When making an ad or powerpoint, having the topic stand out is most important. Having it boxed or circled draws attention to what the designer wants the reader to see. Adobe Photoshop can be an important tool in making this a reality.
Inserting text is usually a given when creating a brochure or an ad. You have a picture in your mind of how it will look but it can be frustrating to have your end product match your vision.
To display an image in black and white will require the entire image to be displayed as such. The benefit of using black and white allows you to introduce color to specific areas of an image, which makes catches your eye and allows those specific areas stand out.
This is a concept that is used by many industries, such as makeup companies, hair companies, etc. They use the images to draw the consumer’s focus to the specific product, or product results, rather than the whole picture itself.