|Posted by caseycrockerphoto on April 22, 2010 at 6:11 PM|
Photo Fusion One:
P a n o r a m i c s
(written for Camren Photographic's August 2009 Newsletter)
There are two uniquely digital fusion techniques widely accepted for their sleight of hand and fascinating illusion. These fusion techniques are the Panoramic Stitch and the High Dynamic Range Merge. These two photo fusions require previsualization. If this does not occur, exposures or the image overlay could easily be inaccurate, resulting in a less than successful image. Also in the case of panoramics perspective might have to be adjusted or a great deal of cropping will have to occur, so fine tuning an approach to these techniques helps circumvent possible problems. Over the next two months, the panoramic fusion (stitching) and the high dynamic range fusion (HDR) will be explained in what aims to be an easy to apply methodology. First up is the panoramic photo fusion.
Panoramics are often seen as unique, encapsulating, and immersive depictions of a setting. Their very form is distinct from the typical 4x6 or 8x10 format. Using a wide format such as the panoramic is like a magic trick or an illusion. And the technique has been used for over a century. Today, we have the benefit of technology, whereas before the process was quite intense requiring images to slowly be assembled together , dodged, and burned to perfection in the darkroom.
Please click on the above image to see images and screen shots of the process described below. (Keep in mind, there are two pages of illustration.) The photograph is of Zapata Falls, near the Great Sand Dunes National Park. The example image above is a panoramic consisting of two images. Even though a classic pano is longer than two images, assembling two images is as easy as three or five images fusion. The idea behind this illustration is the importance of technique.
This tutorial expects that several, ready to fuse photographs already exist. However, here is a quick start to shooting for panoramics: Use a tripod and do not use a polarizer. Set your camera however you wish, but be sure to repeat the same exposure setting over and over for each image. Typically, images shot in an auto mode vary in exposure and will effect your image corrections later in the process. Use a normal focal length for your camera and level your camera so that when you swing the camera to take a succession of photos the images will align well. Be sure to stop fully between images and give some over-lap room. This way they photos will be sharp and the program will know where to stitch the seam.
Current technology allows the panoramic photographer to assemble multiple images together into a single elongated picture through a computer. This fusion technique is called “stitching.” For several years, programs, such as PTGUI, Panotools, and Adobe Photoshop CS2, 3, and 4, have “stitching” or “merge” capabilities. These programs allow you to tell them where the images that need to be assembled are. CS3 & 4 allow you to simply open them, then run an automation (click file, then automate, then photomerge). The programs will then prompt for a type of correction. An interactive photo-merge is a good choice, just in case the automated stitch needs some tweaking, such as perspective adjustments or a moving of the pieces that will make up the panoramic puzzle.
One reason a dual-image photo fusion, such as this, is a good idea is because it increases the resolution of the image beyond the resolution of the camera. For instance, the image was shot with a Nikon D200 with two 10.2 megapixel images. These two images combined effectively give 15 megapixels. (Take a panoramic with four images and a 20.4 mp image results). In this case, the camera was up against a wall of people, so backing up was not an option, nor was widening the focal length of the lens away from 35mm. (If a focal length beyond 35mm is used then normal perspective is lost, vignetting occurs, and significant cropping will have to happen. So, panoramic images work best when a “normal” lens is used.) This waterfall situation repeats an often problematic, but compelling situation than when trouble-shot using this dual-image panoramic technique results in a high resolution, wider than available photograph.
Low to the ground, the first picture was taken, then the camera was simply moved up and after incorporating a little overlap area the second was taken. The rock and the waterfall were both important subjects. The same camera settings have to apply or else exposure becomes an issue. (Camera settings were as follows: Nikon D200, ISO of 200, 2x neutral density filter to slow the shutter, 4 second shutter value, aperture value at f/16, and white balance set to cloudy day, or 9000K). So, this picture benefits in two ways: the lens appears to be wider than it really is and a near doubling of resolution occurs. Color fidelity increases, as does contrast and overall image sharpness. The panoramic fusion offers a technique that is truly different and is far greater in quality than simply cropping an image to look elongated. The panoramic fusion will trick the eye because it will actually include what appears in the peripheral vision.
Click here for illustrations: