Managing Digital Raster Resolution For Print

Terms

PPI – Pixels per inch

DPI – Dots per inch

LPI – Lines per inch

Bit Depth – The number of bits used to define each pixel

Definitions

PPI "pixels per inch" is the number of pixels per line per inch in a digital image. Image size is determined by establishing a horizontal and a vertical value for an image. For example, the display size on the monitor I am using is currently set to 1920 x 1080. The file size for a color image is determined by multiplying the horizontal and vertical pixel dimensions, then multiplying by the “bit depth”, then dividing that number by the minimum color bit standard of 8. Below is an extreme magnification showing individual pixels.

Pixel magnification at 1600%

DPI is the number of “printed” dots of ink per line per inch. DPI is the resolution of a printed illustration and is referred to as "dots per inch". Some sources consider PPI and DPI to be interchangeable. However, since PPI exists in a digital environment and DPI does not, I prefer to refer to them separately. A higher the DPI results in an image with greater detail provided the PPI of the original file is of an equivalent higher resolution.

LPI is used by printers and publishers in their production specifications when they convert continuous tone or digital images for commercial printing. Commonly referred to as “line screen”, halftones and color separations are classified using LPI. For instance, The Wall Street Journal prints images using a 100-line screen. Travel & Leisure Magazine is printed at 133lpi or uses a 133-line screen. Although printed images appear to the naked eye to have continuous smooth tones, they are made up of finite dots and spaces, which become visible under magnification. See below.

CMYK screen pattern magnification.

Halftone screen pattern magnification.

Bit Depth is the number of “bits” used to define a pixel. The number of bits per pixel determines the number of grey scale or color tones that can be represented in an image. A 1 bit per pixel image has two tones, black or white (2 to the power of 1). An 8 bit per pixel image has 256 tones (2 to the power of 8), and a 24 bit per pixel image contains 16.7 million tones (2 to the power of 24).

Managing Resolution

So how can you be sure that you’ve created your illustration at the proper resolution? Here are three simple principles to always keep in mind.

Principle #1 Think Ahead. 

Always check the production specifications for any publication, printer, website, or output device before you assign a size or resolution to a new document. 

Additionally, try to anticipate all possibilities you may want to use your illustration for in the future. For instance, you may want to use a web image you created at 72ppi for an 800 x 600 display space in an offset printed promotion that requires a 400ppi at 100% file. Many sources provide blanket recommendations for file size, such as “always use 300ppi at 100%”, but this could turn out to be insufficient. This brings up another rule of thumb.

Principle #2 Think Large.

Digital file size can be very changeable as long as the only way you change a files size is down, or make the file smaller. 

Changing a files size is referred to as “resampling” and artists, designers, printers, etc. all resample to comply with display and production specifications for publishing images. It’s important to understand the distinction between resampling and “resizing”. Resampling is changing the number of pixels in an image i.e., the file size. Resizing is changing the size an image will print without changing the file size/number of pixels.

Original image: 3" x 4" at 300ppi, or 3.09M.

Resized image: 9" x 12" at 100ppi, still 3.09M.

When you decide to resample an image down or reduce its size, programs such as Adobe Photoshop, discard data to reduce the file. This works because the data that was discarded was there in the first place. And unless you retain an original version of your file, the data that is discarded is permanently gone. Now, to increase the size of a file, you have to add data to it, but there isn’t any true data to add, so the software program will fabricate the missing data. This nearly always results in a visually perceivable quality loss.

Resampled image: 3" x 4" at 200ppi, now 1.37M.

Principle #3 Think Twice.

The rule of thumb when converting PPI’s to DPI’s or LPI’s is to think two to one. In other words, a publication using 150dpi or line screen will require a digital file that is at least 300ppi at 100% of the image dimensions. This applies when creating a file that will be converted to a color separation and printed on a commercial printing press.

Also, don’t forget Principle #1. I recently ran across a magazine that used a 150-line screen for images but required all files to be 600ppi at 100%. So if a file was created at the ratio of two to one, there was a chance it would be rejected by the publication. And remember Principle #2; “sampling up” would not be an option.

Halftones, Duotones, and Tritones

The resolution needed for halftone, duotone, and tritone printing varies from the resolution needed for a CMYK continuous-tone or “contone” image. Here’s a way to understand why. Consider that a contone image at 300ppi is made up of a 300ppi cyan channel, a 300ppi yellow channel, a 300ppi magenta channel, and a 300ppi black channel. So in essence, for an image setter, the 4-color image channels will combine to have 1200ppi in total. Since a halftone is a monotone image, and a duotone or tritone is a combination tone image, they contain less than four channels. So they have less density and require a higher resolution to make up for it. Here are recommendations for file resolutions.

Halftone (Monochrome)

1200ppi at 100% image size. (1200ppi x 1 color = 300ppi x 4 colors)

Halftone image.

Duotone (Two Color)

600ppi at 100% image size. (600ppi x 2 colors = 300ppi x 4 colors)

Duotone image.

Duotone swatches.

Tritone (Three Color)

400ppi at 100% image size (400ppi x 3 colors = 300ppi x 4 colors)

Tritone image.

Tritone swatches.

Laser and Inkjet Output 

Photo-quality ink jet printers use DPI resolution for classification purposes. Most printers print in thousands of dots per inch. 1200 to 4800dpi printers are typical. Good quality image prints can be achieved with files that have 140-200ppi resolutions at 100%, and high quality image prints are possible with 200-300ppi resolution files. Laser printers are generally thought to be higher resolution than inkjet printers.

Digital Art & Copyright Law

There are many misconceptions concerning the use and effects incurred by copyright law. “Copyright Law of the United States”, published by the US government is 351 pages long. Although much of the information doesn’t pertain to visual artists, that which does, is absolute, so it pays to know how copyright effects what we do as illustrators for our livelihood. Whether work is created digitally or traditionally the same laws apply. 

© 1995 Don Arday.

Copyrightable Art

All art is copyrighted from the moment it is produced or becomes a fixed copy. Copyright means the right to copy. “Copyright protection subsists … in original works of authorship fixed in any tangible medium of expression.” In the case of digital art, the display of a work on a monitor through a digital transmission constitutes the establishment of a copy. “A work is 'created' when it is fixed in a copy.” 

Notice of Copyright

Before April of 1989, copyrighted art had to be accompanied by a copyright notice. The word “copyright” or the familiar “©” symbol had to be displayed with the artwork. At the present, all art is copyright protected whether it contains the symbol or not.

Now that said, use of the word or symbol is recommended. The use of it serves as a warning to possible copyright infringers, in this way, it can authenticate and strengthen the protection of your artwork.

The copyright symbol is available on keyboards by the keystroke <option g> or <alt g>. It is also available through the Object Palette in many software programs. The correct form is: Copyright: Date(s): Author/Creator/Owner. The word “copyright, the symbol ©, or the abbreviation “copr” may be used.

Original Work

A “work of visual art” is a painting, drawing, print or sculpture, existing in a single copy, in a limited edition of 200 copies or fewer that are signed and consecutively numbered by the author, or, in the case of a sculpture, in multiple cast, carved, or fabricated sculptures of 200 or fewer that are consecutively numbered by the author and bear the signature or other identifying mark of the author. 

For digital artists this still applies. A digital painting or drawing illustration created in Adobe Photoshop, Corel Painter, or any other image-based software, is considered a “painting”. Digital drawings created in Adobe Illustrator, Corel Draw, etc., i.e. vector illustrations are “drawings”.

Copyright Law

Copyright law in small doses falls into the category of “civil law”, meaning that your legal rights as the artist would have to be implemented though the initiation of a law suit. However, large violations involving 10 or more copies with a value of over $2500 is a felony, which falls into the category of “criminal law”. In the case of all art, to display a work publicly means to transmit it.

Derivative Work

The derivative work concept is perhaps the most misunderstood part of copyright law. The derivative work clause regulates the use of copyrighted reference material. For some illustrators this can have a great impact on the use of reference material. Copyright law supports the making of derivative works, but only by, or through the permission, of the copyright owner.

A “derivative work” is a work based upon one or more preexisting works, such as a translation, musical arrangement, dramatization, fictionalization, motion picture version, sound recording, art reproduction, abridgment, condensation, or any other form in which a work may be recast, transformed, or adapted. A work consisting of editorial revisions, annotations, elaborations, or other modifications, which, as a whole, represent an original work of authorship, is a “derivative work”.

It is highly advisable to exercise caution when using published work as a reference source. As alluded to in copyright law, every photograph, artwork, artifact, etc. is copyright protected.  And through the internet, gathering reference copies of images has never been easier.

Fan Art

Fan art is a form of derivative art. It is when another artist uses original characters or settings created by the originating artist. For instance, when an illustrator uses Spiderman as a straightforward character in a promotional illustration. This kind of use requires the permission of Marvel Comics. However the parodying or making fun of a copyrighted character or situation does not require permission of the copyright owner. This falls into the category of “fair use”, but it doesn’t necessarily mean you won’t end up in court. 

This is important to know. Fan art using settings and characters from a previously created work could be considered a derivative work, which means the copyright would be owned by the character/settings originator. So, if I did an illustration of Spiderman, I would not own the copyright of my own work! And, any display of my fan art Spiderman would be an unlawful distribution of a derivative work.

Fair Use

Fair use is the use of a copyrighted work, for purposes such as criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research. If the reason for use of a copyrighted work falls under this description it is not an infringement of copyright. However, the following factors go into determining whether the use would be considered fair use: The purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit educational purposes; the nature of the copyrighted work; the amount and substantiality of the portion used in relation to the copyrighted work as a whole; and the effect of the use upon the potential market for or value of the copyrighted work. The fact that a work is unpublished shall not itself bar a finding of fair use if such finding is made upon consideration of all the above factors.

Work Made for Hire

A “work made for hire” is a work prepared by an employee within the scope of his or her employment; or a work specially ordered or commissioned for use as a contribution to a collective work; such as a movie, audiovisual work, a supplementary work, a compilation, an instructional text, test or answer material, or an atlas. 

A “supplementary work” is a work commissioned for publication to support the work of another author. Illustrations commonly fall into the category of supplemental work. Examples of supplementary works by illustrators would be non-self authored commercial editorial illustrations, commercial book illustrations, corporate illustrations, etc. Nearly every commission could conceivably be a work made for hire, but only if agreed upon by the illustrator and the commissioning party. All parties must expressly agree in writing to the “work made for hire” designation. 

Watch out. It is vitally important to consider the following: If a work is "made for hire", the employer, not the illustrator artist, is considered the legal author and owner of the copyright for the work. Many publishing houses and magazine conglomerates are adopting and enforcing “work made for hire” contracts. This may sound absurd, but bound by one of these “work made for hire” contracts, the original illustrator would have to get permission from the contractor to display or publish the illustration. 

VARA

VARA also known as “The Visual Artists Rights Act of 1990 or Statute 106, exclusive rights in copyrighted works. VARA protects the “moral rights” of the artist as it relates to his or her creation. Only “works of visual art”, a painting, drawing, print or sculpture, existing in a single copy, or in a limited edition of 200 copies or fewer qualify for VARA benefits. VARA gives the artist creator the exclusive rights to do or authorize the following:

Concerning the Work (Statute 106)

The right to reproduce the copyrighted work in copies; to prepare derivative works based upon the copyrighted work; to distribute copies the copyrighted work to the public by sale or other transfer of ownership, or by rental, lease, or lending; and in the case of pictorial, graphic, or sculptural works, to display the copyrighted work publicly.

Concerning the Creator (Statute 106A)

Titled the “rights of attribution and integrity”. The right to claim authorship of a work; to prevent the use of one's name on any work the author did not create; to prevent use of one's name on any work that has been distorted, mutilated, or modified in a way that would be prejudicial to the author's honor or reputation, and to prevent distortion, mutilation, or modification that would prejudice the author's honor or reputation. Authors of works with "recognized stature" may prohibit the work from being destroyed. These rights persist for the life of the author. 

Copyright Registration

Copyright registration serves to verify the ownership and date of creation of a work of art with the authority of the United States Copyright Office. Registration of a work does not constitute a “granting of copyright”. Copyright is automatically granted when the work created and displayed. However, copyright registration establishes a public record and adds proof of copyright ownership to aid in fighting copyright infringement.

The US Copyright Office provides standardized forms. The web locations are linked below. The basic registration fee is ($65) for a single work or a group of works. Two or more individual works can be registered on one application with a single filing fee under certain circumstances, see below. Electronic filings made online through the Electronic Copyright Office or “eCO” are available at a reduced fee for ($35).

A group of unpublished works can be registered as a collection if all the elements of the collection are assembled in an orderly form, the combined elements bear a single title identifying the collection as a whole, the copyright claimant for each element in the collection are the same, and all the elements are by the same author or, if they are by different authors, at least one author has contributed copyrightable authorship to each element. All of these conditions must be met and works registered as an “unpublished collection” will be listed in the records of the Copyright Office only under the collection title.

For published works, all copyrightable elements that are included in a single unit of publication and in which the copyright claimant is the same can be considered a single work for registration purposes. An example would be a children’s book with multiple illustrations.

Sources and Resources

US Copyright Office Website

http://www.copyright.gov/

Single Visual Arts Copyright Registration Form VA

http://www.copyright.gov/forms/formva.pdf

Single Visual Arts Copyright Registration Short Form VAS

http://www.copyright.gov/forms/formvas.pdf

Group Visual Arts Copyright Registration Form GRVA

http://www.copyright.gov/forms/formgr_va.pdf

Electronic Copyright Office System

http://www.copyright.gov/eco/

Copyright registration for Works of the Visual Arts

http://www.copyright.gov/circs/circ40.pdf

Copyright Office Fees

http://www.copyright.gov/circs/circ04.pdf


The information in this post is provided for educational purposes only. It is not intended to replace or substitute for professional legal advice.

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© 2016 Don Arday.

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