With the custom component in the power apps, it makes the app makers easy to share an update one or more components with other makers. 

A component library is a centralized and repository of components for usability. 

The below video shows, an example of creating a custom component called emotional rating component. Which can be used, across all the apps to rate a particular product. 

Step 1: Create a sample data entity as shown below. It uses EcoResProductImage table which holds the image container of the items.

Step 2: Check the odata feed in the browser. You can see the Base64 images are exposed in “MediumSize” field as shown below.

Step 3: Create a sample PowerApps application and add a gallery. Assign the data source to the gallery.

Step 4: Assigning the “MediumSize” to the image will not shows up the image in PowerApp. So add the below code in the image source to specify the Base64.

“data:image/jpeg;base64,” & ThisItem.MediumSize