Preparing TIFF-images for publication

Transcription

1 Jesper Wiklander: Managing digital illustrations in publications 1 Preparing TIFF-images for publication There are 4 basic steps: 1. Check out the author instructions for the journal where you intend to publish your paper. 2. Get your images with sufficient dimensions (number of pixels). 3. Set the images resolution to the desired print size using some graphics editor such as Gimp, Photoshop or Paint Shop Pro. 4. Insert the images into yor manuscript. 1. Author instructions Most journals should have (more or less detailed) instructions for authors regarding the preparation of manuscripts. In addition to instructions on the layout of the manuscript (formatting references, different sections and headings etc.) there are usually also instructions on how to prepare the illustrations/figures/artwork used in the article. This can include acceptable file formats, print size and resolution. See the homepage of the intended journal. Many journals will accept illustrations made in for example Microsoft Excel, Graph Pad Prism and CS Chemdraw. Although pasting these types of pictures directly into a manuscript in Word may work well, in my experience this often leads to strange behaviour such as selfresizing diagrams or images that jump around in the document (in particular when multiple authors with different Office-versions send a manuscript back and forth). Since most journals also accept bitmapped images (TIFF-files usually) I recommend this format simply because I find it easier to work with. The size of the illustrations in a journal article is determined by the layout of the particular journal. If no instructions can be found regarding print size, look through an issue of that journal and measure the illustrations (1 inch = 2.54 cm). Resolution is often referred to as DPI, dots per inch (sometimes PPI pixels per inch). This is the factor that determines the size of an image when it is printed. The higher the printing resolution for a given image the closer the dots (or pixels) will be printed. This results in a smaller and sharper printout. Printing at low resolution will yield larger but less sharp images DPI 5 5 cm DPI 4 4 cm DPI 3 3 cm

2 Jesper Wiklander: Managing digital illustrations in publications 2 It appears to be quite common for journals to request a resolution of 600 DPI so use this as a guideline if your journal doesn t give this information. Sometimes a journal may require different resolutions for line-art (black and white) and raster images (colour or greyscale). When the resolution and print size (width usually) are known it is easy to calculate what dimensions the image file should have by simply multiplying these numbers. A 3-inches wide image at 600 DPI thus requires 1800 pixels. 2. Getting the image file Save/export as TIFF The easiest way is to save or export your illustration to a TIFF-file if the program where it was created has this option. This is possible in for instance CS Chemdraw and Graph Pad Prism. This option can usually be found under [File Save as] or [File Export]. With a bit of luck it is even possible to choose the resolution

3 Jesper Wiklander: Managing digital illustrations in publications 3 Print to PDF using Adobe Acrobat If you are unable to save the illustration directly as an image file you can still get a TIFF-file as long as your program can print. With Adobe Acrobat (note: not Acrobat Reader) you can create high resolution PDF-files from which it is possible to capture the images. With Adobe Acrobat installed there will be a printer called Adobe PDF. The procedure is as follows: 1. Open your diagram/illustration in the program where it was created 2. Open the print dialogue (usually [File Print]) 3. Choose Adobe PDF as the printer 4. Then click on Properties to access the PDF options 5. Choose Press Quality under Default Settings 6. Click the Layout-tab and then Advanced 7. Make sure Print Quality is set to 2400 DPI 8. Click Ok all the way back to the first print dialogue 9. Finally, print the illustration. You will be asked for a filename and location for the PDF-file. The next step is to capture the image from the PDF-file. Open it with either Adobe Acrobat or Acrobat Reader and follow these steps: 1. Zoom in (the more you zoom the larger image dimensions you will get) 2. Select the Snapshot Tool (looks like a camera) 3. Draw a box around the image while holding down the left mouse button (start in the top left corner, the page will scroll when you reach the edges) 4. When you have passed the lower right corner of the image, release the mouse button 5. A popup-window will say that the selected area has been copied to clipboard Then open a graphic editing program such as Photoshop or Paint Shop Pro. I use PSP but the procedure should be more or less the same in other programs. 1. [Edit Paste Paste as new image] 2. [File Save as], choose TIFF-format Scanning If you only have hardcopies of the illustration such as gels, photos and instrument printouts you need to use a scanner in order to get digital images from these. Just make sure that the scanner is set up to scan at a sufficient resolution. Note: if your hardcopy is larger then the final size for publication you can scan at a lower resolution (using the previous example and your gel is 6 inches wide you should set the scanner at 300 DPI to obtain an image that is 1800 pixels wide.) 3. Setting the resolution In many cases it is difficult to get the correct dimensions and resolution right away. The initial TIFF-file often has larger dimensions than necessary. Furthermore, if it was obtained using Adobe Acrobat as described above, the resolution after pasting the image will be 72 DPI. This can be fixed using your graphics editor.

4 Jesper Wiklander: Managing digital illustrations in publications 4 Cropping the image If the image contains unwanted areas (if for example you selected a larger area than necessary in Acrobat) these can be removed using the Crop-tool (looks like this in PSP: ). Select this tool, drag a box around the area that you want to keep and double-click inside this box. If you're using Gimp, simply click on Image then Autocrop. Resizing and setting resolution This is done using [Image Resize] (or Shift-S) in PSP: Before: After: In this case, the original image was pixels at a resolution of 72 DPI. This corresponds to a printing size of roughly inches. However, we want a 3 inch image at 600 DPI so this has to be changed: 1. Since 3 inches at 600 DPI corresponds to 1800 pixels and the current image is larger, the Resample function is required to alter the dimensions of the image. According to the PSP manual Bicubic resampling gives best results so use this. (Resampling will always degrade the image quality somewhat but at these high resolutions this will not be visible to the eye when the image is printed) 2. So select Resample and then simply enter the desired print width and resolution (also make sure that Lock aspect ratio is checked, otherwise the image may be distorted) 3. Entering a width of 3 inches and a resolution of 600 DPI will automatically change the dimensions to the corresponding values. 4. Hit OK and save the image.

5 Jesper Wiklander: Managing digital illustrations in publications 5 Note: If the image already has the correct dimensions and you only need to change the resolution, uncheck the Resample box. 4. Inserting the image into MS Word Once the image has been saved with the correct dimensions and resolution insert it into your manuscript using [Insert Image From file] Final result: 3 inches (7.62 cm) That s it really! I suggest you play around with these things in order to find a method that works well for you. For example, depending on the size of a diagram in Excel more or less zoom is required in Acrobat to get the proper image dimension. It s always better to get an image with a larger number of pixels than required as opposed to one with too few. This is because the resample function is better at removing pixels than it is at adding them. You will also need to figure out what font sizes to use and so on. Good luck! Jesper Wiklander