I wonder what's the fastest method in the universum to input an image from clipboard to a Choose a file dialog:
Use: Shift + Command + 3 to save your captured image to the download folder.
Using: Shift + Command + 4 you can make a selection.
If the dada is in Clipboard you can open the clipboard viewer, select the data (could be an image or whatever), click the button Save data and it will be saved in a folder. Now you can access it.
Clipboard viewer image below: