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PGY 4440C PHOTO COMPUTER IMAGING
THE RIGHT COMPRESSION | Which method and when?
Even before taking the photo, and also before saving the image data again on the computer, you should have a clear idea of what the images are to be used for. In case of doubt, you have no alternative but to choose a memory-gobbling format, so as not to rule out any particular use from the outset.
TIFF
You're on the safe side if, provided the camera offers it, you give preference to a non-compressing method, as this passes the image data to the storage medium in the way it was captured by the chip.
The TIFF format preserves all the image information during saving, making it the method of choice when large-format photos or posters are to be printed, or if you are planning on making selective enlargements, for instance because you don't have or can't use a telephoto lens when taking the shot. Lossless LZW compression is a good choice for image editing, while the ZIP format will additionally reduce the size of the file if you want to send it off in an e-mail.
JPEG
With the JPEG format and a powerful compression program or image editing software, you have every opportunity to compress an image for virtually any conceivable purpose. However, you always have to keep an eye on the reciprocal effect of file size and accuracy of detail. If you compress too much too soon, without retaining the original file, you will irretrievably lose the data.
GIF
The GIF format is ideal for compressing graphics and graphic-like images characterized by sharply defined, relatively uniform areas of color, like some comics. It is always suitable for halftone images if you want not only a high degree of compression, but also plan to integrate text into the photos or animate the images for use on the Internet. The GIF format is usually also superior to the JPEG format in terms of quality and file size when it comes to navigation buttons on websites or graphic logos.
PNG
The PNG format, especially the 8-bit version, can be regarded as a good alternative to the GIF format, as it permits smaller file sizes with identical image quality under certain circumstances. However, you should note that, being a rather exotic program, it cannot be read by every program and, if used on the Internet, cannot be reproduced by every browser.
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