Understanding Open Paths in Vectors

Many beginner illustrators wonder, what to do with open paths in vectors. Novices often face rejections due to open curves. Many photobanks provide explanations on their websites about resolving the issue of open paths in vectors, but I believe this topic needs further clarification. In today’s article, I will attempt to explain why it is so important to avoid open paths in vector illustrations and what exceptions photobanks may have for accepting works with open paths.

Why Is It Necessary to Worry About Open Paths in Vectors?

Most experienced illustrators do not think about unclosed objects. As long as the vector illustration looks as intended, it does not concern anyone. Moreover, if you do not encounter problems using your vectors in your own design solutions and printing, everything is fine. Usually, the main issues may arise when another designer uses your vector. For example, this could be in the case of selling vectors. The author of the vector illustration cannot track the fate of their illustrations, but the photobank administration must ensure that buyers do not encounter problems using the purchased vectors.
For example, look at the illustration provided in the image just below. In this image, you can see open paths with a thick black outline. As you may have already noticed, even open paths can be filled with color, gradient, or pattern. This is not a problem if that is exactly what you intended and only you will use the file. But in other situations, open paths can become an issue.

Open Paths After Filling

The light blue square in the illustration below looks like a closed object, but as soon as a thicker outline is applied, it immediately becomes clear that its points do not connect. Remember that a designer may need to enlarge the illustration or change the outline thickness. In the case of unclosed paths in the illustration, the final result can be completely unexpected. Additionally, there are other effects that do not behave as they should when open paths are present. Further editing of all unclosed paths by the designer after purchase can be lengthy and quite costly.
Open Paths Become Visible with a Thicker Outline

There Are Exceptions to the Rules

Unfilled unclosed objects can be acceptable and permissible. For instance, if all paths have outlines and no fill. Below is an illustration where it makes sense to leave an unclosed outline.
On graph paper, the line thickness is 0.25 pt, which is the finest outline in printing. If a designer decides to reduce the illustration, these lines may become unprintable. By leaving them as outlines, the author helps the designer or printer easily adjust the line thickness. Don’t forget the convenience for the designer when leaving unfilled paths open.

Lines Can Stay Open if They Have No Fill

An important note for designers: If you are working in Illustrator, do not forget to ensure that the Scale Strokes & Effects option is active in the settings. Thus, when you increase or decrease the vector illustration, its outlines will change proportionally.

Finding Open Paths in an Illustration

Now that you know everything about open paths and their drawbacks, as well as in which situations they are acceptable, how can you detect them in your illustration?
The simplest way to detect open paths is by using the free Select Menu plugin from Graffix Software. Choose Select&Open Paths from the menu, or better yet, assign keyboard shortcuts – and all open paths will be displayed. The Select Menu plugin does not differentiate between filled and unfilled paths; it simply shows the location of open paths.
However, of course, not everything is as simple as it sounds. If open paths are locked or hidden, the Select Menu plugin will not be able to highlight them. Additionally, guide lines are also open paths, but the Select Menu plugin will not highlight them (guides will not be a problem during file approval by stock inspectors, but if desired, they can be removed before submitting files).
Not the simplest, but the most reliable way to identify the presence or absence of open paths in a file is through the Document Info panel (Window&Document Info) in Illustrator. Here, all significant information about the illustration is displayed, including the number of open and closed paths. From the drop-down menu on the Document Info panel, select “Objects” and uncheck “Selection Only” to encompass the entire file at a glance.
Select “Selection Only” if you wish to check a specific highlighted part of the file. If you encounter difficulties selecting the desired path, simply use the Document Info panel. Select the object or layer, and if the info panel indicates that all selected paths are closed, hide that object or layer, then move on to the next one. And don’t forget to remove all guides.

Closing Paths

How to close discovered open paths? If there aren’t too many open paths, illustrators often use the functions of the Pathfinder panel for step-by-step path closure. A recently discovered trick is to select the Knife tool, then draw a circle around the illustration. Filled objects will close. Paths with zero fill will remain open.
There are also several plugins and scripts for closing paths. For example, the Point Control plugin for iMac, which includes an option to close paths.
There are a few more scripts at http://www.pictrix.jp/ai/ClosePnt/ClosePts.zip (clicking the link starts the download immediately), although they have no accompanying documentation. Scripts need to be installed in the Adobe Illustrator/Presets/Scripts folder. After installation, they will appear in the File -> Scripts menu. For additional information about the scripts, refer to the documents in the Scripts folder within the Adobe Illustrator folder.

Dealing with Open Paths

There are often situations where open paths appear even when you are 100% sure they shouldn’t have. Open paths frequently arise after resaving a vector illustration file in EPS version 8. For example:

• Simplifying a closed path (Object>Path>Simplify) will make it open. Why this happens, I don’t even know;
• Flatten transparency. In addition to other unpleasant things, using this effect can lead to the appearance of open paths;
• Applying Align stroke to the inside and Align stroke to the outside (for outlined objects) – a function on the Stroke panel – will create open paths when saving in 8 EPS, because this object will undergo expansion;
• The same goes for adding a stroke through the Appearance panel. When subsequently applying expand, open paths arise;
• Standard brushes. All strokes of standard brushes need to have expand applied to them; otherwise, they will produce an open path (in Illustrator versions up to and including CS3).

I know I didn’t have open paths, but my vector wasn’t accepted!

We’ve all been through this. This can be due to three reasons:

1. The author didn’t check the illustration for open paths or the open paths were locked or simply hidden.
2. Just an inspector error. Yes, stock photo inspectors are human too and make mistakes, although they never admit it. In this situation, double-check your file, upload it again, and work on something else.
3. Open paths arose from saving in an earlier version (like 8 EPS).

For one of the three listed reasons, some paths become open when you resave the file. The only way to avoid this is to save the file, close it, reopen it, and check it. Yes, this takes extra time, but it’s better to do more upfront than to spend even more time re-uploading the file later. By the way, I believe that now that you understand how and where to look for open paths and how to prevent their occurrence, your acceptance rating at stock photo agencies will only improve!
Here’s a algorithm for detecting open paths in your vector illustration:

1. Create a fantastic illustration. Don’t forget to save it.
2. Unlock all objects (Object>Unlock All). Show all objects (Object>Show All).
3. Zoom out to check if any objects are outside the page limits.
4. Now check for open paths in Document Info. If you don’t find them, immediately read point 8.
5. Check for open paths using a plugin.
6. Close the identified open paths that need closure.
7. Check again for open paths in Document Info. Look for transparencies, symbols, patterns, and other elements that require expand to be applied.
8. Save the file in 8 EPS version.
9. Close the file and reopen it, checking again for open paths. If you find filled open paths, go back to point 2. If everything is clean now, proceed to the last step.
10. That’s it, now upload your work to the stock agency. Good luck!