Applies a convert('RGBA') operation early to mimic previous behaviour.

            if image_mask is not None:

                if self.soft_inpainting is not None:

                    # We apply the masks AFTER to adjust mask based on changed content.

                    self.overlay_images.append(image)

                    self.overlay_images.append(image.convert('RGBA'))

                    self.masks_for_overlay.append(image_mask)

                else:

                    image_masked = Image.new('RGBa', (image.width, image.height))