Timothy
Parker Consulting Incorporated
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LizardTech’s MrSID Digital images take up huge chunks of disk space and seldom
compress much. When you want to
offer high-resolution images from a Web server, you need a lot of bandwidth and
a lot of disk space. LizardTech’s MrSID hopes to solve both problems and allow
high-resolution images to be stored in less space on your drives, and download
faster. MrSID relies on a compression technology that LizardTech
has patented, called the MrSID Imaging Language. The MrSID Image Server takes
care of compressing and serving up the images.
The Image Server allows most images to be handled, as well as offering
capabilities like panning and zooming an image. In order for a visitor to take
full advantage of MrSID images and control print output, a free on-line viewer
integrates with either Internet Explorer or Netscape Navigator. The viewer adds
a new toolbar to the browser and a new pop-up menu. The viewer is not necessary
for a visitor to view the encoded images in their browser. MrSID installs easily enough. An InstallShield wizard takes
care of the installation for you on any Windows platform with 5MB disk space and
a minimum of 32MB RAM. MrSID can handle bitmap, JPEG and TIFF images (but no
other formats). The software supports RGB and CMYK images, as well as grayscale. Adding images Processing images with MrSID is accomplished through the
single dialog the software presents. Use
the Add button to compile a list of all the images you want to encode, make sure
the output directory is correct, and then click the Encode button.
The slider on the MrSID dialog lets you adjust the compression ratio from
its default setting of 20:1. The compression ratio has a relatively minor effect
on the quality of the image, but more importantly allows you to adjust the
compression to the filesize you need. The
more compression, the more processing MrSID has to do to unpack the image. A
small progress bar at the bottom of the dialog keeps you informed of the amount
of time left when compressing images. The
encoding process is quite quick, even with large files. To view an encoded file,
you need only double-click on the filename to launch the viewer in a browser. The ability to zoom and print a portion of an image from
your Web browser turned out to be handy, especially when we used MrSID to create
a set of on-line assembly instruction pages for customer download (the original
high-resolution filesizes of the ten images was 2GB and MrSID compressed them
all to 120MB). The software allowed
a portion of each page to be zoomed and then printed with very good quality (of
course the final output quality depends on your printer). MrSID works quickly
when accessed through a Web server. Downloading
a .tiff file that was 7MB big took a lot less time encoded to a filesize of
330kB! Limitations Despite LizardTech’s claim of no image artifacts
resulting from the encoding process, we did experience some pixelation effects
on large files with fine details, such as resolution patterns. That being said,
though, MrSID did a very good job of handling zooming by smoothing the edges and
reducing pixelation to a minimum. The software worked flawlessly in testing with
no crashes or other aberrations. There are a few limitations to this release of MrSID.
First, support for .jpg and .tiff files is handy, but some other file
formats would also be useful. Second,
the maximum image size that can be handled is 2100x1600 pixels.
While this is adequate for many digital photos, megapixel units like the
Nikon D1 or slide scanners can produce images of higher pixel counts. Any image larger than 2100x1600 causes an error in MrSID.
Once MrSID has encoded an image, it cannot be un-encoded. The free viewer will allow you to save an image as a .tiff
file, but a comparison of an original .tiff and an un-encoded, generated .tiff
file shows quality degradations. So don’t delete your original files! Wrapup Although LizardTech aims MrSID at Web site users who want to enable downloads of high-resolution images, many readers will find MrSID handy for on-site work, too. Using this software you could compress images to a twentieth (or more) of their size for storage, then expand them with no perceptible delay in a browser. For offering high-resolution images over a Web site, MrSID has no equal. MrSID |
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Send mail to
tparker@tpci.com with
questions or comments about this web site.
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