Why is the image created by HDR Efex Pro 2 smaller than the original images?
When the Alignment option is selected, HDR Efex Pro 2 will analyze each image in the image series and determine if the images are not properly aligned. If one or more images are not aligned, HDR Efex Pro 2 will reposition and or rotate the images so that all images become aligned. If any images are repositioned or aligned, then HDR Efex Pro 2 will take the common areas from all images and use them for the final image. During this process, some image data may be cropped away. This is normal in the alignment process.