3.2. F2 IMPOSITION PARAMETERS panel

3.2. F2 IMPOSITION PARAMETERS panel

This panel is used to select the most important imposition parameter – the type of binding. The choice of binding type determines the algorithms used to distribute the imposed pages onto sheets. The available options are: perfect binding, saddle stitch binding, and sewn binding. The Impozycjoner B software is used to impose books or brochures whose content consists of signatures. A signature is a set of printed sheets of paper folded (folded, creased) once or several times. A signature can consist of one sheet (single-sheet signature) or several sheets (multi-sheet signature). The smallest element of a signature is a 4-page, i.e. a set of 4 pages lying at equal distances from the center of the signature, which is why the program does not allow the imposition of pages whose number is not divisible by 4 without a remainder.

A book block is a set of signatures which, when combined with a cover, forms a book or booklet. A book block can be multi-signature (sewn or perfect binding) or single-signature (saddle stitch binding, all sheets are merged into one signature, usually sewn with wire). If the book block is multi-signature, perfect binding is possible if the signatures are single-sheet.

Number of pages per sheet

Another parameter to be set in this panel is the number of pages per imposition sheet (4, 8, 12, 16, 24, and 32).

The number of pages that can be placed on an imposition sheet depends on the format of the sheet itself and the size of the pages to be imposed. For example, you can fit 4 pages of an A3 document, 8 pages of an A4 document, and 16 pages of an A5 document on a sheet similar to A2 (e.g. A2++).

Turning the sheet over to the other side

It is assumed that the imposition sheet is a sheet with horizontal orientation (width is greater than height). After the one side is printed, the sheet can be turned over to the other side by the side guide (in other words, by the shorter edge) or the front guide (i.e. by the longer edge).

The choice of how to turn the sheet over to the other side is important for the algorithms that arrange PDF pages on the sheet. Pages laid out for turning by the side guide cannot be printed on a sheet turned by the front guide.

Folding scheme

Each sheet of paper can be folded in at least several ways. Each folding method is described by a folding scheme, and the selection is made from a drop-down list. The more pages on a sheet, the more folding options are available.

The list of folding schemes is reset and rebuilt each time the user changes the number of pages on the sheet.

All folding schemes are constructed in such a way that the 4-page fold with the number 1 is located at the right edge of the sheet. You can change the edge to the left by selecting the Rotate the folding scheme 180° option.

The items in the folding scheme list consist of the name and definition of the folding scheme separated by the " • " characters.

The name is not saved in projects or schemes and can be changed at any time without any restrictions. The scheme name can be changed by editing the Comment element in the XML file with the diagram definition (folder MyImpozycjoner\Settings\v5\B_XML\FS). The list of diagrams is sorted, so by choosing appropriate scheme names, you can adjust the order of schemes in the list.

The folding scheme designation consists of (the folding scheme designation is also the name of the file with its definition):

• from the sequence before the dash used to indicate the orientation of the page for which the folding scheme is intended: P – for vertical (Portrait), L – for horizontal (Landscape), PL – indicates a square page. After indicating the orientation, a two-digit number is added to indicate the number of pages per sheet for which the scheme is intended.
• the folding scheme marked with a sequence of three-character phrases separated by a dash. The number of phrases is equal to the number of folds. A phrase consists of a digit and two letters. The digit indicates the folding position (2 – in the middle, 3 – in one third). The first letter indicates which part of the sheet is folded (R – right, L – left, T – top, B – bottom), the second letter indicates the direction of the fold (U – under the remaining part of the sheet, O – over the remaining part of the sheet).
• the designation whether the whole sheet will be cut into smaller sheets before folding, which is specified in the last sequence of the scheme definition. If the sheet is folded without cutting, the sequence is NC (Not Cut). If the sheet is cut, the phrase consists of the letter C, the number of parts after cutting and the number of pages, for example C2x4 (sheet cut into 2 parts with 4 pages each). The character x (lowercase) means that the cut is parallel to the shorter edge of the sheet, the character X (uppercase) means that the cut is along the longer edge of the sheet.

Example 1

Folding scheme 2LU-2TU-2LU for an 16-page sheet and portrait page orientation

Step 1 (2LU): fold the sheet into 2 parts, left side under neath [1]

Step 2 (2TU): fold the sheet into 2 parts, top side under neath [2]

Step 3 (2LU): fold the sheet into 2 parts, left side under neath [3]

Example 2

Folding scheme 2TU-2LU for an 8-page sheet and the landscape orientation of the cell grid:

Step 1 (2TU): fold the sheet into 2 parts, top part goes under neath [1]

Step 2 (2LU): fold the sheet into 2 parts, left part goes under neath [2]

Bleed

The next parameter is to set the bleed size. The bleed size specified in the panel is its maximum size. The bleed size between the grid cells is determined by adjusting the spacing between columns/rows. The bleed (if present on the PDF page) will be cut to half this distance. The bleed will be cut to the maximum value specified when the distance between columns/rows is greater than or equal to twice the bleed value. The bleed will also be cut to the maximum value at the outer edges of the imposition.

Example. Grid cell parameters: bleed = 3 mm, distance between columns = 6 mm, distance between rows = 6 mm, trim-off = 1 mm.

In perfect binding, you can additionally set the trim-off margin (inner bleed).

Number of pages in complete signature

In the F2 IMPOSITION PARAMETERS panel, you can also set the number of pages in a signature (applies to sewn binding). The number of pages in a signature must be divisible by 4 without remainder.

A signature with the declared number of pages is called a complete signature, a signature with fewer pages than declared is called an incomplete signature, and a signature with more pages than declared is called an overcomplete signature.

If the number of pages in a book (e.g. 160) is divisible by the number of pages in a signature (e.g. 16) without remainder, all signatures in the book (10) are complete. This situation is rare. Most often, the number of pages in a book cannot be divided by the number of pages in a signature without a remainder, and a signature with fewer pages than declared must be made (e.g. 168/16=10 remainder 8, i.e. the book consists of 10 complete 16-page signatures and one uncompleted 8-page signature).

Signatures are made up of sheets. The number and type of sheets needed to create complete signatures should be determined in a similar way to calculating signatures in a book block.

The declared number of pages in the signature is divided by the number of pages per sheet, thus obtaining the number of whole sheets necessary to print the signature. The remainder of the division is used to calculate the number and type of split sheets needed to print the signature.

A full sheet is a sheet on which each page of the imposition file is different. An split sheet is folded after being cut into smaller parts, which sometimes means a change in the direction of the paper fibers in such a sheet.

Example 1

The book is to consist of 176 pages, which is correct, as 176 is evenly split by 4. The number of pages in a signature should be equal to 32. Dividing 176 by 32, we get 5 with a remainder of 16, which means that the book will consist of 5 complete 32-page signatures and one incomplete 16-page signature. If we use 8-page sheets, we will need 4 whole sheets to print one complete signature (32/8=4). To print the incomplete signature, we will need 2 whole sheets (16/8=2). In total, 22 sheets are needed to print the entire book (5*4+2).

Example 2

The same book as in example 1 (176 pages, 32 pages per signature), this time using 16-page sheets. To print one complete signature, we will need 2 whole sheets (32/16=2). To print an incomplete signature one whole sheet (16/16=1) is needed. In total, 11 sheets are needed to print the entire book (5*2+1).

Example 3

The example is similar to the first one, but this time the book is to consist of 180 pages. The number of pages in a signature is to be 32. Dividing 180 by 32, we get 5 with a remainder of 20, which means that the book will consist of 5 complete 32-page signatures and one incomplete 20-page signature. If we use 8-page sheets, we will need 4 whole sheets to print one complete signature (32/8=4). To print an incomplete signature, we need 2 whole sheets (16/8=2), but there are 4 pages left that are not included in the whole sheets (20-16=4). These 4 pages will be arranged on an 8-page sheet and therefore must be duplicated twice.

When using 16-page sheets, 4 pages will be duplicated 4 times on such a sheet (4 x 4 = 16).

Example 4

An example similar to the second one. This time, the book is to consist of 188 pages. The number of pages in a signature is to be equal to 32. Dividing 188 by 32, we get 5 with a remainder of 28, which means that the book will consist of 5 complete 32-page signatures and one incomplete 28-page signature. If we use 16-page sheets, we will need 2 whole sheets to print one complete signature (32/16=2). To print the incomplete signature, 1 whole sheet (28/16=1 with a remainder of 12) is needed, but there are 12 pages left that are not included in the whole sheets. These 12 pages will be arranged on two incomplete sheets: 8 pages will be duplicated twice on the first split sheet, and 4 pages will be duplicated four times on the second split sheet. In total, we will use 3 sheets (one complete and two split) to print an incomplete signature!

It is worth noting here that printing 28 pages in an incomplete signature (3 sheets: 16 + 8 + 4) may involve a higher cost than printing 32 pages (only 2 sheets). It is important to maintain a balance between the price of the plate, paper and print run.

This means that it is possible to print a complete set of pages in a signature using split sheets (declaring a 20-page signature with a 16-page sheet immediately requires the use of a whole sheet and a split sheet for each signature).

However, the number of sheets in a signature is usually a multiple of the number of pages per sheet.

List of split sheets

Sheets in the signature table are marked with a letter and a phrase indicating how many times the document is duplicated on the sheet.

Whole sheets are marked with the letter W (from Whole) and a phrase starting with 1 and a multiplier indicating the number of pages on the sheet:

• W1x4 – whole 4-page sheet;
• W1x8 – whole 8-page sheet;
• W1x12 – whole 12-page sheet;
• W1x16 – whole 16-page sheet;
• W1x24 – whole 24-page sheet;
• W1x32 – whole 32-page sheet.

Split sheets may be marked with S (for Split) and B, A or O (for form-to-form split sheets).

A split S sheet is the same as a non-full sheet Impozycjoner A program.

A PDF file with a N sheet type is a single-sided file. Both sides of the paper sheet are printed with the same single page of the PDF file. Folding takes place after the sheet is cut into two parts. Using such sheets in imposition reduces the printing cost, as one less set of offset plates is needed. The disadvantage is that in some cases such a sheet must be turned over to the other side by a different edge than whole sheets, which can be a significant inconvenience.

The program notifes you about this situation by displaying an appropriate warning.

If changing guides is a problem, the solution is to use incomplete sheets of the form-to-form type. Sheets of this type are always double-sided and there is no problem with changing the way the sheet is turned over to the other side.

The type of split sheets used in imposition is selected by setting the Use split "form to form" sheets option.

For split sheets of the form to form type, it is possible to make at least several page arrangement. In the Impozycjoner program, the user can define, select and use one of three arrangement. Sheets of the form to form type can be marked: B – for the basic defined arrangement, A – for the alternative arrangement or O – for the third layout. Installation arrangements for sheets marked with the letter O occupy only part of the sheet and are intended to be used in the Impozycjoner A version of the software to add other jobs to them.

It is also possible to change the form to form sheet type for a selected single sheet using the context menu that appears when you select that row and press the right mouse button. However, this change is not permanent (like other changes made using this menu) and will be overwritten each time the sheet table is recalculated.

With 4 pages per sheet, split sheets do not occur because there are no sheets with fewer than 4 pages in the document.

Types of split sheets:

For 8 pages per sheet:

For 12 pages per sheet:

For 16 pages per sheet:

For 24 pages per sheet:

For 32 pages per sheet:

Depending on the number of pages in an incomplete signature, a signature may consist only of whole sheets, a combination of whole and split sheets, or split sheets alone. It is worth noting that sometimes the cost of printing such a signature may be higher than that of a complete signature, even though it contains fewer pages. For example, to print a 28-page signature on 32-page sheets, three sheets must be used (W2x16 + S4x8 + S8x4).

Example. For a 24-page signature and an incomplete signature consisting of 20 pages, it is necessary to use as many as 5 split B3x4 sheets to print such a signature (20/4=5). Each of these sheets has a print run 3 times lower than the whole W1x24 sheet.

In 12- and 24-page sheets, split sheets (S3x4) are cut into individual 4-page sections, which can sometimes cause problems when sewing such sheets into signatures. Therefore, when imposing books with whole 12-page sheets, it may be better to make pages from incomplete signatures using a different imposition, e.g. with 8-page sheets.

The F2 IMPOSITION PARAMETERS panel also includes an option to set the value of the so-called trim-off (also known as internal bleed), which applies only to perfect binding.