International Journal of Quantum Chemistry
Copyright © 2015 Wiley Periodicals, Inc., A Wiley Company
Online ISSN: 1097-461X
Associated Title(s): Journal of Computational Chemistry
2 Types of images
3 Bitmap images
4 Vector graphics images
5 Submitting images and copyright
The purpose is to inform you how you should prepare the images in your manuscript for submission so that:
a) the images in you manuscript are the highest quality possible, and
b) delays in production between acceptance of your manuscript and printing are minimized, resulting in a faster publication time for your paper.
Please contact the editorial ofice at email@example.com, and we will do our best to help.
Images for publication can be classified into two main categories: bitmap images and vector graphics images (Figure 1).
|Figure 1. Examples of bitmap (top) and vector graphics (bottom) images. Bitmap image from Y. Jun et al., Adv. Mater. 2005, 17, 1908. Vector graphics image from X. Yin et al., Adv. Mater. 2005, 17, 2006.|
In a bitmap image, the information of the image is stored in a grid of pixels, in which the color of each pixel is defined as a combination of red, green, and blue. (A bitmap image should not be confused with the .BMP file format, an older file format used internally by Microsoft Windows.)
Typical bitmap images include photographs, optical microscopy, and SEM, TEM, and AFM images.
In a vector graphics image, the information of the image is stored as a set of geometrical primitives, including points, lines, curves, and polygons. The color of each primitive is also defined as a combination of red, green, and blue.
Typical vector graphics images include plots, graphs, chemical structures and reaction schemes, diagrams, and schematics.
The advantage of vector graphics images over bitmaps is that they can be scaled without a loss of quality (Figure 2), since geometric primitives are defined mathematically. A curve can be scaled by 1000% without inventing any new information. To scale a bitmap by 1000%, new pixels have to be invented to insert between the original pixels.
|Figure 2. a, b) Bitmap image at original size (a) and enlarged 1000% (b). c,d) Vector graphics image at original size (c) and enlarged 1000% (d).|
Some images cannot easily be defined by geometric primitives more complex than single points, because each point (or pixel) in the image is a different color, making up the image. Photographs, micrographs, and similar images can only be represented as bitmaps.
Bitmap images can be produced by image-capture applications such as flatbed or film scanners, video frame grabbers, microscopy accessory software, digital cameras, and CCD video cameras. Bitmap images can then be edited by applications including Adobe Photoshop, Paint Shop Pro by Corel, and the open-source GNU image manipulation package.
All bitmap images should be submitted as TIFF (tagged image file format) files. The TIFF format is a widely used file format and is supported by most applications. Unlike other bitmap file formats such as JPGs, TIFFs can be opened, edited, and saved without suffering losses in quality due to recompression.
Our printers require images to be submitted at a resolution of at least 300 dots per inch (dpi). The width of the image in dots, or pixels, depends on the width of the image when it is printed in the journal.
Images are usually printed as either one column wide (8.5 cm, or about 3.35 in) or two columns wide (17.8 cm, or about 7.01 in), so:
One-column images should be 300 dpi x 3.35 in = about 1000 pixels wide.
Two-column images should be 300 dpi x 7.01 in = about 2100 pixels wide.
The height of your image will vary, depending on what you are presenting, but nearly all images appear in the journal as either one column or two columns wide.
If your instrument produces an image less than 1000 pixels in width (for example, some atomic force microscopes), do not artificially increase the resolution—no new data will be added, and the noise level may be increased. When you submit the image, bring it to our attention that this is the maximum size image that your instrument will produce.
On the other hand, if there is a way to produce a higher-resolution image, then you should take the time to obtain the image again at a higher resolution by rescanning it or recapturing it to ensure the highest-possible reproduction in print.
You can submit images at resolutions higher than 300 dpi. However, resolutions higher than 600 dpi probably will not improve the image quality further. In addition, higher-resolution images result in larger image files, which take up more storage capacity on disk, require more memory to edit, and will take more time to upload when you submit your manuscript.
You can, but it won't produce an image that is as high quality. JPG is a lossy file format that results in compression artifacts that, depending on the degree of compression, can significantly reduce the quality of the image. It is better to capture an image with a digital camera as a TIFF file or as a RAW file. A RAW file, also a lossless file format, can be converted to a TIFF file using the software that accompanies the camera.
It is not necessary to tag image files with color profiles. Preparing the image in a standard color space should be sufficient. If you have an image where the color is critical (e.g., a fluorescence microscopy image), please bring it to the attention of the editorial office and we will consult with you during the production process to ensure accurate reproduction. You may keep in mind that journals are printed in CMYK rather than RGB.
Scale bars, and the accompanying labels, should be large enough to be clearly legible when the image is printed as a one-column wide image. Text should be 10 to 12 point at the final print size (about 0.5 cm tall at the final print size).
Vector graphics images should be submitted as Encapsulated PostScript (EPS) files, Microscoft Word documents, or PDFs. A single Word document or PDF file containing all vector images from your paper is acceptable.
Depending on the operating system of your computer and the application you are using, you may be able to produce these file types without additional software like Adobe Acrobat(for example, Mac OS X). A number of software programs are able to generate and save EPS files, including Adobe Illustrator, CorelDRAW, and many others. From MS Word, PowerPoint, or Excel, please follow the guidelines in http://authorservices.wiley.com/bauthor/excel.asp.
You can prepare a Word-embedded vector graphics image in four steps (Figure 3). First, open the image in the application in which it was created (in this example, Microsoft Excel), select the image, and select Copy. Second, create a new blank document in Microsoft Word and select Paste Special. Then, in the dialog window that appears, select Picture (Enhanced Metafile) to paste the image as a vector graphics image. Finally, save the Word document containing the graphics vector image. All vector graphics images may be submitted in a single Word file.
If you absolutely must save your vector graphics image as a bitmap file, then it will need to be an extremely high resolution TIFF file: at least 1200 dpi: one-column images should be about 4000 pixels wide, while two-column images should be about 8400 pixels wide. Because of the size of the TIFF file required for this resolution, using the above instructions to produce a Word, PDF, PS, or EPS file is obviously preferred.
Plots should be formatted so that they are easy to read and consistent with house style. Axis labels and symbols should be 10 to 12 point at the intended reproduction size (one column width, approximately 8.5 cm wide). Variables should be in italics, while subscripts of variables should be in upright type. Axis labels should be formatted as "variable [units]", where the variable is in italics and the units are enclosed in square brackets and in upright type. (This system is preferred to following the variable with a slash and the units.)
4.7 Should I prepare vector graphics images intended for black and white reproduction rather than for color reproduction differently?
Yes. If, for example, you decide that a figure does not need to be reproduced in color, the lines and labels in the figure should be converted to grayscale. Two lines that look completely different in color may be indistinguishable in black and white if they both convert to the same shade of grey. Using black solid lines and dashed lines, as well as different-shaped points (squares, triangles, circles), helps to differentiate data sets in grayscale figures.
The following drawing and text settings should be used: chain angle 120 degrees, bond spacing 18% of width, fixed length 17 pt, bold width 2.6 pt, line width 0.75 pt, margin width 2 pt, hash spacing 2.6 pt, font Arial, size 12 pt.
Figures should be uploaded through your author's center in the journal submission site. All the files, with the manuscript as well, can be combined into a single archive file (such as a .ZIP file).
We discourage submitting images with insets because unless the inset is very simple, such as a plot of a straight line, it can be difficult for readers to see all the information in the inset. It is preferable to use multiple-panel images (see below) rather than insets.
If you do want to use an inset, the axis labels and plot symbols should be the same size as the main image (i.e., 10–12 point at the intended reproduction size).
If you want a multiple-panel image to have a specific layout, upload an image file containing all the panels in the layout you desire. In order to ensure high resolution, the individual panels may also be uploaded separately. Remember that the maximum width of an image is 17.8 cm, or about 2100 pixels.
It is preferable for you to label the individual panels in a multiple-panel image, as it speeds the preparation of your manuscript for publication.
Labels should be consistent throughout the manuscript, using lower-case letters (a,b,c...) in a 12 point sans-serif typeface. The labels should be consistently positioned, preferably in the top left corner of the panels. Sufficient contrast between the label and the background is necessary (black label on a white background, or vice-versa). If necessary, a white letter can be placed within a black box and superimposed on the image. See recent issues of the journal for what combinations work well.
Images for the graphical Table of Contents should capture the essence of a paper, displaying a figure or scheme that is central to the theme of the manuscript. Since images for the Table of Contents are reproduced in color at no charge, authors are encouraged to submit color figures.
Images should be formatted as 2 inches (5 cm) wide by 2 inches (5 cm) high. For bitmap images, these should be 650 pixels wide. Both bitmap and vector graphics images should be prepared with labels that are at least 10 point. The use of insets or highly complex images in Table of Contents images is discouraged, as the data in the inset may be difficult to read.
If the image is from another of your own previously published papers and you have access to the original data, then follow the instructions above for preparing bitmap or vector graphics images.
If you do not have access to the original data, but you have an electronic version of the paper, such as a PDF reprint, then please submit the electronic version, noting on which page and which figure (or part of a figure) should be used.
In most cases, you should not reproduce a previously published figure in an original article. If you absolutely must, check with the publisher of the journal or book containing the image. It is the responsibility of the author to obtain all the necessary copyright permission agreements prior to publication of their manuscript. Look for the "Copyrights and Permissions" contact person at the journal in question.
In most cases, yes. To publish in most journals, the author signs a copyright transfer agreement giving the publisher of the journal the right to print and distribute copies of the manuscript and its images. As a result, the author no longer possesses the copyright of the published image. Therefore, it is still necessary to obtain the proper copyright permission before publication of your manuscript, even if it is from your own paper.
5.9 Where can I find more information on preparing high-quality and high-impact images for my manuscript?
A non-exhaustive list of sources that describe preparing images includes
- Hans F. Ebel, Claus Bliefert, William E. Russey, The Art of Scientific Writing, 2nd edition, Wiley-VCH, Weinheim, Germany, 2004 (ISBN 3527298290)
- The ACS Style Guide, 2nd edition (Ed: Janet S. Dodd), American Chemical Society, Washington, DC, 1997 (ISBN 0841234620)
- Felice Frankel, Envisioning Science, MIT Press, Cambridge, MA, 2002 (ISBN 0262062259)
- Edward R. Tufte, The Visual Display of Quantitative Information, 2nd edition, Graphics Press, Cheshire, CT, 2001 (ISBN 0961392142)
- A Brief Guide to Designing Effective Figures for the Scientific Paper [Webinar]. UW Design 2011. http://www.materialsviews.com/designing-scientific-figures-guide.