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Photo JPEG





400x200, 20KB per frame, quality 75%
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General Information
Overview
The Photo JPEG codec implements the Joint Photographic Experts Group (JPEG ISO version 9R9) algorithm for image compression. It is generally used for storage of still images. It can also be used for editing and storage of high-quality video files.

There are three JPEG-based codecs built into QuickTime. They are Photo JPEG, MJPEG-A, and MJPEG-B. MJPEG stands for "Motion JPEG," and is indentical to Photo-JPEG except that the MJPEG codecs have translators built-in to support the different capture cards. We will only discuss the Photo-JPEG codec here; MJPEG-A and MJPEG-B have their own section.
Architectures Supported
Pros, Cons & Tips
Pros
  • Picture quality is generally good enough for use in desktop publishing applications.
  • This codec is great for compressing high-resolution, photographic images, and is also very good for 8-bit grayscale images.
  • It works very well for "slide-show" movies that have a very low frame rate.
  • It has some application for Web video, although other commercial codecs are often preferable for most movies.

Cons
  • The Photo-JPEG codec requires significant amounts of CPU power and is not well suited to CD-ROM or higher data rates, except when assisted by a hardware capture card.
  • Large image and/or high frame rate movies usually don't play smoothly.
  • If the same file is saved multiple times, the JPEG artifacts may build up and become objectionable.

Tips

  • If you are delivering a CD-ROM based title which will require a Quadra class system (or faster) to run, you can use the Photo-JPEG-compressed QuickTime movies to store your 24-bit backgrounds to increase performance.
  • Avoid saving the same file multiple times (see above).


Ideal source material Photographs
Supported bit depths 24-bit color, 8-bit greyscale
Compression time Asymmetrical
Temporal compression? No
Special features Supports Media Cleaner Pro 2.0's advanced data rate limiting
Encoder requirements Any MacOS or Windows
Decoder requirements Any MacOS or Windows
Encoder availability Built into QT
Decoder availability Built into QT
Algorithm Discrete Cosine Transform (DCT)
Manufacturer Apple


If you have any comments or tips & tricks to share about Photo-JPEG, please contact us at info@terran-int.com.



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