The quality of the reproductions in your book can never be better than the original material you submit to us. It is essential that the illustrative material you provide be of the best possible quality. If we judge a piece of artwork to be substandard for printing, we will ask you to provide a suitable replacement or to eliminate the image entirely.

This brief overview is intended to help you evaluate the quality of the digital art you wish to reproduce in your book. All submitted art should be accompanied by alt text; separate guidelines for alt text are available (PDF). Your illustrations need to be submitted as individual image files, not embedded in a Word document or PowerPoint. Image files should be clearly labeled following Chicago’s file-naming conventions:

• chi-Smith-fig01001.tif (for images numbered discretely by chapter)
  chi-Smith-fig0001.tif (for images numbered sequentially throughout book)

Gen AI tools must not be used to fabricate or alter the content of illustrations. This includes but is not limited to inventing or interpolating data, redrawing maps and diagrams, upsizing image files, or adding or removing elements in a photograph or other documentary image. Using AI to render visualizations of your own data, as in charts and graphs, is permitted but must be disclosed. For more, see the Press's AI guidelines.

Photographs and Tonal Images

These images, also known as raster graphics, are made up of pixels, which determine how large the image can reproduce at different resolutions, measured in dots per inch (dpi; also expressed as ppi, pixels per inch). Common examples of raster graphics are photographs, scans of original documents, or screenshots.

It is important to check the pixel dimensions of this type of image to ensure it is large enough to reproduce clearly at the final reproduction size. These dimensions are listed in the image file’s properties but are also visible when opening the file in most photo editing applications. Dividing the pixel dimensions by the required dpi will tell you how large an image can be reproduced on the printed page. For example, an image that is 1200 x 3600 pixels would print at 4 x 12” at 300 dpi, but that same image could only be 1 x 3” at 1200 dpi. A good rule of thumb is to confirm the pixel dimensions are large enough to allow the image to be at least 3” at the standard dpi, more on that below. However, we encourage you to aim above this minimum, as larger files allow the designer the greatest flexibility in sizing and would be required for any images you hope to see half or full page.

Files should be submitted in TIF rather than JPG (JPEG) format, as JPGS lose image data and quality each time they are saved. If JPG is the only file format available, do not edit or re-save the image before submitting and make a copy of the original file as a back-up.

If you need to scan an image or document, it is best to use an original. Scans of previously printed images (such as halftones from books and magazines) can result in unwanted dot pattern effects called moirés.

While editing software such as Photoshop allows users to "upsize" images to artificially add resolution to a file, this does not produce usable results and can often introduce further issues in the file. We ask that authors refrain from using this method of achieving the resolution standards above.

Continuous Tone Images

Color and grayscale images are continuous tone images, meaning they contain different colors and shades. The standard print reproduction resolution for this type of image is 300 dpi.

When submitting these graphics, check to make sure:

• The image is at least 900 pixels on its shortest side (allowing it to be 3” at 300 dpi).
• The format is TIF (preferred), JPG, or PNG.

Bitonal Images

Bitonal images contain no color or shades of gray; each pixel will be one of two values: 100% black or 100% white. Such pieces of art require higher resolution to ensure quality reproduction—the standard is 1200 dpi. When submitting these graphics, check to make sure:

• The image is at least 3600 pixels on its shortest side (allowing it to be 3” at 1200 dpi).
• The format is TIF (preferred), JPG, or PNG.

While we strongly prefer vector graphics for diagrams and charts, if you must submit that type of illustration as a bitonal image, please confirm it follows the recommendations for “Charts and Graphs” below.

Line Art and Diagrams

Vector graphics are resolution-independent and can be scaled to any size without loss of quality. They are also fully editable. This flexibility makes vectors ideal for diagrams and charts, where the legibility and editability of text and data are especially important. Most maps are also created as vector files. We recommend that you use Adobe Illustrator to create these illustrations.

When submitting vector art, check to make sure:

• You’ve used CMYK color mode (not RGB).
• The file uses standard fonts that are embedded in the file.
• The format is EPS (preferred) or PDF.

Maps

When including maps, keep textual information minimal to allow for greater readability. To ensure a map’s text or annotations remain legible and accurate, it is strongly recommended that all maps be prepared by a professional cartographer for design consistency. If needed, your editor can help locate a cartographer or provide map layout examples by trim size.

Important things to consider in map creation:

• Use as few typefaces and font styles as possible.
• When color is used to convey information, it must be easily distinguished from other colors on the map.
• Labels should have sufficient contrast from background colors for legibility.
• If a map will run across a spread, critical information must not appear in the gutter.
• Line weights should be at least .3pt.
• Use patterns rather than shades of black or color when possible.

Charts and Graphs

Charts and graphs can be used to display data visually. Because these are usually printed at sizes ranging from 3 x 3” to 4 x 7”, it is important to take certain design factors into consideration for legibility on the page.

• One consistent line weight is preferred, but widths less than 0.5 (one-half) should not be used.
• Use one font point size throughout the figure. If two sizes are used, they should vary from each other only slightly (e.g., 10 pt and 12 pt, not 10 pt and 18 pt).
• Font styles should be used sparingly. In most cases, there is no reason to use bold or italic.
• Do not use all caps, as this decreases overall legibility.
• Use tints (gray tones) sparingly. Use solid black and white where possible. Tint variations that are not easily distinguishable from each other may confuse the reader. Use 20%, 50%, and 80% tint values.
• If data on a graph or chart needs to be distinguished with more variation than solid black and solid white allow, then patterns should be used.