Below is the link to a video using the inpainting tool where the picture canvas size increase and then you take part of the picture and draw on the transparent part and the steps were to Edit>Fill>inpainting>apply which will fill transparent with the part that you included in the selection matching the color overlapping to fill in the transparent area. I have tried numerous times to follow the video and when I follow them the transparent area does not fill in. It would be so nice if I could
learn the correct way to do this but every time I try the transparent area does not pick up the selected part of the original picture to extend into the transparent layer. I am working on the original layer and cannot see why this is not working? By the way I increase the canvas size equally all the way around the picture and then tried using the inpainting tool to fill in the transparent part.