Similarities and Differences Between Graphic Image Files for Printing and General Graphic Files

The biggest problem for many people is that they use the graphics file for printing as a web page. They are often miserable! The biggest problem with this is that you do not understand the characteristics and needs of printing. Maybe your computer drawing skill is first class, but if you want to use it for printing, please take a look at the following instructions:

● Resolution

The resolution of most people's computer screens is at most 12801024. After the conversion of the size of the screen, it is about 60 to 90 dpi, plus the light emission characteristics of the screen, so each pixel looks like a round glow point. The light blends together without noticeable graininess. However, the general color printing resolution is between 300 and 350 dpi, which can represent the details that are difficult to display on the screen. Therefore, the images seen on the screen are printed on the paper in the same size. Each pixel is printed out neatly. Block shape, get the print result of the mosaic. This is similar to the feeling of using LCD screens. Each point has its own corners. As shown below:

To avoid this situation, the resolution must be set between 300 and 350 dpi in order to make full use of the high quality of the printing. However, this will cause a sudden increase in the amount of stored data. The drawings are printed more than ten times larger than the screen. This is why the computer that specializes in printing and drawing needs to be equipped with high-capacity memory.

In fact, not all situations need to use 300dpi quality. For example, poster production, because the viewing distance is usually relatively long, if the pattern is not very particular, often use 100 dpi on it, which will save a lot of computer processing time, but you can see the mosaic at close range The effect is.

●Color mode

The computer's graphics file usually uses the RGB color mode. Since printing uses CMYK four-color inks, in order to ensure the quality of the printing, the color of the graphic file must be specified in CMYK to be accurate. With scanning, the problem is even greater, because you don't know what color the scanner sweeps in. What color it will turn into in actual printing, and the best way is to ask the manufacturer to scan it. In addition, the colors on computer screens are actually different from the printed colors. In particular, the difference in cyan color is the greatest. Therefore, professionals, such as screens, scanners, and printers, undergo careful color correction to ensure that the finished products and screens are Not too much difference, but most people do not have color correction equipment, the color is still indiscriminate use, but do not know the color is not printed.

●File format

In general, the graphics files on the computer use the JPEG compression format to reduce the storage capacity, but in the printing must use the completely uncompressed TIFF format! This is because the image quality caused by the compression may not be visible on the screen, but it can be seen clearly when printing. Because of the high resolution of the graphic files and their non-compression, documents of several tens of hundreds of megabytes are commonplace for printing. Unlike ordinary JPEG graphic files, there are several hundred K. Therefore, the industry usually uses a disc capacity (650 MB) as a file storage exchange.

● graphics file source

Referring to the printing profession is a feature that deals with high resolution images, so the source of graphic files used in the design must also be high resolution. This is the reason why each photo file for a dedicated graphic library is very large! Often, only one or two discs can be placed on a single disc. Some people are whimsical and want to use the maps captured on the Internet. The results are certainly predictable. If the pattern is scanned from newspapers and magazines, it is necessary to grasp a principle that the pattern can only be reduced and cannot be enlarged. Because the printed matter has outlets, the quality after scanning has dropped by one level, which is not as good as the original 300 dpi. Zoom in, the effect will be worse. Therefore, make sure that you have a suitable source of graphic files when you create.