Almost every modern user of a PC and mobile gadgets is roughly oriented in the resolutions of anything and is able to distinguish between a camera with a better matrix, a monitor with a better picture and a video with better quality by the number of pixels.However, when transferring content from “numbers” to live paper, many people have problems.
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Print Resolution
Actually, the snag is that when printing, we have a new variable that the average user is not familiar with – print resolution.Only a narrow specialist involved in printing, advertising, photo printing, etc., can easily name the minimum required resolution to create a physical image on a huge billboard, a small business card or a printed T-shirt.In this material, we will focus on common examples of printing that each of us may encounter in everyday life (printing on A4, A3, A2, A1, A0 sheets), and also derive a simple formula for calculating the required resolution for any given task .
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What is DPI
So, print resolution is measured in DPI (dots per inch), that is, in the number of dots per square inch (1 inch = 25.4 mm).The easiest way to explain this parameter is to use an example of the principle of operation of such an outdated device as a dot matrix printer – in this case, DPI corresponds to the number of strokes of ink needles in an area of 1 × 1 inch.
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How many pixels do you need for high quality printing
Naturally, the DPI parameter has absolutely no meaning while the image remains on your monitor, but the resolution of the source file is a critical indicator.You will not be able to print a high-quality photo on A4 paper at 300 DPI if the original image on the screen has a resolution of 1024 × 768 pixels.
Standard DPI values used in printing
Resolution 75 DPI – for text documents;
Resolution 150 DPI – the minimum quality for printing images;
300 DPI is the generally accepted quality for photo printing.
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What size in pixels do A5, A4, A3, A2, A1, A0 sheets have, depending on DPI?
Below you can find a correspondence between the resolution values of the original image and the dimensions of the sheet of paper that is being printed on (the data is calculated for a print resolution of 75 DPI, 150 DPI and 300 DPI).
A5 size (148 × 210 mm) in pixels
at DPI = 75, A5 format resolution has 437×620 pixels;
at DPI = 150, A5 format resolution has 874×1240 pixels;
at DPI = 300, A5 format resolution has 1748×2480 pixels.
A4 size (210 × 297 mm) in pixels
at DPI = 75, A4 resolution has 620×877 pixels;
at DPI = 150, A4 resolution has 1240×1754 pixels;
at DPI = 300, A4 resolution has 2480×3508 pixels.
A3 size (297 × 420 mm) in pixels
at DPI = 75, A3 resolution has 877×1240 pixels;
at DPI = 150, A3 resolution has 1754×2480 pixels;
at DPI = 300, A3 resolution has 3508×4961 pixels.
A2 size (420 × 594 mm) in pixels
at DPI = 75, A2 format resolution has 1240×1754 pixels;
at DPI = 150, A2 format resolution has 2480×3508 pixels;
at DPI = 300, A2 format resolution has 4961 × 7016 pixels.
A1 format size (594 × 841 mm) in pixels
at DPI = 75, A1 format resolution has 1754×2483 pixels;
at DPI = 150, A1 format resolution has 3508 × 4967 pixels;
at DPI = 300, A1 format resolution has 7016×9933 pixels.
A0 format size (841 × 1189 mm) in pixels
at DPI = 75, A0 format resolution has 2483×3511 pixels;
at DPI = 150, A0 format resolution has 4967 × 7022 pixels;
at DPI = 300, A0 format resolution has 9933×14043 pixels.
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How is the number of pixels corresponding to the size of a sheet of paper determined?
As mentioned above, a print resolution of 300 DPI is considered to be sufficient quality for transferring graphics to paper.To print a photo or just a picture in this quality on an A4 sheet (297 × 210 mm), you must have an original image with a resolution of 3508 × 2480 pixels, if the quality requirements are halved to 150 DPI, then the original resolution of 1754 × 1240 pixels will be sufficient, and 75 DPI and a resolution of 877 × 620 pixels are enough to print text.
In any non-standard situation, you can resort to forbidden tricks and use mathematics.For example, to find out the required resolution of the original image for printing, we can build the following formula:
R = L × DPI / 25.4
Where:
R – the required permission of the party;
L — side length in mm;
DPI — the required print quality;
25.4 – convert inches to centimeters (1 inch is approximately equal to 2.54 cm) and multiply by 10 to convert to millimeters.
Example:
The photo needs to be printed at 150 DPI on A4 (297 × 210 mm) paper.We get:
R (height) = 297 × 150 / 25.4 = 1754 pixels;
R (width) = 210 × 150 / 25.4 = 1240 pixels.
Accordingly, the original resolution should be 1754 × 1240 pixels, which is the same as the data in the above table.
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