This side shows how combining Cyan, Magenta, yellow and black can give us a range of colours. Shapes and text will look like this in the ‘artwork’ format, and only when output to print does the halftone dot and the lines per inch come into play. This side shows how these colours are mixed using halftone dots. This simulation is how the majority of halftone printing techniques will look when inspected close up. Each colour (cyan, magenta, yellow and black) has its own angled pattern so that the colours are able to make a regular pattern/blend together, if they didn’t have an angle to each halftone screen then each colour would simply print on top of each other giving just black. Halftones, dots and halftone screens When halftone printing is accurate, the 4 colours will make a regular pattern with the appearance of circles. Here you can see each screen has it’s own angle. 1 Inch Why should I care about Lines Per Inch? In the image simulation above, we can see the dots quite clearly. My horizontal black lines align to the ‘dots in a line’ on the black halftone screen, so you can count a crude 18 lines (of dots) per inch (lpi). The optimum lpi will depend on the material onto which you are printing and is generally decided by your supplier/printer unless you state it. A number of factors (ie method of printing and onto what sort of material) decide how many lines per inch are suitable or achievable. Ideally, the highest possible number of lines per inch should be used, so that the pattern of dots is not a distraction to the eye. Unlike the crude lpi above which would be suitable for the side of a Jumbo Jet. • T-shirts (printed with a Screen Print method) are usually around 50-70 Lines per inch. • A newspaper (printed using a Lithographic Technique) is printed at around 90-110 lines per inch. • Magazines (printed using a Lithographic Technique) are usualy from 150 to 190 lines per inch. This is typically the maximum number of lines per inch achievable using 4 colour lithographic printing. • The method of printing onto plastics and other materials will dictate the lines per inch and cannot be summarised here. The pattern of dots remains the same no matter what the Lines Per Inch. All that changes is the scaling of the pattern so that you can achieve greater or fewer Lines Per Inch. Reduce the scaling of the pattern and you’ll achieve more Lines Per Inch. RESOLUTION :: As a rough rule, for every Line per Inch, you need 2 pixels/dots, so for a print job requiring 150lpi you need a 300dpi image. (If you are supplying Vector artwork then dpi is not an issue) *This explanation purposefully does not explain dot gain, halftone dot shapes, staccato or hexachrome printing. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 www.freelancebloke.co.uk a brief explanation *

Halftones, dots and halftone screens

Download PDF Report

Upload
others
View
5
Download
0

Embed Size (px)

Citation preview

Page 1: Halftones, dots and halftone screens

This side shows how combining Cyan, Magenta, yellow and black can give us a range of colours.

Shapes and text will look like this in the ‘artwork’ format, and only when output to print does the halftone dot and the lines per inch come into play.

This side shows how these colours are mixed using halftone dots. This simulation is how the majority of halftone printing techniques will look when inspected close up.

Each colour (cyan, magenta, yellow and black) has its own angled pattern so that the colours are able to make a regular pattern/blend together, if they didn’t have an angle to each halftone screen then each colour would simply print on top of each other giving just black.

Halftones, dots and halftone screens

When halftone printing is accurate, the 4 colours will

make a regular pattern withthe appearance of circles.

Here you can see eachscreen has it’s own angle.

1 In

Why should I care about Lines Per Inch?In the image simulation above, we can see the dots quite clearly. My horizontal black lines align to the ‘dots in a line’ on the black halftone screen, so you can count a crude 18 lines (of dots) per inch (lpi). The optimum lpi will depend on the material onto which you are printing and is generally decided by your supplier/printer unless you state it. A number of factors (ie method of printing and onto what sort of material) decide how many lines per inch are suitable or achievable. Ideally, the highest possible number of lines per inch should be used, so that the pattern of dots is not adistraction to the eye. Unlike the crude lpi above which would be suitable for the side of a Jumbo Jet.• T-shirts (printed with a Screen Print method) are usually around 50-70 Lines per inch.• A newspaper (printed using a Lithographic Technique) is printed at around 90-110 lines per inch.• Magazines (printed using a Lithographic Technique) are usualy from 150 to 190 lines per inch.

This is typically the maximum number of lines per inch achievable using 4 colour lithographic printing.• The method of printing onto plastics and other materials will dictate the lines per inch and cannot be summarised here.

The pattern of dots remains the same no matter what the Lines Per Inch. All that changes is the scaling of the pattern so that you can achieve greater or fewer Lines Per Inch. Reduce the scaling of the pattern and you’ll achieve more Lines Per Inch.

RESOLUTION :: As a rough rule, for every Line per Inch, you need 2 pixels/dots,so for a print job requiring 150lpi you need a 300dpi image.(If you are supplying Vector artwork then dpi is not an issue)

*This explanation purposefully does not explain dot gain, halftone dot shapes, staccato or hexachrome printing.

123456789101112131415161718

www.freelancebloke.co.uk a brief explanation*