Inside this issue
Book Print Quality
A Look at Lithographic Screening
Amateur Photographer who plays with big cameras and film when in between digital photographs.
We’ve included Dav Thomas’ book in this issue and one of our comments about it was how good we thought the print quality was. What do we actually mean by this? Well there are various aspects that make up the quality of printing in a book but one of the biggest influences is the way that the photographs are converted into plates for the lithographic print process.
We’ve all seen newspaper print, especially black and white newspapers, where you can see the individual dots that make up the picture. These output like this is referred to as ‘halftone’ because it can produce fractions of the ink color. This ‘halftone’ is used because newspaper ink is either black or white and there are no cost effective processes for diluting the colour to create ‘continuous tone’ prints.
The pattern usually used in halftone printing is a grid of dots, usually slanted at some angle. The image below shows an example of mono newsprint halftone.
As well as being referred to as halftones, the technique is also known as ‘screening’ because William Fox Talbot’s proposed process was based on photographic ‘screens’ referring back to the Chinese method of printing with silk screens.
A screen is then the pattern that is produced from a continuous tone original. This pattern is then typically etched into a metal plate which is then used to print the final product.