How the quality of a printed image is formed: pixels, resolution, lineature and other scary words.

To obtain a high-quality, clear image when printing, you must have a good original image. Several factors affect image quality. Let's look at which ones.

What is a pixel

< p>The first thing you need to understand when creating a design for printed products is the nature of the image. In graphic design there is the concept of raster and vector graphics. In vector graphics, an image is a mathematical description of geometric objects (“primitives”). In raster - a grid (matrix) of dots of different colors. These smallest elements of a picture are called pixels (short for pictures element). Raster images allow you to achieve smoother transitions of halftones, therefore they are preferable when preparing files for printing.

File format

Raster files are quite large size. Their description (location and color of the dots), as well as the compression algorithm, is the very file format, say .jpg, .gif, .png, .tiff, .bmp. Please understand that they are not all equally suitable for printing. For example, JPEG uses lossy compression and the files themselves are very small in size. This means that such a file is better suited for web design or network transmission, but not for printed reproduction. At the same time, for example, TIFF supports various compression settings, both lossy and lossless. The print quality of such a layout will be significantly higher.

Image size

Each image has its own size. However, in printing this concept has several meanings. In addition to the linear size of the finished product in millimeters or centimeters, the number of those same pixels placed vertically and horizontally within the image is important. This is called resolution. The more of them in a smaller area, the better. In other words, a business card file with a format of 90x50 mm with a resolution of 1900*1024 will be printed more clearly than a banner with a size of 2x3 m with a resolution of 640*480. In the latter case, the pixels when printed will be larger and they will be visible and the image itself will be very blurry.

Lineature

The ratio of the number of dots (screen lines) of an image and its length is called lineature and is measured in lines per inch lpi or dots per inch dpi. This value is the main indicator of image quality in printing. Therefore, the printing house often insists on certain indicators in the requirements for layouts for printing. Let's say, if you need a file with a resolution of 600 dpi, that is, there should be 600 pixels per square inch of the image. In most cases, this resolution will make it possible to obtain a high-quality file when printing.

Color model

Another important criterion for the quality of a layout is the color model. It should be noted that most often the RGB (red, green, cyan) system is used to describe color in cameras and monitors, and CMYK (blue, magenta, yellow, black) is used in printing. In both cases, all the shades of color in an image are obtained by mixing three or four primary colors. These palettes are not identical, so when preparing a file for printing, it is very important to convert the image to the desired color model. Otherwise, the final printed color will differ significantly from the designer’s intention. In special cases, where a very precise (say, corporate) color is important, it is worth asking the printing house for the opportunity to use a color from the expanded Pantone color palette.

So, when preparing a layout for printing, you should pay attention not only to beautiful pictures. They also need to be carefully processed, having previously studied the requirements of the printing house, which will certainly include resolution and color model. This is the only way you can get the finished result without distortion, loss of quality and color. The ideal option is to turn to professionals. Designers working in the printing house will help you prepare a truly high-quality layout.