Scanning And Image Processing
Background Information on the Production of the Images used in the Apollo (Handheld/Still) Imagery Catalog
This catalog was created using a set of images received from the NASA Johnson Space Center. The images were created as follows:
- The Apollo film was scanned using a video camera, with a resolution of over 700 lines, to create a digital file.
- Each frame was digitized as a 24 bit color image at 756 x 486 pixels, producing a file of approximately 1.1 megabytes in Targa format.
- The Targa images were then processed to produce a 640 x 480 image at 72 ppi in JPEG (JPG) format. These images were also (significantly) compressed, reducing the final file size to about 40 kilobytes on average.
These images were further processed by the LPI as follows:
- They were cropped to match the original proportions of the image on the original film. This also had the effect of removing some of the curved edges introduced in the original scanning process.
- The images then received some "color" processing. This was done because the aging of the film had altered the original colors captured when the film was exposed. In the case of the images on black and white film, the "color shifting" was removed by grayscaling the images. For the images on color film, a generic color processing formula, arrived at by tweaking representative images by hand, was applied in an attempt to shift them back closer to their original colors.
- The resulting images were then saved again in JPEG format, with a small amount of compression, at 450 x 450 pixels to create the browse images and at 120 x 120 pixels to create the thumbnail images used in the catalog.
Because of all this processing, these catalog images should not be used for research purposes. They should only be used to select and identify images for use in a research project. Higher resolution products should be obtained for use in any scientific investigation(s).