PNG files are natively supported by Android devices. Use Android's Gallery app to view and edit PNG files.
Tap the Apps icon to show icons for all apps on the device. Tap the Gallery icon to open the app.
Gallery organizes images into albums associated with the folder the image is located in. For newly downloaded images, the album is usually labeled "Pictures" or "Downloads."
Tap the album to see thumbnails of all images in that album.
Tap on the thumbnail for the PNG file to view the full-sized image. To apply edits to the image — such as cropping, resizing, and color effects — tape the Pencil icon on the bottom left.