codec - Is re-encoding JPEG images an idempotent operation? -



codec - Is re-encoding JPEG images an idempotent operation? -

i aware jpeg compression lossy. have 2 questions:

given operation t: 1. take jpeg-80 image 2. decode byte buffer 3. encode given byte buffer jpeg-80

is t idempotent operation in terms of visual quality? or quality of image maintain degrading repeat t? same hold true jpeg-xr codec?

thank you!

edit: since there have been conflicting answers, great if provide references!

by definition, lossy operation discards info simplifying representation in way (ideally) isn't noticeable end user. however, encoder has no magic method determining pixels of import , aren't, encodes pixels equally, if artifacts!

in other words, encoder treat lossily-compressed image same lossless image. lossy image farther simplified, discarding additional info in process, because encoder knows, user intends represent artifacts.

here examples of jpeg generation loss:

http://vimeo.com/3750507

http://en.wikipedia.org/wiki/file:jpeg_generarion_loss_rotating_90_(stitch_of_0,100,200,500,900,2000_times).png

jpeg codec jpeg-xr

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