably with soft edges. To do this, change the brush settings Hardness(hardness) by 0% . Click Alt and hold it, the mouse cursor will turn into a pipette. We click on the photo in the place where we do not have moire and there is a primary color corresponding to the one on which we will remove the moire.

Letting go Alt, and move on to removing moire: carefully paint over all the places where there is moire; periodically the brush color will need to be changed to a more suitable one. If suddenly the wrong area of ​​the photo is affected, we use Eraser tool (Lastic) or a mask.

Comparison of the initial image with the image after processing (clickable):

The colored moire was successfully removed, but in the photo there was a patterned moire all over the fabric. Therefore, below we will consider a method that will help us remove it.

2. Removing patterned moire.

Merge all layers ( Ctrl+E), and again create a duplicate ( Ctrl+J).

Let's go to the menu Filter->Blur->Gaussian Blur(Filter->Blur-> Gaussian blur), and increase the radius value until the moire stripes completely disappear. Let's see what value the parameter took Radius(Radius). In our example 10,5% . We remember it, but don’t apply the filter!

Let's go to the menu Filter->Other->High Pass (Filter->Others->Colorcontrast). For this filter, we set the radius value that we obtained earlier - 10,5%. Select blending mode Linear Light(Linear light) And Opacity(Opacity) — 50%.

Now let's invert the layer Image->Adjustment->Invert (Image->Edit-> Invert) or simplyCtrl+I. This is necessary so that the filter works to suppress, and not enhance, moire .

Now apply to this layer filter Filter->Blur->Gaussian Blur(Filter->Blur-> Gaussian blur). Slowly increase the blur radius from zero until the texture is preserved and moire does not appear and press OK.

Now you can experiment with Opacity(N opacity), in order to get a more suitable effect. It's okay if the image looks a little wrong. Assign a mask to our layer and fill it with black. Take the tool Brush Tool (Brush) we ask her White color and carefully use the mask to go through the places where there is moire.

Powder paints are now used for decoration big view surfaces. Sometimes we may not even notice that the structure in front of us was painted using powder paint. This, in turn, affects a large assortment presented products, each element of which has its own advantages and disadvantages. However, in most cases, the choice of powder paint type is determined by the scope of its application or, more precisely, the type of application surface. So, if you plan to place the structure outdoors, then powder painting with a polyester mixture is the best method, since it better protects the surface from sunlight and other weather conditions. In turn, epoxy analogues are suitable if increased resistance to chemical, acid or alkaline influences is required. Finally, epoxy-polyester combinations are great for indoor use. They not only lie very easily and smoothly on the surface, but also allow you to create various types of textures that open up great opportunities for decorating a room and creating a unique interior. Despite such diversity possible options, is most popular among painting specialists today moiré powder paint, which after spraying resembles to the touch orange peel. This popularity is due to several fundamental factors that distinguish this type raw materials from most of their analogues.

In general, the consistency of moire can be compared to very fine sandpaper. At the same time, the surface is velvety and shiny to the touch. In this case, the degree of gloss is adjusted by changing the saturation of the consistency of the paint composition. The minimum value is 20%, and the maximum is 40%.

The main advantage of moiré powder paint for metal is that it can easily hide any minor defects on a metal surface. This is often the decisive factor when faced with a choice between painting or replacing a particular part. Moiré gives the surface a matte tint, which appears already at a distance of only half a meter, which makes it a choice when there is insufficient funds for real matte powder paint. By the way, the price of moire paint is on average lower than any other analogue, which again is an argument in favor of choosing this particular type of powder raw material. Another advantage is that moiré powder paint very flexible to mixing with various additives, which cannot be said about most other analogues. Thanks to this, developments are currently underway to create a special type of moiré powder paint, which will have anti-vandal properties. In other words, surfaces coated with this coating will have increased strength and scratch resistance. This discovery should be a breakthrough in the automotive industry, which is why today investors are investing large sums in these developments. In addition, the possibility of mixing significantly expands the boundaries of the use of moiré powder paint. True, experts note that in its pure form this raw material is applied much better and creates a higher-quality coating, which cannot be said about its mixed modifications. That is why moire cannot yet compete at a decent level with other types of powder paint that are used in specific application conditions. In addition, this powder raw material still does not make it possible to create a smooth surface, which is so valued in the decorative arts. By the way, the roughness of the texture leads to another drawback, which is susceptibility to the rapid accumulation of dust, which complicates the process of caring for such a surface. However, in general moiré powder paint has the best characteristics of its kind, which make it so popular with many companies that specialize in coloring. Perhaps in the near future experts will find ways to level out the indicated disadvantages moire paints, and this one

A moire pattern is observed when superimposed on each other. various parts tulle curtains.

The concept of "moiré" comes from fabric moire?!, in the finishing of which this phenomenon was used.

Moiré pattern occurs when digitally photographing and scanning reticles and other periodic images if their period is close to the distance between the photosensitive elements of the equipment. This fact is used in one of the mechanisms for protecting banknotes from counterfeiting: a wave-like pattern is applied to the banknotes, which, when scanned, can become covered with a very noticeable pattern that distinguishes the counterfeit from the original.

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Digital image processing

The appearance of moire during scanning

In everyday life, moire often appears when scanning printed images. This occurs because the scanner re-rasterizes an image that already has the original raster in it. It can be more simply imagined this way: if you take a tracing paper with one ornament and put it on a tracing paper with the same ornament, but depicted from a different angle, then the resulting ornament will differ from both the first and the second. If you put them so that they coincide, then the first ornament will coincide with the second.

The round “rosettes” at the intersection of two rectangles result in image distortion, which is visible in the first picture.

The appearance of moire during the screening process

Moire can also occur due to incorrect setting of angles between the lines of primary colors during screening. Both are, in fact, the interference of two sets of raster lines. There are several types of moire rosettes, by the appearance of which you can often find out the cause of moire.

Scanning, in fact, is the modulation of signals in the scanner grid nodes by the brightness of the typographic raster nodes. IN general view the result is a product of two modulated sinusoids (gratings) with different periods of spatial oscillations. One