Digital Art Guidelines

• Check figure resolution: All figures must meet our resolution requirements (see “Resolution Requirements for Digital Art” on page 2).
• Save figures: Save each image as a separate file.
• Name files: File names should include chapter and figure numbers; for example, fig. 14.1 should contain “14.1” as part of the file name.
• Add callouts: Indicate location in the text with caption or bracketed callout (e.g., [Fig. 14.1]) between paragraphs; do not embed images in text.

• File format: We prefer EPS or TIF files. Other formats—such as GIF, PNG, or BMP—are often problematic or unusable. JPEG files are often usable but can easily be degraded (see“JPEGs” below).
• Word files: Do not embed figures in your Word files.
• Online images: The way an image looks on a computer screen is not an indication of its quality, and these images rarely meet the resolution requirements for reproduction (see  “Internet Images and Screen Captures.”
• Increasing resolution: Adjusting the resolution or dimensions of a substandard file will not improve its quality (see “Adjusting Resolution and Dimensions”).
• Color images: We often use color images in our ebooks, so do not convert color images to grayscale. We will make the conversions necessary for the print edition.
• PowerPoint files: These are usually inadequate for reproduction, so check with your editor if you cannot provide them in another format.

Each time a JPEG is opened and re-saved, the quality degrades. If you need to rename a JPEG,right-click on the file and select “Rename” from your menu options—rather than opening the file and re-saving it under a new name—to avoid degrading the image. If you receive an image from an outside source, request a TIFF format. If JPEGs are the only file format available, do not edit or re-save the image, and please make a copy of the original file as a backup.

Most images on the web are sized for computer display and are therefore not acceptable for print publication. If you plan to use an image from the web, we recommend that you include a URL with your art submission so that we have access to the original image. Please see the “Resolution Requirements for Digital Art” section (below) for more information.

Digital art renders images as a finite number of dots called pixels. The reproduction size of a given image is therefore limited to the number of pixels—measured in pixels per inch, or ppi—in the file. Be sure your files meet these requirements:

• Color and grayscale images, such as photographs, must be at least 300 ppi.
• Line art, such as maps or drawings, must be at least 1200 ppi.

Your images must be scanned at the correct resolution and at the correct size to avoid jagged curves and blurry, pixelated photos.

Color and Grayscale Images

In color and grayscale images, each pixel can vary in color and tonality, making transitions from light to dark smooth and realistic if the resolution is high enough. To ensure a quality reproduction of a color or grayscale image, the file must have resolution of at least 300 ppi at the final printed size, whether printed as a grayscale or color image. For example, a color or grayscale image with dimensions of 900 × 1500 pixels can be reproduced no larger than 3 × 5 inches. For the best results, we would like image files to be 5 × 7 inches at 400 ppi (or 2000 × 2800 pixels).

Line Art

In line art, each pixel has only one of two values: 100% black or 100% white. These images require higher resolution—1200 ppi—to ensure quality reproduction.For example, a line-art scan with dimensions of 3600 × 6000 pixels can be reproduced no larger than 3 × 5 inches. For the best results, we would like image files to be 5 × 7 inches at 1200 ppi (or 6000 × 8400 pixels).

On a PC

1. Open Windows Explorer and locate the image file(s).
2. Right-click on the file and select “Properties” from the drop-down menu.
3. Click the “Summary” tab at the top of the dialog box.
4. Click the “Advanced” button in the summary window.
5. The summary will now display the width and height of the file in pixels.
6. Using these pixel dimensions, calculate the maximum reproduction size of the file by dividing the number of pixels by the ppi required. For example, if a color or grayscale image file’s dimensions are 590 × 387, this image can be reproduced as an image measuring 1.9 × 1.3 inches or smaller (590 ÷ 300 = 1.9 and 387 ÷ 300 = 1.3).

On a Mac

1. Open Finder and locate the image file(s).
2. Right-click on the file—or press the “Control” key and click on the file—and select “Get Info” from the drop-down menu.
3. The dimensions of the file are listed under the “More Info” section of the dialog box.
4. Using these pixel dimensions, calculate the maximum reproduction size of the file by dividing the number of pixels by the ppi required. For example, if a color or grayscale image file’s dimensions are 900 × 506, this image can be reproduced as an image measuring 3 × 1.68 inches or smaller (900 ÷300 = 3 and 506 ÷ 300 = 1.68).

Taking an existing digital image and increasing its dimensions or resolution does not add detail to the image. Because the number of actual pixels in an image cannot be increased, its dimensions and resolution are proportional—that is, when you raise one, you decrease the other. Therefore, when an image is too small, increasing the resolution or dimensions will not make the image useable.The examples below show the same image viewed two ways. An image with 432 × 396 pixels is6 × 5.5 inches at 72 ppi resolution (left). But at the 300 ppi resolution required for color or gray-scale print production, the maximum size of the image is only 1.44 × 1.32 inches (right). And at the 1200 ppi resolution required line art, the dimensions would be even smaller.