The Offset Process of Book Printing
The offset process of book printing is a very complex procedure. It typically involves the use of chemicals, equipment and ink that are layered onto a piece of paper and then pressed into the surface by a combination of pressure and heat. The resulting ‘negative’ image can be used for making reproductions in any size or color.
The offset process is heavily automated as modern presses are so fast and precise that it would be impossible to do this manually. Printers use negatives to make accurate reproductions which they print on sheets or paperback books using ink, paper, water and glue — all materials found in nature. The offset process divides the printing into 4 stages which are:
- Making the plates, or printing masters: A camera, film or computer scans a document and turns it into a negative image. The negative is then chemically treated to make it resistant to ink and then etched onto a plate of aluminum or other metal. Printing presses can be equipped with several plates where each plate applies ink to a different color of paper. Metal plates are very durable and require little maintenance over their life.
- Inking: A roller transfers ink to the plate in a precise manner that matches the outline of the image on the plate, this is called "registration.” Inks are mixed together according to their colors and each color has a different image on each of the plates inks. A roller is generally used to transfer the ink from the plate to a sheet of paper.
- Printing: The image is transferred onto the sheet by pressing a roll of paper against it with great pressure and heat. This lifts the ink to create a layer of ink on top of paper that is thinner than a human hair—this layered ink makes up about 20%–30% of each printed page. To allow for perspective, images are often printed twice, once in long edge (or "landscape") format and then in portrait format.
- Binding: The paper is then cut into books and either placed in a machine that repeats the printing on the inside and joins them together or put into a binding machine where glue is applied to create a hard cover. There are many different methods of binding, including sewing, sewing-stitching, comb binding and wire-stitching.
The offset process can be performed by varying the pressure of the rollers so that "the ink can flow from the printing plate to your page". Inks are water based with gels. Warming them during application helps them spread and dry more evenly, improving quality.
Since the ink is applied to paper to create a "negative" image, this means that the image is made on both sides of the paper. The photos in this article are not printed on both sides; therefore, some of them might be hard to read.
Though the offset printing process doesn't produce what we call a "binding" yet it does create something else…the book! The printing process itself has made it possible for us to make many books at one time, even millions of copies. Books are said to be 300 years old but we have actually been printing books for only about 200 years or so.
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Title: Printing a Photograph in a Unix-like Operating System - Linux and Unix
What is the process of printing a photograph in a Unix-like operating system? The same as any other file format, the print command in UNIX will let you print the actual file directly. On Linux systems, it is done using xdg-open command. This guide will describe how to take up an image file and print it on the local system or on remote systems over FTP.
One common reason for printing of photos is children are wanted to be able to carry them around with them – what better way than in the form of hardcopy. Another reason could be that the picture is an important record of a special event – like a wedding. Choosing the appropriate photo printing software to do this may take some time as there are many to choose from.
In case of Linux or Unix based operating systems, the print command will allow you to print one file or set of files. It can be used with either the file name or a filename specified in the argument. Printing files by simply specifying their name will bring up a file selection dialog box where you can select files and edit them before actually printing them.
Alternatively, you might use xdg-open command which has been ported for use on Linux and Unix systems. This command will allow you to open any directory and files on such systems. It is a part of the freedesktop.org project and works on both Linux distributions (including Debian) and Unix based operating systems. This includes Solaris and IRIX too.
The xdg-open Project
xdg-open which stands for the XDG standard for opening files or locations will allow you to open the folder where the file is located and display it in an appropriate application that can be used to edit it or print it out. This is pretty handy as you don't have to worry about where the file is located or if there exists an appropriate application for editing of printing of that particular image type.
The command should be used as follows:
$ xdg-open file.jpg
This will open the file in a medium size terminal window which allows you to edit and print it as it is if needed. The following screenshot shows how this would look:
This is also a great way of using the same image on many different systems. For example, in case you need to print an image during a presentation at work, you can just save the same file with different name on the local system and use this method to print it out.
Another use of this command is to open a file in the standard image viewer for the system.
Printing a Photograph with xdg-open
Once the file has been saved or opened using xdg-open command, it can be printed using a command like below:
The print command is used with either the filename or file argument in Linux, while on Unix based systems like Solaris and IRIX, you would use xdg-open as shown below:
An example of this is shown below:
This is a method of printing that not just includes one photo but many, even millions. And this is done by simply specifying all the files you want to print in one go. This can be done with either xdg-open or print command.
Printing a Set of Photos Using xdg-open
Another way of printing photographs is by specifying the same image on different systems or different computers with the same name. For example, if you want to print an image named "family portrait" on two different systems, you can do so by simply specifying both filenames as shown below:
This will create a file called family portrait1.jpg and family portrait2.jpg in the user's home directory which are both in PNG format and contain the same image but in different formats.
Conclusion
In this article, we have discussed the printing of photographs in UNIX based operating systems such as Linux, Unix and IRIX. The same methods can be used to print images from Windows, Mac OS X and some BSD-based systems as well.
In the next article in this series, a tutorial will be provided on how to convert photos from one format/type to another like JPEG or PNG format.