How to make high-res figures for a paper

So you’ve written your paper and made beautiful PowerPoint graphs of your data, and some explanatory schematic diagrams, and it’s all good to go. You log onto the submission website, upload your manuscript and then start on the figures.

At this point you encounter the requirements for the figures, which, admittedly, you should have checked earlier, but you didn’t. So now you discover that the figure has to be 600 dpi (dots-per-inch) and exactly 8 inches wide, and in bitmap form: jpg, tiff etc (a bitmap is an image encoded as coloured pixels, as opposed to vector graphics which is a set of rules for drawing lines etc).

OK, well, no problem, your figure is in PowerPoint so you copy the figure and paste it into your bitmap editor (such as Photoshop, or – my favourite – paint.NET) and re-size it to 600 dpi with the image sizing tool. But now it becomes only two inches wide! So you change the image size to 8 inches but now it looks awful – blurred and fuzzy.

For a given image, there is an unavoidable trade-off between resolution and size – if you increase the resolution you decrease the size, and vice versa. This is obvious when you think about it, because to make an image bigger the program has to insert extra pixels to maintain the dpi, and it has to “guess” (interpolate) to know what colour these should be. To enhance both resolution and size elegantly you need a bigger image. OK, so you go back to PowerPoint and enlarge everything. But now the graphs look awful – the lines and text didn’t scale accordingly and now they look tiny and spidery. So you spend half an hour re-sizing all the lines and enlarging all the text, having to re-position quite a few things, and then try again. Now it works.

Dear god, you have twelve figures… is there a better and faster way to achieve the same thing? Yes there is! That is to make use of an image format in PowerPoint called Enhanced Metafile (EMF). EMF has the advantages of both a bitmap and vector graphics – it lets you scale everything up without altering the relative sizes of lines and text, but it “knows” that lines and text should remain sharp so the re-scaling preserves the nice crisp clarity of your graphs. So here’s a quick way to make a nice, high-res. picture:

1. Select everything that’s to be part of it (if it is the whole page, ctrl-a is a quick way to select-all)  and copy (ctrl-c).

2. Create a new blank slide and paste the copied figure into it as an Enhanced Metafile. You can do this with paste-special or (quicker) ctrl-alt-v, then select EMF. Now your figure will be pasted in as a single image.

3. Now you need to rescale it. You generally need to do this quite a bit, so slide the zoom slider all the way down to the left so the slide shrinks relative to the surrounding workspace. Move your image up to the top left-hand corner of the workspace, and then rescale it by dragging the bottom right corner until the image takes up most of the workspace (the exact amount of rescaling doesn’t matter at this stage so long as it is bigger than you will ultimately need). Then select the image and copy it.

4. Open a new file on paint.NET (or whatever), set the resolution you want and paste your figure onto the new page it makes for you. You might run into a problem if the rescaled image is too big (in megabyte terms) for your clipboard (the thing that holds the image in “working memory” between the copying and pasting). If this happens and you get a clipboard error, you may need to save the image as a bitmap straight from PowerPoint onto disk, then insert from the saved file into paint.NET. PowerPoint will only save that part of the image that is within the slide boundary, so you need to enlarge the slide (maybe create a new file so as not to mess around with the one your graphs are in) and set a custom slide size as big as you can, making sure your image fits within its boundaries.

5.  Now scale the image down to the size you want (if it was already smaller, you need to go back to PowerPoint and enlarge the EMF image a bit further). Then save in the format you need. Voila! A nice, high-res picture.

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This entry was posted in General, PhD students, Practice of science and tagged , , , . Bookmark the permalink.

One Response to How to make high-res figures for a paper

  1. Guest says:

    or just.. don’t use PowerPoint for figures…

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