Answer the following questions

Sheet assembly is an information-gathering point of central importance for achieving trouble-free results.

The first step in producing a sheet assembly is to draw a layout sheet containing the correct measurements. It is the same format as the sheet with an additional border and is made of dimensionally stable transparent material/paper. If we take a layout sheet for a sheet-fed offset press as an example, after positioning on the light table parallel to the axes and fastening with adhesive tape, the sheet format, gripper edge, the beginning of the print, and the center line are marked in. The data required for this are in the documentation referring to the press or may be obtained from the job itself.

The exact outlines of all of the pages to be accommodated on the top surface of the sheet must be accurately drawn, in reverse (wrong-reading). These include the distances between the pages taking into account allowances for folding and trimming. The page number must be entered in the bottom outside corner of each page.

The result of prepress – in particular error-free typesetting and its correct location on the page, the quality of the images, the registration, the quality of color reproduction on the paper, the reproduction of details and their correct location on the sheet in all color separations/colors in accordance with the original – should be checked for accuracy at the earliest possible stages in the process.

The following proofs are typical of what is used in conventional prepress:

• galley proof;

• position proof/blueprint;

• color proof;

• press proof;

Galley proofs are produced for corrections to typesetting products such as continuous text, headings and titles, headers and footers for individual pages, picture captions, footnotes, indexes, and tables of contents, as well as to control the completeness and correct location of marks and control strips. They are produced as a paper printout of typesetting files, or as a paper print or blueprint of typeset columns preset in film form or film assemblies. After checking and marking necessary corrections the originals are altered and released for the next processing steps.

Position proofs are required to check the completeness and correct location of text and image. Blueprints from the film assemblies or full-page films fulfill this purpose very well and are also cost-effective.

Color proofs are necessary for judging the quality of multicolor products. The color proof may be produced for individual images, but it is preferable to produce them for the whole page, although this is less often feasible for the whole sheet – mainly due to reasons of format.

For the printing side the color proof may be used to control the correct position of the individual color separations on the page, accurately registered assembly, the approximate overall color effect of the page or the representative color reproduction of the printed product to be produced, but with certain limitations, since the proofing process and materials used are generally not the same as the technology and materials used to produce the job; color management assists in optimizing this.

Press proofing process has the best achievable correlation with the subsequent printing of the job, especially if the printing press used is the same one that will be used to print the job. This requires a full set of printing plates. The printed proof is produced on the paper and with the ink used for the job. The effort for producing such a printed proof is considerable and only justified

for very high quality requirements. To keep high speed production machines available during the time it takes to produce the printed proofs, special proofing machines are available.