By combining two or more rows of images, it is possible to increase the resolution of a final image through the stitching of the multiple images together. With a single frame, an image is limited by the maximum resolution of the camera (in the case of a 6.0 MP camera, this would be 3000 x 2000 pixesl, or roughly 10"x6.7” when printed at 300 pixels per inch), but by combining multiple frames, you can dramatically increase the image’s resolution.
For this example, the final image was made up of 16 separate frames, with each image recorded as a Nikon RAW file (NEF) and then processed in Adobe Camera RAW to 16-bit TIFF files. Their original file size is 3008 x 2000 pixels (or 6.0 MP), but the final assembled image measures 7536 x 5292 pixels in size (or 39 MP). The largest resolution stitch I have made to date has created a final image with a resolution of over 350 million pixels.
I made 16 images (4 rows of 4 images per row) of the composition, using a 50mm lens, and locking my focus, exposure and white balance for the entire image set. The images were made using my Nodal Ninja, with 30-40% of the image overlapping. From a 4x4 grid, I usually gain up to a 250% increase in resolution. The largest resolution stitch I have made to date has been from 59 images (6x8), but several people have several hundred images in attaining up to a giga-pixel of resolution.
Rough Image Assembly
Once the images are transferred to the computer, I open them in Photoshop, and load them all onto the same canvas, I roughly line up the images to make the composition, placing them together in the rough final position, and then I trim the canvas. This keeps the file size as small as possible - with sixteen full sized files on the same canvas, especially with 16-bit images, the file size grows rapidly, and even with large amounts of RAM, computer performance can suffer. Before assembly is complete, resolution stitches can often reach 500 mb or more, using more than 1.5 gb of RAM in the process.
Once the composition is roughly assembled, begin the final blending, working with two layers at a time, precisely positioning the top one over the lower one, using semi-transparent layers to align each carefully, and then an eraser tool to blend the edges. Once two images are combined, I flatten them into a single layer, and repeat the process, until the whole image is assembled and complete.
Final Assembled Image
The final assembled image is then cropped to the final size and, if necessary, straightened (sometimes the horizon is not perfectly straight in a stitched image). In this case, the final image measures 7536 x 5292 pixels in size, with a size of 956.5mb as a 16mb TIFF file with to the adjustment curve and layers. The image is equal to almost 40 million pixels.
Ultimately, the result of all this effort and work, both in the field and in the computer, is higher actual resolution for the final image. Where the composition as a single frame had the potential to be printed at 300ppi to 7x10 inches, the final stitched image will print to 25"x 17” in size, without interpolation.