PDFs that need to lose weight

Sep 22

The cost of hard-drive space has dramatically decreased throughout the years, but the amount of data being created is keeping up. It’s important to find ways to manage the space you have and one way to do that is to consider file compression. PDF files are a great opportunity most times to save space. PDFs consist of layers. If you have a PDF converted using OCR it will most likely have an image and text layer. There are several ways to consider compressing PDFs either during scan, post scan, or a compressed file format.

Compressing PDFs during scan is the fastest way to ensure files are in the size you expect. The downside is that you never start with an uncompressed file so quality is out of your control. Most advanced compression tools are not lossless so the file can be compromised, if you don’t ever have a chance to view the file uncompressed there is no chance for undoing any issues. The during scan compression essentially compresses the TIFF or RAW image file prior to PDF creation so the other downside is that it’s not the highest compression that can be achieved.

Compressing PDFs after scan allows you to leverage the latest technology, and ensure greatest compression. There are tools that instead of compressing an image before PDF creation, that will work specifically on a PDF format. The benefit of this is that they can leverage tools specifically within the PDF to create a compressed file. This usually results in the smallest file format with the greatest residual quality.

The most common tool for compression is a compressed file format such as RAR, ZIP, etc. These tools have the ability to very nicely compress many formats into a single file. The challenge is that for files that need to be viewed regularly it requires a step of un-compression. This is time consuming and increases the risk of file loss. This type of compression is useful for storing files that are not regularly accessed. Because it can compress many formats, it is not as advanced in any one format as specialized file compression tools are.

People commonly overlook the importance of compression. Because compressed files often replace originals you only have one chance to get it right for the life of that file. Companies will use various forms of compression. Because PDF files usually contain important information please consider heavily how you wish to store and compress them.

Chris Riley – About

Find much more about document technologies at www.cvisiontech.com.

Don’t over clean – the effects of image clean-up on accuracy

Dec 06

There is always some way to modify a scanned image to improve its recognition results if it’s not already perfect. But there are also ways to modify an image to destroy recognition results. Not all image cleanup is good for OCR for several reasons.

There are two types of image clean-up. First is image clean-up for view-ability. These are the image clean-up tricks that make images look even prettier on the screen where the goal is what is called pixel perfect where the image looks like it was electronically generated. The second is image clean-up for OCR or Data Capture. These are the tricks to making the image gain better recognition results. All image clean-up for OCR and Data Capture is good for view-ability, but not all image clean-up for view-ability is good for recognition. The reason for this is that engines were built and trained during a time where many image clean-up technologies were not available, and because recognition technologies interpret pixels, it’s possible to remove useful ones.

Here are some tips. Stick to certain types of clean-up for recognition when this is the primary purpose. Some products and scanners will even allow what is called “dual stream” where one scanned image produces two results that can go separate paths. If you have this function, use settings for one of the images that are best for OCR and settings for the other that are best for view-ability. Good for OCR is:

1.)Despeckle ( unless dot-matrix font )
2.)Line Straightening
3.)Basic Thresholding
4.)Background removal
5.)Correction of Linear Distortion
7.)Line Removal ( sometimes )

Bad for OCR is:

1.)Adaptive Thresholding: Often causes a condition called “Fuzzy Characters”. “c”’s will be “e”’s. For hand-print you often remove portions of characters.
2.)Character Regeneration: Removes critical information important to OCR and ICR processes. If you use it in OCR ( Machine-Print ) you will notice more “high confidence blanks”, the characters are so perfect they look like images to the OCR engine and are ignored. In ICR ( Hand-Print ) you will damage the hand stroke of the characters thus confusing the ICR algorithms and reducing trainings ability to understand the subject and this ultimately reduces accuracy.
3.)Line Removal: Bad line removal makes bad OCR. Line fragments really interfere with OCR and ICR processes.

When using imaging for OCR and Data Capture processes, consider only those that improve the recognition rates, not destroy them.

Chris Riley – About

Find much more about document technologies at www.cvisiontech.com.