The PanoramIX authoring tool can be used to combine a set of digital images into a seamless panorama. The digital images my be obtained from a digital camera or from scanning photographic prints. The images may also be created from computer rendering of 3d models and virtual worlds. The following table summarizes the sizes of the files that may be generated by the PanoramIX authoring tool, the amount of physical memory (RAM) needed to avoid thrashing, and a rough estimate of the speed of the resulting stitching process.
The following table was created in 1998. The processor speeds and the amount of memory (RAM) found on personal computers at that time were much less than are available today. Modern personal computers may be used to create panoramas based on high resolution flat images, but users must still be aware of the limits imposed by the physical resources of each computer.
| Quality | Resolution | dpi | TIFF size | JPEG size | Min RAM | Speed |
|---|---|---|---|---|---|---|
| low res | 300x200 | 50 | 1-1.2M | 50k-100k | 8-10M | very fast |
| 320x240 | *** | 1.2-1.5M | 60k-120k | 10-12M | ||
| 384x256 | 64 | 1.5-2M | 75k-150k | 12-16M | fast | |
| 450x300 | 75 | 2-2.5M | 100k-200k | 16-20M | ||
| medium | 600x400 | 100 | 4-5M | 200k-400k | 32-40M | medium |
| 640x480 | *** | 5-8M | 240k-480k | 40-50M | ||
| 768x512 | 128 | 6-8M | 300k-600k | 48-64M | slow | |
| 900x600 | 150 | 8-10M | 500k-1M | 64-80M | ||
| high res | 1200x800 | 200 | 16-20M | 800k-1.6M | 128-160M | very slow |
| 1280x1024 | *** | 20-25M | 1M-2M | 160-200M | ||
| 1536x1024 | 256 | 24-30M | 1.2M-2.4M | 200-240M |
Notes:
- "dpi" values (dots per inch) represent 4x6 scanned photos. Rows with dpi="***" represent low/medium/high resolution images from digital cameras.
- Typical dpi values for screen images = 72 dpi. This includes what you see with web browsers.
- Typical dpi values for scanners = 200 to 300 dpi. This is already too high for most internet applications.
- Typical dpi values for images printed on paper = 300 to 1000+ dpi. (Lesson: do not confuse web browsers with pre-press applications.)
- "TIFF size" indicates a rough estimate of the uncompressed TIFF image files generated by the "Save Panorama" function. TIFF files are a standard file format for storing image files. These typically do not use lossy compression.
- "JPEG size" indicates a rough estimate of the
size of a JPEG file created from the output TIFF file.
- The lossless TIFF file created by the PanoramIX authoring tool may be converted to a JPEG image using any of a wide choice of image processing software titles, including Adobe PhotoShop, Adobe Photo Deluxe, Microsoft Photo Editor, etc.
- JPEG files are usually much smaller than TIFF files because the JPEG files use lossy compression. The amount of image detail which is lost is controlled by a quality parameter. The size of a JPEG file for a particular image is highly variable depending on the content of the image and the value of the JPEG quality factor. The JPEG files sizes shown in this table assume a medium to high quality parameter for the JPEG compression.
- JPEG files larger than around 300k are not practical to deliver to clients over dial-up modems. If the panoramic image is to be presented in a web page, try to keep the image size to under 300k, and add two levels of lower resolution to support progressive resolution at roughly 30k/100k/300k image sizes.
- "Min RAM" is a rough estimate of the amount of physical memory needed to avoid "thrashing", assuming no other applications are being used concurrently. If you lack this amount of RAM, your computer will start madly swapping real and virtual blocks of memory and performance will drop precipitously (10x slower).
- These estimates assume a total of eight overlapping images are being stitched together. A larger number of images will imply proportionately greater RAM and processing time. The sizes of the resulting output TIFF and JPEG files should not change much.
Last modified November 4, 1998.
Last updated January 11, 1999; October 11, 2001; January 27, 2006