Posts Tagged ‘lossless’

JPEG Standard Gets a Boost, Supports 12-Bit Color Depth and Lossless Compression

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The JPEG standard made its debut in 1991 (publicly in 1992), and since then it’s become the most widely used lossy compression format for digital images. Now, The Independent JPEG Group at the Leipzig Institute for Applied Informatics — the folks responsible for defining the standard — has released an all new version 9.1 of the software library that comes with some powerful new abilities. Read more…

Using Romeo and Juliet to Illustrate the Pitfalls of JPEG Compression

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It’s common knowledge that JPEG compression leads to a loss of data, but it’s difficult to really visualize the extent of that loss in a photo. A keen eye will be able to tell a difference, but it’s still hard to quantify it.

Tom Scott wanted to bring the reality home to those who don’t already understand it. So he took the pitfalls of JPEG compression and transferred them from the world of photos, to the world of Shakespeare. Read more…

Why You Should Always Rotate Original JPEG Photos Losslessly

Recognize the warning message above? It’s what Windows XP would show whenever you tried to rotate a JPEG image 90° using the Windows Picture and Fax Viewer. If you’re like me, you probably didn’t think twice about it (and checked the checkbox), since you had done it many times already and hadn’t noticed any difference in quality. After all, how hard can it be to turn a digital photo sideways? You just move the pixels around right?

Well, not really. The fact of the matter is, JPEG is a “lossy” compression algorithm that’s geared towards storing and sharing photos without taking up too much disk space. Rotating these compressed images is usually done by decompressing, rotating, and then re-compressing. Since the re-compression is lossy (i.e. data is thrown away), this process results in slightly degraded photos (hence that warning).
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