When you gather and create content for an App's section, remember that it doesn't matter if it's text, images, links or a bit of everything. All content must complement each other.
In an App designed with good visual taste, you can find a graphical connection between the different elements. It is necessary to have interrelationship which is achieved with a good combination of colors, fonts, images, layout and general line of style.
Images should be relevant to the content and contribute to a greater total image just as the colors. This is why an image has to have the right resolution, not be blurred and have the correct position and size within the layout.
In order to obtain a good resolution you should never use images that have less than 72 dpi. If you want an image to cover 100% of the screen width, we recommend you to use images with a width of 1024 pixels. For icons of, for example, the menu bar, we recommend a size of 512x512 pixels. The recommended formats to use for your images would be JPG and PNG for images with transparent sections which can offer a cool visual effect.
But remember that an App should never be more than 50 Mb in total size, and the more images you use (and the bigger they are), the greater the size will be and therefore less performance. 
Design and content
