jpeg 2000

[arjen van de merwe]

jpeg 2000 gives the possibility of compressing 16 bit images. Are

there other advantages over older jpeg? With old jpeg I can usually

get away with compression 8 for print formats (in case I have to email

an image). Is this roughly the same with jpeg 2000? Does it offer

better image quality or stronger compression?

[emre]

It offers a great lossless compression mode, for one. The lossy one is not a significant improvement over JPEG to most people's eyes. Perhaps this is because the JPEG codebase is much more mature...

[jon_austin]

As Emre Safak has already said, JPEG2000 provides lossless compression. For this reason, I use it to save all of my flattened, edited images. I keep all my original files, and also save a copy to JPEG for quick viewing, as JPEG2000 files load much more slowly.

[bill_tuthill]

I agree with Emre's assessment, but would add that J2K's improvement

for lossy encoding is mostly at the low end of the JPEG scale.

If you mean Photoshop 8, that is pretty low, so yes, you would

probably see improvement with J2K of the same size, assuming anybody

could view the images. There's the rub: most browsers don't support

JPEG2000. And what do you mean "get away with"? Just for e-mailing

pictures to friends? I can't believe a magazine would accept

Photoshop quality 8 for printing.

[brian ball]

you can also save layered images. The compression, lossy or lossless, is quite efficient, at

least compared with making a .zip with a TIFF with Mac OS X. It's great for archiving files and

sending higher quality files over the internet, but both saving and opening these files require

substantial amounts of processing power. Another downside is that many programs cannot

open these files (even on PS CS, you need to manually install the plug-in).

[lex_jenkins]

If you're curious about JPEG 2000 and don't want to spend much or any money right away, download the most current version of Irfanview and its plug-ins. It's a freebie and a very small and fast program. It comes with demo versions of LuraWave conversion tools.

 

After trying it out you can decide whether the extra compression is worth the inconvenience of not being able to view thumbnails with some of the more common viewers such as Windows Explorer.

[oscar_van_der_velde]

I tried the Photoshop plugin from fnordware.com. I did a comparison of JPEG vs. JPEG2000 and found that at 60% quality setting, the JPEG showed some artifacts around sharp edges, but kept detailed structures in clouds and shadows. The JPEG2000 retained sharp edges like the original, at the cost of smoothing out all detail in shadows and sky, and the file was larger as well. Not sure if this relates to JPEG2000 compression in general, or the software used to compress. Lossless gave roughly 2 MB instead of 3 MB file size of the original LZW compressed TIFF.

[sean de merchant httpw]

I think the lossless J2K is great, roughly 1:3 lossless compression.

 

But, for lossy compression it is awful. It tends to generate very ugly boke in an image (highly rectangular and patterned rather than smooth) as the underlying wavelets do not correlate as well with human vision as the DCR underlying JPEG compression does. In short, for photographic images, J2K does not look natural to the eye under heavy to moderate compression. J2K is likely excellent for heavy compression of document imaging (scans of business documents) which is the only thing I have seen it marketed towards.

 

In short, it is slow, but saves lots of disk space for lossless archiving of 16-bit images. It is poor for lossy compression of photographic images.

 

hope this helps,

 

Sean

[rafael_franco]

This is a very objective comparison.

 

http://stefan.winkler.net/Publications/adip2004.pdf

 

Does anyone know if PS CS2 suffers from the same jpeg problem?

 

Thanks

[gordonr]

Jpeg 2000: born 1999(?) much trumpeted, took ill immediately, patented 2001(?) and died soon after. Lamented mostly by those who had no idea of the defects and disadvantages. (Apologies to my mother d:11 Apr 2005).

<p>

In an era of open standards, proprietary software will seldom get more than 10% of the market share. See my article: <a href="http://www.photo.net/learn/jpeg/">http://www.photo.net/learn/jpeg/</a> for more comments.

[bill_tuthill]

If JPEG 2000 lossless does 3:1 compression, that is twice as good as

PNG, which is often around 3:2 (and usually lacks 16-bit support).

Thanks for the URL, Rafael. My favorite line was this:

"Our comparison of JPEG [2000] encoders showed that IrfanView

produces consistently better images than Adobe Photoshop at the

same data rate." I wonder if Irfanview uses the same JP2 libraries

as ImageMagick?

[brendt_wohlberg]

<p style="text-align: justify;">

A significant advantage of JPEG 2000 that has not been mentioned

is its embedded bitstream: an image encoded at some bit rate may

be truncated to give a lower bit rate (i.e. higher compression)

representation. This is very convenient, since, for example, a

high quality image for professional digital imaging may be

truncated to obtain a lower quality image for transmission,

without the need for recoding. Note that this is even possible in

the lossless mode, allowing the full lossless representation to be

truncated to provide an efficient lossy representation.

</p>

<p>

In response to some previous comments:

</p>

<ul>

<li style="text-align: justify;">While there have been some

subjective comparisons suggesting that, within some range of

bitrates, JPEG2000 artifacts are slighly more objectionable than

those for JPEG, referring to JPEG2000 lossy compression as

<em>awful</em> is an exageration. The general consensus is that

(in terms of distortion at a specific bit rate) JPEG2000 is vastly

superior to JPEG at low bit rates, but very similar at the high

bit rates that would be used for high quality digital

photography.</li>

<li style="text-align: justify;">The implication that JPEG2000 is

not an open standard is misleading. While proprietary technology

belonging to a number of companies has been included, an

implementation of the baseline system is free of license fees as

long as it is fully compliant with the standard. There are at

least two open source implementations: <a

href="http://www.ece.uvic.ca/~mdadams/jasper/">Jasper</a>, a C

implementation, used in ImageMagick and many other open source

packages, and <a

href="http://jj2000.epfl.ch/">JJ2000</a>, implemented in Java. </li>

</ul>