How do I when the user presses a button, he will choose an image from his phone ?

I want when the user presses a button, he will choose an image from his phone, and when he presses a second button, he will download the image

Hello,

You might want to look at the File Chooser plugin.

I haven't used it myself but it allows you to choose a file or image from your device, read the file or display the image.

Not sure what you mean by download it, as it already exists on the users device.

When modifying the image in the program, the user may want to download it