Adding text to slide images is a common practice. This practice has become a go to design hack as people move away from traditional slide layouts.
Done well it really enhances the individual slide and focuses the point the presenter is trying to make. Done badly, well, it just leaves the audience unimpressed and frustrated.
Here are four tips for adding text slide images that show what to avoid and how to get great results.
Overlaying Text onto an Image
Overlaying text onto an image is probably the most common way for adding text to slide images. If you’ve attended two or more presentations that included a slide deck, you’ve probably seen this technique.
The concept is straightforward. Basically, you place a text box over an image on the slide.
Where people go wrong...
is using a bad combination of text color and image opacity (also called transparency). Many times, presenters don’t accommodate for color adjustments when projecting. What looks great on a computer screen doesn’t always translate through the projector.
Another mistake...
is thinking that just using either black or white text color is all that is needed for placing text over an image. Unfortunately, the more detailed your image, the more it competes with your text, regardless of its color.
To avoid these mistakes...
the key is using opacity either on your image or as the text box background. On its own the original image is quite beautiful and would project quite nicely. However, the level of detail in the image makes it difficult to read text if one is just using white or black text color.
Bad examples of Adding Text to Slide Images

Use of Black Text Color
Most people wouldn’t place black text on this image. However, this color tends to disappear on images like this regardless of where it is placed.

Use of White Text Color
Using white text, while better, still isn’t great. However, this is what presenters do most often.
Good examples of Adding Text to Slide Images

Adjust Image Opacity
This example shows how image opacity improves the readability of the text. The image opacity/transparency is set to about 70%.

Textbox Transparent Fill
Another way to create better readability is using a transparent text box fill. The fill is a dark gray set to about 50% opacity/transparency.

Transparent Shape Fill
A variation of this technique is to use the triangle shape placed in a corner. The fill in this example is set to about 20% opacity/transparency.
Adding Text to Image Negative Space
Another tip for adding text to slide images is to use “negative” or blank space of an image. Granted, most images don’t have this option. If you find one that has good negative as well as does a good job in helping convey your message, it can be quite effective.
The key is to make sure your text is in balance with your image.
More often than not the amount of negative space influences how much text you should use. Additionally, the negative space doesn’t need to be devoid of imagery. It just needs to be minimal enough not to compete with the text.

Use of Image Negative Space
In this example, the image’s negative space has sufficient space to have more text. However, it is right on the edge of being too much text. Being succinct is important

Minimal Use of Text
This example shows how minimal use of text is still impactful even though there is quite a bit of negative space.
Create a Side-by-Side
When adding text to slide images, sometimes the overlay technique isn’t the best choice. Or the image doesn’t have enough negative space. In this case, a good strategy is to just put the image and text next to each other - a.k.a side-by-side.
This can be done either vertically or horizontally. The easiest way to do this technique is to add an image as a fill to a shape instead of the slide background. Most presentation applications include this option.
Horizontal

Vertical

Use of Decorative Fonts
There are tons of cool fonts out there. However, for adding text to slide images, avoid using overly decorative font or a script font that has lots of flourish.
These are difficult to read especially for an audience who is viewing the slides at a distance. Also, it detracts from the overall visual impact and the message you are trying to convey.
Example Font: Braggadocio

Example Font: Kunstler Script

Conclusion
Visual impact is an important element of slides. One easy way to have this effect is by adding text to slide images. The key is to ensure there is enough contrast between the image and text to ensure your audience can read the text.
Additionally, contrast can be achieved in a variety of ways by adjust transparency of the image and text box fills, using negative space on image, or by placing the image to the side of the text.
Other Resources
If you are looking for some additional tips on creating a great slide deck check out Pat Flynn's YouTube video highlighting his techniques. If you find yourself short on time, check out this post on how to create a slide deck fast.
In the comments below, share any specific techniques you use to make text added to a slide image visually impressive.