How to Vector an Existing Image
Vector graphics are used in logos, illustrations, as well as images. Although this may not be apparent to people who don’t work with photo editing, vector images play an essential role in website design, graphic design, and commercial marketing. For the most part, vector images are created from scratch. However, you can try and convert any image into a vector image.
Bitmap and Vector Images
In order to fully understand how to “vectorize” an image, you need to comprehend the difference between the bitmap and vector images.
Frequently seen and sufficiently basic to begin with, bitmap images are expressed via, well, bitmap (.JPEG, .PNG). This means that they use pixels in columns and rows made of different colors and different shades of the same color in order to display the image. Add a large number of tiny pixels and you’ve got yourself a clear picture. The smaller the pixels are, the clearer the image will be.
However, this is what makes bitmap images resolution-dependent. Every time you try and resize the image, the quality will change. This isn’t ideal for website and graphic design. For instance, when you need to change the image size a multitude of times (layers, etc.) It goes the same for commercial marketing.
The entire point of vector images is to solve the resolution dependency. Because they are path-based, vector images are easily scalable. This means that they consist of math equations, meaning the image is essentially made up of strings of data that a computer program can recognize and display. Although fully scalable and easy to edit, vector images never look photo-realistic. On the other hand, components and shapes of vector images can be retooled and resized, without ruining/destroying the image.
Converting to Vector Images
To turn a bitmap image into a vector image, you’ll have to use video or image editing software. Primarily, Adobe Illustrator is a vector graphics editor you can use, but you can vectorize an image by using Photoshop and Gimp + Inkscape, as well as many other photo editing programs.
Illustrator was actually developed by Adobe for vector images. Although it is commonly used for creating vector images from scratch, it can also help you turn your bitmap image into a vector. Vectorizing images in Adobe Illustrator is pretty straightforward.
First, open the bitmap that you want to convert in Illustrator. Now, go to the Live Trace option, found in the Control Panel. Navigate to the Tracing Presets and Options and access the menu. The existing options allow you to choose which setting you want to use to vectorize the image. You might want to create a different path for every color. To do this, click Expand in options.
Go back to the Tracing Presets and Options menu and go to Tracing Options. From here, you can customize each path and its settings like Blur, Mode, and Threshold. Now, simply click Preview and you’ll see how the changes affect the vector image that you’ve just created. Modify the paths and play around with the settings.
By default, Photoshop is a tool used for manipulating bitmap images. That being said, Photoshop can, indeed, vectorize images. It may not be as simple and straightforward as when using Illustrator, but it is possible.
Open the image in question in Photoshop. Then, navigate to the Window menu and then to Paths. In the options bar, you’ll have three tools to choose from: Pen (for straight lines), Bezier (for curves), and Freeform (free hand drawing). Use the Magnetic Pen tool for following brightness and color transitions in the image.
To start off, draw vector paths until you see a traced conversion of shapes and paths within your images on the screen. Press Enter to end the pathway. Use the Marquee, Lasso, and Magic Wand tools to select the rest of the pathways. To make a selection of a vector pathway, navigate to the Paths panel and select Make Work Path.
Now, you need to set tolerance for the pathways. The smaller the tolerance levels of a path, the more tightly the path will adhere to whatever you’ve traced. Use large levels for smooth transitions. Be careful, however, if you don’t name each path and accept its default name, each new action will replace the previous one when drawing vectors.
Finally, export the vector paths that you’ve made from Photoshop to Illustrator. Do this by clicking File -> Export -> Paths to Illustrator.
Gimp + Inkscape
Gimp is a free, open-source photo editing tool. Also free and open-source, Inkscape is a vector graphics editor.
First, open the photo in Gimp and navigate to the Rectangle Select tool. Outline the image part that you want to vectorize with this tool. Go to the Image menu and then click Crop to Selection. This will remove everything around the area you selected. Go back to the Image menu and click Autocrop to “tighten things up.”
Now, export the file to Inkscape. Do this by going to Gimp’s File menu in the main upper toolbar and selecting Export As. Do not change any export settings.
Now, load the file in Inkscape, click on the image to select it, go to the Path menu, and click Trace Bitmap. In the window that opens, enter your preferred settings and click Update. Click the Update button after every change in this window and click OK when done. To make some finer adjustments, select the Edit paths by nodes tool and try the Break Path tool if any nodes need separating.
Finally, save your image as a vector file and that’s it!
Whatever you need a vector image for, there are tools that can help you. Although the Adobe Illustrator and Photoshop are the most powerful, the free Gimp + Inkscape alternative can be just as efficient if you’re patient enough.
What tool do you use for vectorizing your images? Do you always start from scratch? Feel free to discuss in the comments below.