Grafika:JPEG JFIF and 2000 Comparison.png

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Rozmiar podglądu: 642 × 599 pikseli
Obraz w wyższej rozdzielczości‎ (720 × 672 pikseli, rozmiar pliku: 550 kB, typ MIME: image/png)

Plik JPEG JFIF and 2000 Comparison.png [ edytuj opis ] umieszczony jest w Wikimedia Commons, repozytorium wolnych zasobów projektów Fundacji Wikimedia. Wyjaśnienie podanej poniżej licencji znajdziesz na stronie Opisy licencji grafiki.

[edit] Summary

This image is a PNG for a comparison between JPEG (plain, JFIF) and JPEG 2000. I (Shlomi Tal) cut a chunk of the photo (576×224 out of the original 1024×768, to be exact) with the GIMP, then saved to PPM. I then generated a JPEG version of it with a quality of 30 (on the IJG scale), yielding a file size of 11,502 bytes, computed as approximately 1/33.65 of the size of the uncompressed image. After that, I generated a JPEG 2000 version with a compression ratio of 1:33.65, yielding a size of 11,406 bytes. Finally I converted both images to PPM, created the captions (144×224 each) for the three images, stitched them all into one image and converted them to PNG with 0.45455 gamma. With pngcrush I added the text chunks and optimised the file.

I chose quality 30 because compression artifacts are guaranteed at that compression level. The reference uncompressed image is from my camera in lossless mode. The PNG is not interlaced, for I deem interlacing fit only for critical images (such as image maps for navigation) or previewing (which on Wikimedia is taken care of by the thumbnails).

[edit] Licensing

I, the copyright holder of this work, hereby publish it under the following licenses:

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation license, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation license".

This file is licensed under the Creative Commons Attribution ShareAlike license versions 2.5, 2.0, and 1.0

You may select the license of your choice.

Historia pliku

Kliknij na datę/czas, aby zobaczyć, jak plik wyglądał w tym czasie.

	Data/czas	Wymiary	Użytkownik	Opis
aktualny	05:18, 19 sty 2008	720×672 (550 kB)	CountingPine	(Losslessly reduce file size)
	20:40, 24 cze 2006	720×672 (571 kB)	Shlomital	(Comparison image for JPEG and JPEG 2000)