Join Chad Chelius for an in-depth discussion in this video Considering contrast between elements, part of Acrobat DC: Creating Accessible PDFs (2015).
- Remember, when we talk about accessibility, we're talking about all types of accessibility, not just non-sighted users. Low-vision users are also a big part of the accessibility community. The user has the ability to see, just not 100%. For these users, it's really important that visual content in your document has sufficient contrast so that it can be easily read. You're going to hear me say this more than once throughout this course. It's important to consider accessibility at the beginning of a project instead of at the end of the project.
Having to make contrast changes as well as other changes on the back end takes more time, is harder, and costs way more money than if these things were considered at the beginning of the project. Now, how do we check for contrast? So I've opened up the file called "contrast low" on my computer and I did this to illustrate the concept. Because what we're going to do is run a full check on this document. So I'll go to my accessibility category here, run a full check, and you can see that everything is checking out okay but if we go in here you can see that Acrobat, as well as other checkers as well, leaves contrast up to you in order to check.
You can see here, let me open this up a little bit more, it says that the color contrast needs a manual check, so the Acrobat checker can't check that for us, so it leaves it up to us. We'll go ahead an close that, and so the question becomes well, how do we check contrast in a document? You certainly can't just leave it up to you. I can't look at this document and say, "Well, that looks pretty good." There are actually standards by which contrast is measured. So, I'm going to go to a couple of web pages that I want to show you that are great resources for giving you tools for checking contrast in your document.
The first one here is one that I really like. It's called "contrastchecker.com". What this allows me to do is enter your foreground and background colors for the different areas of your document and down here at the bottom it's going to tell you if it passes the different WCAG standards, as you can see there, so this if for WCAG 2.0, the 1.4.3 criterion which measures the contrast for fonts below 18 points. You can hover over all of these.
It gives you a nice description of what each one of these requirements is. In order to see if your document passes the contrast check, I'm just going to go ahead and go back to Acrobat here. I'm going to go ahead and click on the "edit pdf" button over here and I'm just going to select some text here. So I'm going to go ahead and select this text and if we click on the color that the text has applied to it, we can click on other color and it's going to give us the RGB values of that text.
So you can see it's 224, 62, and 82. If I jump back over to my checker and I click on this button here, and I enter these values in, and I go ahead and click "OK", you can see that although some of these are passing, other elements are certainly not passing the checker. If we wanted to, we can go ahead and jump back here and we can check the other color as well. Let's go ahead and highlight this text and the RGB value of this is 232, 119 and 34.
Once again, because this text is even lighter in color, we can see that only one of these WCAG standards has checked the accessibility or the contrast check. So that's one tool. You can come up here. The other one that's very similar is the webaim accessibility checker. Which is another very useful, and down here it tells you whether your color passes or fails. The other tool that I've really grown to appreciate and use more frequently than the others, is the color contrast analyzer.
This particular tool is not really a web tool, but it's actually a tool that you can download and use on your computer. You can see it's available for Windows and the Mac platform, and this particular tool once it's installed, is a very intuitive tool to use. I'm just going to go ahead and minimize this for now, and I'll close out of this, just go to my hand tool here. If you go to the application, you can see this is the color contrast analyzer.
What I really like about this is that I don't have to remember the values and here's how it works. I'll just go to Acrobat, I'm going to zoom in a little bit. Make it a little bit easier to grab these values. If I go to the analyzer here, what I can do is I can use my eyedropper tool. Then I can come over here in my document and I can click on the color that I want to compare. You can see the background is already set to white and we can see right away that all of these are failing the contrast requirements.
Let's try the brighter red over here. You can see although one of these passes, the other ones are failing. So this particular page, it needs some updating. As I've said before, you know at this point after the pdf is created, this is where it's the hardest point in which to fix this problem. So I'm going to close this document and I have another one that's open in Acrobat, which is the contrast hide document. I'm just going to zoom in on that a little bit. What I've done is I've made some modifications to the color used for the heading and the subhead here.
If we go back to that checker, you can see that we can now use the eyedropper. I'm going to pick up this color here. You can see here that all four of these down here at the bottom are passing the contrast checker. I actually made the subheads the same color here and that was a decision that I had made to make sure that we had sufficient contrast. You can see that everything is now passing. Remember, insufficient contrast will not cause validation of your pdf document to fail, but it will limit the ability of low-vision users to read your document.
I'll say it again, think about contrast up front, prior to designing your project when you can make decisions such as picking colors with good contrast. Waiting until the end will be much more work.
- Understanding the experience of users with visual impairments
- How to know if a PDF is accessible
- Setting up Acrobat DC
- Tagging content, including lists and tables
- Adding metadata, bookmarks, and alt text
- Generating a PDF with Microsoft Word
- Creating accessible PDFs from PowerPoint, Excel, and InDesign
- Controlling tab and reading order
- Adding cross-references and tables of contents