Print image resolution calculation

1. Digital images processed by computers are also called "matrix graphics."
You can think of dot matrix graphics as a combination of square blocks of many different colors.
And each color square block is called a pixel.

2. Resolution refers to the number of dots or pixels in a unit of length of a digital image.
For example: An image resolution of 100 points per inch is called 1OODPI
(Dots Per Inch).

3. In each digital image processing software, each point is called a pixel.
So the unit of resolution is also called PPI (Pixels Per Inch).
Whether DPI or PPI (DPI, which is a more general unit),
From the impression of traditional photo printing, we can know that the finer the particles of film and photo paper,
The more vivid the image quality can be, the more delicate it will be.
Since digital images consist of pixels, naturally the higher the resolution,
(In other words, the greater the number of pixels per unit length, the better the digital image quality will be.)
Therefore, imagine the quality of the image represented by the 300 DPI digital imagery.
Absolutely better than 72DPI digital images.

4. Before scanning the image into a digitized electronic map file,
The output resolution and image magnification of the printed product must be determined first.

5. [Magnification] is the ratio of the print size of the image to the original size.

6. The print resolution is usually expressed in units of line per unit length (Line Per Inch).
Based on the type of print and the type of paper, roughly speaking:
Newspaper: 85lpi
Color Magazine: 133, 150 or 175 lpi
Art album: 200lpi

6. In general, when we use snow-copper paper and other relatively smooth papers as printing materials, we will choose
300pixels/inch (DPI) or 118pixels/cm (DPC) resolution for digital image printing. Such image resolution can be used to print up to 150 lines per line (150 Lines Per Inch).

7. Digital image resolution used on various types of prints,
It depends on the value of the printed cable used for the printed material.
If you want higher screen quality, the resolution of digital images needs to increase.
Generally, the network cable value can be doubled, which is the resolution value that the digital image should have.
If the image needs to be magnified, it must be multiplied by the magnification, as shown in the following formula:

Scanning Image Resolution = Number of Printed Wires x 2 x Magnification

For example: the number of printed lines is 150 lines, the image must be magnified by 3 times,
The scanning resolution must reach 9OODPI (150LPIx2x3 times).
Another example: When the printing network line is 175lpi, if you want to print the image with the original ruler,
It is best to scan the image with a resolution of 35 Oppi.
If you want to enlarge the image twice in size, you should use a scanning resolution of 70 Oppi.

7. When dealing with Line Art, the resolution of the output device should be used as the scanning resolution.
For example, to output 12OOdpi black and white photo paper, it should be 12OOppi scanning resolution.
If only 300dpi radioprinter is used for output, then 30Oppi is the scanning resolution.

Source: China Art and Design Alliance