Posts Tagged ‘JBIG2’

Which bitmap format to choose

Hi folks,

Following the short suite of articles that briefly described the most popular raster graphics file formats, today we will try to make a synthesis and see which format would be a best choice for which purpose.

Image capturing
When capturing images, either by scanning a document or taking a photo, the best idea would probably be to get the highest quality possible and keep the full amount of details.
The initial capture file is a “master” file so, unless you can repeat the same capture process anytime or don’t care about long term preservation, you can store it somewhere safe and convert it to other formats for current manipulation.
And if you think that such practice is for professionals only, you’d better think again.
IT evolves at highest speed: image acquiring quality is increasing, bandwidths are getting larger and cheaper, storage spaces too and image quality standards are adapting accordingly so what was considered a professional level of quality few years ago, today is widely common.
So you shouldn’t be afraid to use TIFF format as best choice for richest captures.
But there’s always PNG at disposal too of course.

Image handling
Chosing a format for image handling depends mainly on the kind of image involved but also on its manipulation purpose.
For example, JPEG is notoriously the best choice for photos offering an optimum quality vs. size ratio, we’ve explained you previously how this was achieved.
JPEG can be used especially for smooth-toned images but due to its small sizes, even if quality-lossy, it can be used for any kind of images including documents.
Actually, when it comes to documents to be shared at real minimal size with least acceptable quality, there is JBIG2.
Making a visual comparison between a JPEG and a JBIG2 format version of a same document might seem to turn JPEG into a winner.
But for large amounts of documents or for transfering documents through busy networks, JBIG2 is a life-saviour.
In case the quality of the document is really important, PNG should do the trick.
For web graphics, GIF and PNG are largely prefered.
They both are palette-based and the file-sizes depend on bit depth and on the number of colors of the palette, one basic difference being that GIF allows animations while PNG supports gradual transparency.
So they both are well-suited for webdesign items like logos, buttons, banners and so forth, the choice depending on graphic artist’s intentions.
For short animations (today used mostly for tutorial/explanatory purposes) GIF is the only choice, similar to how PNG is the only choice for graphics where variable transparency is required.
As you’ve probably noticed, we’ve mentioned PNG several times above as it can be used for full-colour images with lossless compression, continuous-tone full-colour images at the highest quality (not highest compression), B/W and greyscale images, for desktop and web purposes, thus making PNG a reliable and versatile quick choice solution when there is no real pressure for a certain requirement.

Image printing
Normal printers are designed to work fairly well with all kind of image file formats.
But if printing quality is a serious requirement (talking about desktop printing quality level, not highly professional level) then the “give me most possible data from uncompressed source and I’ll give you best possible result” principle applies.
In other words: use TIFF.
Which is yet another reason for you to consider the initial recommendation above of keeping “master” files.

Well, the circle being closed now, let’s just add that we’ve tried to keep everything as basic as possible.
There are many aspects and details we’ve intentionally skipped because the scope of our blog articles is simplicity.
But if complexity is what you need, please feel free to use GdPicture.NET SDK to build applications controling every possible detail of images in more than 90 supported file formats.
And if you’re not into software development, have no worries: we’ve already built such application for you.
It is called PaperScan and it can be downloaded from here.

See you next week, folks!

Bogdan

Big Browser on August 23

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About JBIG2 compression

Hello folks,

Although disk storage and internet connection bandwidth are constantly increasing and getting cheaper, worldwide efforts for better file compression are increasing as well.
This is no paradox and there are too many reasons for this to mention but we all know that, for instance, file transfers are never fast enough.

For document imaging domain there is JBIG2 compression scheme.

Learn more ...