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Submitting source images for print publication

Line art and everything else (non-continuous tone)


Part II — Line art and everything else (non-continuous tone)

Part I — Continuous tone images (photographs)

▲ General Introduction

These guidelines concern how to submit existing illustrations (as opposed to new illustrations produced by MetaGlyfix) for print publication in books, journals, annual reports, newsletters, etc., and usually accompanying an author’s manuscript.

[The principles herein are also useful for illustrations intended for screen viewing or web publishing, although certain submission requirements (pixel dimensions and graphic format, e.g.) are considerably less stringent for screen and web.]

Source images generally fall into one of two categories:

  1. continuous tone images — usually photographs, though sometimes certain art work, such as paintings or raster art created on a computer; continuous tone images have seemingly infinite shades of gray or colors blending into one another
  2. line art and everything else (non-continuous tone) — maps, sketches, charts, technical drawings, various genres and formats of art, clippings and graphics from previously published works, music notation, hand-written or type-written letters, photocopies, historical documents, software generated graphs, and much more

    [To determine when new drawings might be advised, see Scanning originals or drawing anew, and for details about such maps and drawings produced by MetaGlyfix, see Tips for better maps and technical drawings.]

▲ Part II — Line art and everything else (non-continuous tone)

This is a diverse category of illustrative material that includes maps, sketches, charts, technical drawings, clippings and graphics from previously published works, music notation, hand-written or type-written letters, photocopies, historical documents, software generated graphs. It also encompasses many forms of art work, including line drawings (caricatures, cartoons, etc.), prints, and paintings in various media.

The most frequently submitted illustrations in this category are black & white, more accurately called one-color because, when printed, white is the absence of ink or color, and the “black” could be any single color. When digitized, one-color illustrations are usually rasterized as 1-bit images, because the pixels are either colored or white, with no intermediary shade.

Images in this category are more accurately designated as non-continuous tone (or, briefly, “non-contone”), as distinguished from continuous tone images (i.e., photos, or “contone”), where seemingly infinite shades of gray or colors blend into one another.

For convenience, this section may refer generally to all such source illustrations by the common term “line art,” though the category is certainly broader.

An author’s line art illustrations may exist in one of the following forms:

  1. tangible — on paper or related material (which will need to be scanned, photographed, or otherwise digitized)
  2. digital scans or photographs of tangible works (thus, raster files)
  3. digital files of line art that was created on a computer or generated by software

By the end of the production workflow when files are sent to press, all illustrations, whatever their origin, will have to be in a digital format that meets the printer’s technical specifications.

When a submitted illustration requires routine touchups to improve print quality, or minor edits or revisions to better serve the author’s text, MetaGlyfix will make such improvements on the digital files during production. When available illustrations cannot be made to meet publication style requirements or the printer’s technical specifications with touchups at a reasonable cost, MetaGlyfix will so advise the client and can draw them anew.

“Line art and everything else (non-continuous tone)” encompasses a wide range of illustrative materials, and each client project, each author’s need, is unique. Unlike with photographs, there is no short list of guidelines and procedures that work for preparing and producing nearly all illustrations in this category. However, MetaGlyfix has the tools and experience to achieve what is desired by the client and required by a publisher, and the following sections should help authors and editors to prepare and submit their various forms of line art illustrations for the highest quality and most efficient production.

▲ Illustrations for reproduction with minimal changes

Most line art submitted to illustrate an author’s manuscript is intended to be reproduced as is (much like photographs) or with minimal changes.

Some source illustrations in this category may have been created digitally, but most will have been created or currently exist in a tangible medium. They might include previously printed material, such as a musical score or a page from an out of print book. Since production is all digital, line art in tangible form must be scanned or digitally photographed to convert to digital files.

▲ Tangible sources

Tangible sources must be scanned or digitally photographed to create digital files.

Best originals. Scan, photograph, or submit the best clear, clean printed or other hard copy. When mailing or shipping a tangible source, be sure to protect it as necessary. Alert MetaGlyfix if any tangible source requires extraordinary handling because of its fragility or intrinsic value.

Dimensions and scale. In most instances a tangible work should be submitted at least at its full physical dimensions. For ”dimensions” to be meaningful when a tangible work is rasterized or digitized (i.e., scanned or photographed), the digital file must also have a minimum pixel density, or resolution, measured in pixels per inch, as explained in the sections following. Scans or photographs of detailed line art produce better results when the tangible copy is larger than the final output size will be.

▲ Digital scans, digital files

Raster files. Tangible sources digitized by scanning or photography will produce raster files, which are composed of a dense grid of individual pixels that can be displayed on screen or printed. Raster files must have at least a minimum grid density, specified by publishers’ presses and printers, in order to print. The grid density is known as pixel resolution and is measured in pixels per inch (ppi).

An author’s own scans or other digital files are acceptable if they are at the correct size, resolution, format, and quality for a determined layout, as explained in Scanning resolution settings below.

Vector files. Maps, technical drawings, charts, graphs, and similar art work that is created on a computer using a vector illustration program such as Adobe Illustrator are resolution independent. They are not raster files and can therefore be enlarged or reduced any amount, presenting no quality issues at any scale.

Maps, drawings, and other illustrative art created by MetaGlyfix are always resolution independent vector files, for high-quality printing at any scale. Vector files submitted by authors should be saved as EPS files (having file extension .eps).

▲ Rasterized line art: file resolution and scan settings

As with files from digital cameras and scanned photos, rasterized line art files must be of sufficient resolution — usually measured in pixels per inch (ppi) — for the intended output method (typically an imagesetter) and printed dimensions (width and height in inches, centimeters, etc.). Unlike photos, however, rasterized line art demands a much higher file resolution in order to preserve sharpness and delineation between foreground and background.

Pixel resolution and dimensions are interrelated and can be confused. Production printers like imagesetters typically require rasterized line art files to have a resolution of 1,200 ppi at final printed size, after any straightening or cropping.

Scanning line art

If one scans a 4"-wide black-and-white drawing at a scanner setting of 1,200 ppi, straightening the resultant digital file might reduce its usable width to 3.5". Cropping out excess blank space might reduce the width to, say, 3.0". At 1,200 ppi, 3" would be its maximum width when printed. If the publication’s design calls for all illustrations to be 4" wide on the page, the 3"-wide adjusted scan would become only 900 ppi if enlarged to 4" — (1,200 ppi x 3") ÷ 4" = 900 ppi — too low a resolution for quality printing. Now, a minimum optimal scanning resolution setting that allows for straightening and cropping can be similarly calculated: (4" ÷ 3") x 1,200 ppi = 1,600 ppi. Of course, the calculation is only valid if the person doing the scanning knows exactly how much of any photo will be lost due to straightening or cropping — nearly impossible to know in advance. What to do?

MetaGlyfix can advise about optimal dimensions and scanning resolution settings for each project, and authors and editors are urged to contact MetaGlyfix as well as their publisher before preparing scans.

However, below is a Rough rule of thumb for scanning line art that will work for commonly sized books and journals:

  1. Assume an illustration to be 5 inches wide when printed.
  2. Measure the usable width of the existing line art, in inches (i.e., the width across elements of the printing or drawing, excluding borders and page margins).
  3. Divide the printed width — 5 inches — by the measured width, and multiply the quotient by 1,200 ppi; this gives the mininum scanning resolution setting.
  4. For good measure, multiply the minimum scanning resolution (of the previous step) by 1.25 for a comfortable scanning resolution setting.

Example: A drawing is on an 8.5"-wide sheet of paper, but the elements of the drawing itself span 4". The minimum scanning resolution setting is calculated as (5 ÷ 4) x 1,200 = 1,500 ppi. Multiply the minimum, 1,500 ppi, by the factor 1.25 to get 1,875 ppi, a scanning resolution setting that allows for straightening.

Note that the pixel dimensions of a digital file obtained by this rough approach — specifically, the width in pixels — is the same as specified in the Quick rule of thumb for other raster line art files, below. All non-continuous tone raster images, whatever their origin, require the same minimum resolution to be output (printed) by any particular commercial printer or imagesetter.

Other raster line art files

An author may sometimes have a raster file of line art that was directly generated by a computer application or created by a human illustrator using a computer application. It is also possible (and increasingly common nowadays) to capture a tangible piece of line art (say, an archival drawing or a page from a rare book) by a digital camera instead of using a conventional scanning machine. These, too, should have a minimum resolution of 1,200 ppi at printed size.

MetaGlyfix can advise about optimal dimensions and resolution for each project, but below is a Quick rule of thumb for other raster line art files to determine if the line art image file has sufficient resolution for printing and preserving sharpness in a typically sized book or journal:

  1. Assume the illustration to be 5 inches wide when printed.
  2. A line art raster image should be a minimum of 6,000 pixels wide (the equivalent of 5 inches at 1,200 ppi).
  3. For good measure, multiply the minimum by 1.25 (7,500 pixels wide) to allow for straightening and cropping.

All line art raster files, however created, require the same minimum resolution to be output (printed) by any particular commercial printer or imagesetter. A tangible line art document scanned according to the setting calculations described in the Rough rule of thumb for scanning line art in the previous section will have the same pixel width as minimum pixel width given just above for for other raster line art files.

▲ Exceptions

There are exceptions. Sometimes illustrations in this broad category — for example, written or printed documents — may be better treated as continuous tone. Sometimes the only available source for a line art illustration is a digital file that is less than ideal. Every case is unique, and MetaGlyfix can advise about optimal dimensions and scanning and file resolution settings for each project and illustration. And when nothing better is available, MetaGlyfix will help the author make the best of what there is, one way or another. Authors and editors are urged always to consult MetaGlyfix before submitting line art files for any project, and especially for help with essential illustrations that cannot be made to conform to the “rules.”

▲ Acceptable file formats for rasterized line art

Save and submit rasterized line art only in one of the following unaltered, native graphic file formats: TIFF or raster EPS. Because most consumer level digital cameras save captured images as JPEGs, JPEG is acceptable as long as the image has never been altered or the file re-saved. Original Photoshop or Affinity Photo files are generally acceptable as well.

[Why? JPEG is a “lossy” compression format, which means files are made smaller by the elimination of some detail in the image. Every time a JPEG is saved, more detail is lost. JPEGs are good for web publication, but not for print. GIF and PNG are also acceptable for images destined for screen and web, but generally not for print.

Some prohibitions:

▲ Author/editor preferences and restrictions

If an author or editor has any preferences or restrictions about size, placement, margins, captions, or other treatment of an illustration, please attach a note with the illustration.

▲ Custom maps, charts, and line drawings

Often there are better ways to show a scholar’s illustrative material on the printed or digital page than by scanning source material. This is especially the case if the source illustration is of poor quality, the scan needs cleaning or touching up, or the author wishes to edit or otherwise change the original. It may also be the case when an author has multiple original illustrations of varying quality and/or lacking stylistic cohesion that are intended for a single article or volume.

If the problematic original line art is not a document that needs to be presented “as is,” MetaGlyfix can create a new drawing that will better serve the author.

The two major determining factors are usually quality and efficiency. In many instances new drawings are superior in quality: they are clearer and more legible, stylistically consistent, and will output (i.e., print) better. “Efficiency” encompasses production time, overall cost, and reliability and ease of output. Authors may be surprised to learn that new drawings of problematic originals are often more economical as well. They might also consider whether the problematic illustration might be used again, perhaps repurposed in another setting, perhaps with later modifications. In such cases, new drawings might be advised.

For help in determining when to use existing line art and when to opt for a new drawing, see the guidelines Scanning originals or drawing anew? Some considerations.

(to Part I — Continuous tone images (photographs))

Last updated 24 July 2019 (Wednesday) at 04:25:11 UTC