Reducing the opacity with Keynote
Opacity refers to how close something is to being completely opaque. If the opacity is 100%, it is completely opaque. I often like to reduce opacity of an image so that:
- Text I write over the image has enough contrast so that people can quickly read it and
- The opacity is high enough that the picture is completely recognizable.
To accomplish those 2 points, I usually choose an opacity of 30%.
Reduce opacity in 5 steps
This is how to use your free Keynote to reduce the opacity of your picture:
- Click on the picture to select it.
- Click on Animate > Action > Add an Effect.
- Click on Opacity.
- Change the Opacity to a reasonable number. (I usually use 30%.)
- Click Play to check your work.
Note that after you click Play, the image will stay at the new opacity unless you click you mouse again.
In the example below, I will add text on top of an MP4 file to make a title.
1. Move an MP4 file onto an empty Keynote slide.
2. Scroll down to get some blank space so that you can see the text you are typing.
3. Click the Text icon at the top of the slide.
4. Type the title for your video.
5. Cmd A to select the text.
6. Click the Format icon.
7. Click Text if it has not been selected yet.
8. Change the font to bold with a large enough size. Click the colour icon to change the colour.
9. Drag the text to the top of the slide so that it is overlaying the video. (Note that the opacity of the video will have been reduced so that the text will show up.)
See this example of how an image can have its opacity reduced so that a title will show up.