How to shoot a 24 mega pixel photo with a 6 mega pixel camera

While a 6MP or 8MP digital camera has enough resolution for most purposes, it's not enough if you want to print poster sized images. A typical 3MP camera delivers a print size of about 5 x 7 inches. A 6MP camera will be able to provide a maximum of 6.5 x 10 inches print at 300 DPI and about 10 x 15 inches at 200 DPI. A standard photo printing job is done at 300 DPI (dots per inch) and small sized prints shouldn't be done at any lower. Large poster sized prints can however be done at a lower DPI of say 200. This is because posters are viewed from a distance, and at distances of several feet away lower resolution images produce the same quality as higher resolution images. With a 24 MP image printed at 200 DPI you can get a whopping 20 x 30 inches poster. But how to achieve such high resolution with a low resolution camera?

The trick is to shoot multiple pictures of the same scene and stitch them together to create a larger picture. Four pictures taken with a 6 MP camera will result in an almost 24 MP picture. Eight pictures with the same camera will take the image size to around 48 MP.

A tripod is very helpful in such endeavors where precise alignment between the shots is desired. The aim is to shoot the scene or the subject in slightly overlapping quadrants. The overlap is necessary to help the software detect the edges and stitch them together. Too much overlapping will lead to wastage and the final image will be of a lower size than intended. The best way to do this is to divide the subject into 4 equal imaginary quadrants, since diving a scene into 4 parts is the easiest. Use two imaginary lines, one horizontally across the subject from right to left and one vertically intersecting the first line at right angles right at the middle, to divide the subject into four quadrants. Use optical zoom and the adjust the tripod height to focus on to a particular quadrant. Take help of natural objects like water level or roof edge of a building to maintain the horizontal line. All these precise measurements are desired to help the software to stitch the image without difficulty.

When taking the pictures don't use the Auto Mode, because the Auto Mode causes the camera to adjust the brightness and parameters like speed, ISO etc individually for each image. This could result in perceptible difference in color and brightness between the photos which would produce a very bad result when stitched. Instead, manually set these parameters like speed, aperture and ISO and use the same settings for each shot.




Various shots of the Great Pyramid




The final Great image of the Great Pyramid


Now comes the stitching part. This is easy, since the software called AutoStitch will take care of it. Start the application and click Edit>Options and set the Scale to 100%. Now load the pictures into AutoStitch (the program supports only JPEG format) and the program will automatically identify the correct sequence and merge it to create one huge image. Crop the image to remove the edge which bears signs of the stitching operation and your poster is ready to print. You can perform some post processing in Photoshop or other image editing software to adjust the colors, contrast etc before printing.