Mostly pixel graphics are used, as this is the only way to make a small image crisp on the small screen resolutions that are typical for these devices.
Distinctive features of pixel art
It is a common misconception that any drawing or sketch made using raster editors is pixel art. This is not true, a “pixelated” image differs from a “non-pixelated” one by technology - by manually editing the picture pixel by pixel. Therefore, pixel art differs from other types of computer art in its small size, limited color palette, and (generally) lack of anti-aliasing.
Pixel graphics use only the simplest tools of raster graphics editors, such as "pencil", "straight" or "fill". Therefore, there are masterpieces of pixel art made in Microsoft Paint and other non-full-featured editors.
In any case, the use of non-pixel-based tools (such as the Brush) and automatic filters (such as anti-aliasing) are considered unacceptable in "real" pixel art - such tools add new pixels automatically, violating careful manual placement. The "rule of good taste" is to use the minimum number of colors; ideally - standard 16 colors available on the vast majority of video subsystems, even the earliest ones: they encode three bits R,G,B signals and the fourth bit encodes brightness.
Pixel art is reminiscent of some classic fine arts such as cross stitch, mosaic, and beadwork—as the design is made up of small colored elements, similar to the pixels of modern monitors.
Advantages
- One of the easiest computer art styles to learn (a simple pixel art can be drawn without any special artistic ability).
- A natural choice for limited palettes and ultra-low resolutions where every pixel counts.
- Requires little memory due to the use of palette formats with a small number of colors.
- Even with very poor color reproduction, the pixel pattern does not lose its expressiveness.
- Looks good on screens with sharp pixel boundaries (like LCDs).
Flaws
- In the era of hicolor monitors and video co-processors with hardware alpha blending, other styles look more expressive (although at low resolutions you still have to align lines to pixels).
- Poorly tolerates automatic scaling (when you change the resolution, the picture needs to be redrawn). On modern (2016) PCs, the resolution of monitors is high enough to run a pixelated game in full screen at a scale of 2:1 or more (see below); if this is not possible, it remains only to run the game in a window.
- On poor quality monitors (interlaced CRTs, some LCDs with analog input), the "grid toning" (see below) may flicker.
Drawing methods
Drawing usually begins with a sketch, which consists of basic lines and defines the nature of what the artist intends to depict. It can be obtained by tracing a scanned drawing, and quite often they are shared by other artists. There are other methods, some of which resemble conventional drawing.
The limited palette requires the use of blur to achieve different colors and shades, but due to the nature of pixel art, this is only done by hand. Sometimes you can even find anti-aliasing "handmade" - including with a PNG format alpha channel, which allows you to overlay an image on any background.
Here are some examples of using the above techniques:
1. The main form of blur - "mesh toning" or dithering - two colors in the form of a "checkerboard" of 2 × 2 pixels. Changing the density of each color allows you to get halftones. Also, “checkerboards” of 2 × 2 pixels allow you to create the illusion of a large number of shades. 2. Stylized blur with randomly scattered squares of 2x2 pixels allows you to achieve unusual effects. Small circles can also be used. 3. Smoothing Anti-aliasing) - hand-drawn with anti-aliasing effect.Storage
Pixel art is usually saved in "lossless" formats, that is, those that can save every pixel in an image without loss of fidelity. Since there are few individual colors in a pixel art, palette formats are often used. PNG and GIF are examples of formats that meet these requirements while saving disk space.
They try not to save pixel art in JPEG format, since "lossy" compression is not suitable for pixel art elements, even if compression is minimal. The JPEG compression algorithm can cause a serious distortion of the original look of a pixel art due to the fact that it can change the colors of individual pixels. In terms of size, JPEG files with such drawings are even larger than those saved in GIF or PNG. BMP and other uncompressed formats are rarely used: palette formats with lossless compression (GIF, PNG-8) give a smaller file size without leading to loss of quality.
Classification
Flat pixel art refers to a front, top, or side view.
Isometric pixel art drawn in a projection close to isometric. Examples can be seen in games that display 3D space without using 3D processing. Technically, isometric angles should be 30° from horizontal, but lines look jagged in pixel art. To eliminate this effect, lines with a pixel ratio of 1:2 are selected, and the angle is 26.565° (arc tangent of 0.5).
Less common other projections- dimetric or perspective.
Story
Communities
There are many communities dedicated to pixel art on the Internet. Artists post their creations hoping to get constructive criticism and feedback to improve their skills. Pixel competitions are held in which players must create one of the square or hexagonal elements of a large picture, while making life as difficult as possible for those who will draw neighboring elements.
Sometimes there are tasks of drawing "on the topic", in which artists create their work according to a given template or on a specific topic. Some of these works can then be combined into one big picture.
Pixel dolls are extremely popular: one artist draws a template for a doll (usually with deformed proportions), others give the doll facial features, hairstyle, and outfit. It is considered bad manners to dress a doll in other people's accessories (" frankendolling").
Automatic scaling algorithms
Pixel graphics don't handle resizing well; when switching to another resolution, it has to be redrawn. Conventional scaling algorithms like bilinear and bicubic interpolation are designed for photographs and are completely unsuitable for pixel art - the picture becomes blurry. However, there are algorithms that increase the clarity of graphics on high resolutions. Modern computers can execute these algorithms even in real time.
Integer times increase
The simplest algorithm suitable for increasing by 2, 3, etc. times is "nearest neighbor". Some of the algorithms that automatically add details to a picture are:
- EPx (Scale2x) - Eric's Pixel Expansion
- SaI - Scaling and Interpolation
- Eagle ; SuperEagle
With non-integer coefficients
Algorithms with non-integer coefficients that automatically “think up the details” are not known at the beginning of 2016. However, there are several techniques for scaling a non-integer game.
Pixel graphics powered by wikimedia
Pixel colors with non-zero values can be selected from three hardware palettes, the definitions of which are given in Table 1. 3.2. These palettes are called hardware palettes because you cannot programmatically change the composition of the colors included in them.
Pixel colors in 640x200 and 640x480 two-color modes are controlled using DAC color registers. Pixels whose values are 0 are always displayed through the DAC's O color register.
Using the GET operator, information about the color of the pixels located in the rectangular area of the screen with the coordinates of the left top corner(xl, yl) and the lower right corner (x2, y2) is stored in a numeric array with the specified name.
In 320x200 4-color mode, bits 3 - 0 define the background color (i.e. the color of pixels with a value of 0) as well as the border color. In the CGA adapter, these same bits 3 - 0 determine the border color in text modes.
Now it remains to encode the colors of each pixel with numbers - and the problem of encoding the image will be solved: the encoded colors of the pixels, listed in order (for example, from left to right and top to bottom), will encode the picture.
In graphics modes, each character is written to a rectangular area of the video buffer according to the size of the character matrix. The value in the BL register determines the color of the foreground pixels. In the 256-color 320x200 mode, the content of the HH register specifies the background value, and in all other modes, the HH register specifies the video buffer page, so the background value is assumed to be zero.
Pixels with a value of 00b are always displayed with the color determined by the color selection register (port 3D9h) and are commonly referred to as background pixels. Thus, it is not possible to set the border color and background pixel color independently here.
Still, bit 7 of the attribute byte can control character flicker or background pixel intensity. However, in the EGA adapter, the flicker enable bit is bit 3 of the attribute controller mode control register (register 10h of the 3SOI port). When the flicker enable bit is in the 0 state, i.e. flicker is disabled, all 16 palette registers are available for background pixel colors.
By default, the pixel color is white. Recall that the same register in text modes sets the border color (see Sect. Therefore, when setting the mode by direct programming of the CRTC controller registers and the mode control register, it is necessary to avoid chaotic changes in the border color or pixel colors by programming the color selection register accordingly.
The Mode argument can take one of two values. If Mode0, then the pixels lying on the straight line segment override the pixels on the screen and the line on the screen has the current color. If Mode1, then the pixels forming the line have a color code equal to the result of the XOR operation on the codes of the current color and the color codes of the pixels on the screen through which this line passes.
At the same time, the attribute decoder circuits form the necessary symbol attributes - color, brightness, flicker. The accepted way of representing text data provides independent control of the attributes of each character on the screen. The colors of the foreground and background pixels are determined by the low and high tetrads of the attribute byte.
If you want to exchange an already purchased monitor with dead pixels, then keep in mind that there is international standard ISO 13406-2 governing the amount allowed defective pixels on the LCD monitor. Thus, the seller may refuse to exchange your monitor or refund your money if the number of defective pixels in .
1Permissible number of defective pixels on the monitor
The allowed number of defective pixels depends on the display class (pixel fault class). ISO 13406-2 defines four classes: first does not allow the presence of defective pixels. As a rule, all modern LCD monitors belong to second class. Below you can calculate the allowable number of defective pixels in accordance with the ISO 13406-2 standard for monitors second class:
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Note. In the calculation, the fractional number of defective pixels is rounded up to an integer by discarding the fractional part.
The ISO 13406-2 standard distinguishes the following defects: permanently lit white pixels (type I), permanently unlit black pixels (type II), sub-pixel defects (type III), which appear as colored permanently lit / non-lit pixels of primary colors (red, green , blue, cyan, magenta, yellow).
In addition, for resolutions of 1 million and above, the accumulation of color defective pixels (type III) is allowed side by side in a 5 x 5 pixel square. Such a defect is called a cluster. Second class monitors does not allow the presence of 5 x 5 clusters with type I or II defective pixels. For more details see.
In practice, this a large number of defective pixels as specified in ISO 13406-2 are extremely rare. The wide tolerance can be explained by the fact that the standard was developed in 2000. Since then, liquid crystal panel technology has improved.
2How to check your monitor for dead pixels
Examination LCD monitor on the presence of defective pixels is to carefully examine the screen for abnormal pixels. Inspection is carried out sequentially for the primary colors: black, white, red, green, blue, cyan, magenta and yellow.
Pixel(from the English picture element) - the minimum element of the image, which is a light spot on the display screen and takes on different shades. The main "brick" from which all computer images are built, regardless of its complexity. The image on the monitor screen is a collection of pixels.
Pixels are arranged on the screen in rows and columns. The screen resolution is determined by the number of pixels in each row and in each column. A 640 x 480 screen (standard resolution for IBM PCs and other compatible PCs equipped with VGA video adapters) displays 640 pixels horizontally and 480 pixels vertically. By modern standards, 640x480 resolution is considered low. Most new PCs provide a resolution of 1024 by 768 or higher.
You can change the color of each pixel independently, but the number of shades that can simultaneously be present on the screen is limited and depends on the used graphics hardware. Maximum amount colors displayed simultaneously on the screen is determined by the number of bits allocated for each pixel in the video buffer. In full-color systems, each pixel is assigned 24 bits of color information: eight for the red component of the color, eight for the green and eight for the blue.
Each eight-bit value ranges from 0 to 255, and higher numbers correspond to brighter colors. The 24-bit number can range from 0 to 16,777,215. By mixing red, green, and blue colors of different intensities, you can get almost any color. On systems with 256 colors (only 8 bits per pixel), the value from the video buffer points to one of the 256 rows in a table called the color palette. The number in this palette row specifies the color of the pixel. If the palette consists of 24-bit values, then the video card, in principle, can represent any of the 16.7 million colors.
Stages of information transformation:
■ The starting point of an image when it is displayed on a computer screen is the video buffer.
■ The color of a pixel is determined by the bits in the video buffer. By changing the 1s and 0s that a pixel is represented in the video buffer, a program running on the computer (such as a word processor or spreadsheet processor) changes the color of the pixel.
■ The inside of the screen is dotted with a luminescent material called phosphor. Each pixel consists of three phosphors: red, green and blue. The phosphor begins to glow when an electron beam hits it and continues to glow for some time (usually a few thousandths of a second) after the impact of the electron beam has ceased. Combinations of different intensities of red, green, and blue phosphors produce a variety of hues and color intensities.
■ A special device called a digital-to-analog converter (DAC) in the video adapter converts video buffer bits into voltage levels for the monitor's three electron guns.
■ For pixel illumination, the video adapter uses the voltage levels calculated in the DAC to control the beams emitted from all three guns. Each gun ejects an electron beam into the screen.
■ To aim the guns at their respective phosphor spots, the electron beams pass through the holes in the shadow mask on their way to the screen. The distance between these holes determines the spacing between pixels on the screen, which is called monitor pitch.
There are two types of masks: shadow and slit, with the former being more common. Shadow mask (shadow mask) is used in most monitors. As a rule, the more pixels on the screen, the higher the quality of the image. 
The illustrations show how images are displayed on a computer screen, and how the resolution and number of colors affect image quality. The minimum distance between phosphor elements of the same color is called dot pitch and is an estimated image quality index. Dot pitch is usually measured in millimeters (mm). How less value dot pitch, the higher the quality of the image displayed on the monitor. The best shadow masks are made of invar, which, when heated by electrons, does not deform.
In the shadow mask, the phosphor elements are located in vertical cells, and the mask is made of vertical lines. The vertical stripes are divided into cells which contain groups of three phosphor elements in three primary colors. The minimum distance between two cells is called the slot pitch. Accordingly, the smaller the slit pitch value, the higher the image quality on the monitor.
The result of all this is the image on the computer screen. The main purpose of a graphics program that runs on a computer is to put the correct values into the video buffer.
Literature
1. Jeff Prouse "Image Processing".
2. M.N. Petrov, V.P. Molochov "Computer graphics".