NXPowerLite Technology

Transcription

1 NXPowerLite Technology A detailed look at how File Optimization technology works and exactly how it affects each of the file formats it supports. HOW FILE OPTIMIZATION WORKS Compared with traditional compression, File Optimization takes a different approach to tackling the problem of large files. Its remarkable performance stems from the fact that many large files, such as PDFs and Microsoft Office documents, contain a great deal of hidden bloat that can be stripped away or 'optimized' in order to reduce file size without changing the file format or affecting the visual integrity of the file. File Optimization tackles individual elements inside a document, assessing how to reduce each component in turn. By examining each component in isolation it will choose the most effective method of reduction rather than applying general settings across the whole file. This approach creates much smaller files that remain in the same format, so no readers or decompression tools are required. Compliance File Optimization technology is designed to avoid negatively affecting document compliance obligations. The technology simply makes imperceptible visual trade-offs to reduce file size. The primary focus is ensuring embedded media (photos, graphics etc.) are stored in the documents efficiently while unseen background data is purged from the files. File Optimization sets out to maintain the visual integrity of the content so at all times optimized files should be indistinguishable from the originals by the human eye. We encourage you to check the compliance requirements of your industry carefully and if there is any need for further clarification on what File Optimization does to files do get in touch. Before rolling out NXPowerLite, I ran it past the council s legal team and there have been no compliance issues with using the software. Physically, the results look exactly the same to the naked eye something that is critical when dealing with court documents. Neil Harvey, Server Support and Development Officer for Caerphilly County Council PDF Compression PDF files are most often scanned physical documents or documents that have been created entirely digitally often referred to as 'native' or 'born digital' PDFs. NXPowerLite is able to reduce the size of both

2 types of PDF by resizing images, adjusting image formats and quality levels while removing background or hidden data that isn't needed for normal use of the file. SCANNED PDF FILES Scanners often capture document pages as high resolution images without compression. So even documents that appear to be just text can often be entirely images. By reducing the resolution of these images and choosing an efficient image encoding these files can be dramatically reduced. NATIVE PDF FILES PDF files generated from an electronic source - such as a Word document, a computer generated report, or spreadsheet data - will usually be formed of a combination of text and images. For this type of file NXPowerLite ignores the text and focuses on resizing and choosing the best format for the embedded images. COMPARISON Description File size Reduction File link

3 Original scanned PDF 9 MB 0% Download Optimized scanned PDF 2 MB 78% Download Original native PDF 8.3 MB 0% Download Optimized native PDF 1.9 MB 77% Download HOW IT WORKS RESIZES IMAGES Images are often inserted into PDF files at much larger sizes than necessary. For example, a photograph taken by a digital camera might contain five million or more pixels, but most of this detail will not be visible unless 'zoom' controls are used. NXPowerLite can scale these images down to target a particular resolution for display or print. CONVERTS IMAGES TO MORE EFFICIENT FORMATS PDF files allow a wide range of inefficient image formats to be stored inside them natively. NXPowerLite converts bi-level (black and white) images to lossless JBIG2 encoding, which typically generates files one third to one fifth the size of CCITT Group 4 encoding. NXPowerLite also converts many other image types to JPEG where appropriate. ADJUSTS THE JPEG QUALITY OF IMAGES NXPowerLite can also apply additional compression to images that are already in the JPEG format. This can squeeze out impressive additional savings without noticeable loss of quality, even at 100% zoom. REMOVES PRIVATE APPLICATION DATA Applications that create PDF files, such as Adobe Photoshop or Acrobat, can store information within a PDF for use when editing the file. This information can only be used by the application which created the file and is not needed to display the PDF. For most cases we recommend deleting this data, as it will have no effect on the use of the PDF file. A unique file optimization solution that eliminates unessential data, converts graphics to the most efficient format and resolution, dramatically reduces the size of content-rich files, and increases efficiency and bottom line cost savings, all while keeping the file basically intact. JPEG Compression Terri McClure, Senior Analyst, Enterprise Strategy Group Most JPEG images are produced by digital cameras, which are optimized to preserve as much information as possible in order to allow the image to be edited and post-processed. Most of this information is not visually detectable and unnecessarily increases the size of the file. NXPowerLite uses a number of

4 techniques to reduce the amount of data in JPEG files, resulting in impressive size reduction without discernible loss of quality. NXPOWERLITE CAN REDUCE THE FILE SIZE OF YOUR JPEG PHOTOS BY MORE THAN 50% WITHOUT RESIZING THEM. We decode and then re-encode JPEGs using more efficient settings. This allows us to substantially reduce the file size without reducing the image resolution and without changing the perceptual quality of the image. The lossy compression approach we use does create slight pixel differences in the before and after file. If you analyze the uncompressed and compressed images with a computer using a threshold algorithm, you can see minor differences but by eye, they look identical. PRINTING OPTIMIZED IMAGES Image resolution is the main factor when considering how images will print - if the resolution is too low then it negatively affects the print quality. Because NXPowerLite doesn't change the image resolution you can be comfortable that images on your network will still look great when printed.

5 COMPARISON Description File size Reduction Resolution File link Original image 5.5 MB 0% 3744 x 5616 Download Optimized image (quality 9) 4.4 MB 20% 3744 x 5616 Download Optimized image (quality 8) 2.3 MB 58% 3744 x 5616 Download Optimized image (quality 7) 1.6 MB 71% 3744 x 5616 Download HOW IT WORKS Where appropriate, NXPowerLite applies additional JPEG compression to images. The default setting (8) will result in an undetectable loss of quality, even at 100% zoom or when printed. NXPowerLite uses a number of additional techniques to reduce the amount of data in JPEG files, resulting in impressive size reduction without any discernible loss of quality. These techniques include optimized Huffman coding and Chroma subsampling. Note: By default JPEG images are not resized as part of the optimization process and EXIF metadata is preserved. Microsoft Office Compression Microsoft Office files contain an abundance of content that can be optimized; from oversized images and old fast save information to hidden data in embedded objects. NXPowerLite can selectively optimize each of these elements within the files to create leaner, smaller documents, spreadsheets and presentations. IMAGE RESIZING Images are often inserted into Microsoft Office documents at much larger sizes than necessary. For example, a photograph taken by a digital camera might contain five million or more pixels, but most of

6 this detail will not be visible unless zoom controls are used. NXPowerLite can scale down such images by a configurable amount. For example, if NXPowerLite is configured to optimize PowerPoint files for viewing at 1600x1200 pixels (the default setting), any images which fill an entire slide and are larger than 1600x1200 pixels will be scaled down to 1600x1200 pixels (sufficient for nearly all viewing and printing purposes). Note: Resizing can be enabled or disabled and specific resolutions configured in the Image Optimization tab of the Settings dialog JPEG CONVERSION & COMPRESSION NXPowerLite can convert certain types of image to JPEG format, which offers high compression levels but can affect image quality. NXPowerLite can also apply additional compression to images that are already in the JPEG format. The default setting (7) will result in a barely noticeable loss of quality, even at 100% zoom. Note: JPEG compression/quality level can be configured in the Image Optimization tab of the Settings dialog METAFILE CONVERSION Microsoft Office documents often contain images in WMF ( Windows Metafile ) and EMF ( Enhanced Metafile ) formats, which are suitable for vector graphics but are highly inefficient for representing bitmapped images (e.g. screenshots or photographs). Wherever possible, NXPowerLite will convert such images to PNG or JPEG format. REMOVES "FAST SAVE" INFORMATION PowerPoint 2003 and earlier have the option to enable 'Fast saves'. This has the effect that in some cases, deleted or edited objects will not be removed from the PowerPoint file when changes are saved. NXPowerLite removes this 'fast save' information, preserving only the most recent edit. Previous edits are not available through PowerPoint s user interface anyway, but forensic tools may be able to extract some historical information from a fast saved file. REMOVES UNNECESSARY METADATA Some image file formats (e.g. PNG or JPEG) allow additional metadata to be embedded in the image file. For example, JPEG files created by a digital camera may contain EXIF information which indicates the type of camera used, where the photograph was shot and date that it was taken. NXPowerLite removes any data which is not required to display the image. REMOVES CROPPED AREAS OF INSERTED IMAGES After inserting an image into a Microsoft Office document, it is possible to request that the image be 'cropped'. This option is available by right-clicking on an image and selecting 'Size and Position...' in Office 2007 or later, or 'Format Picture...' in earlier versions of Office. Cropping causes only part of the image to be displayed, although the entire image is preserved when the file is saved, so it is possible to undo or change the amount of cropping later. If NXPowerLite is configured to discard cropped image data, the non-visible parts of images will be removed, so will not be recoverable after optimization.

7 Note: Removing cropped areas of images can be enabled or disabled or set to occur in files that haven t been modified within a specified timeframe. This is configured in the Hidden Content tab of the Settings dialog. FLATTENS EMBEDDED OBJECTS Embedded objects (e.g. an Excel chart embedded in a PowerPoint presentation) are saved in Microsoft Office documents with two representations - a 'picture' representation and a 'native' representation. If NXPowerLite is configured to flatten embedded objects, it will remove the 'native' representation, which can significantly reduce the size of files, but flattened objects can no longer be edited in the application in which they were created. Note: Flattening embedded objects can be enabled or disabled or set to occur in files that haven t been modified within a specified timeframe. This is configured in the Hidden Content tab of the Settings dialog. TIFF Compression* NXPowerLite can shrink uncompressed TIFF images by applying lossless LZW compression. As this builtin compression method for TIFF files is lossless it's a great opportunity to reclaim server space. Many TIFF files are stored uncompressed despite the file format having a number of lossless compression methods built in. This results in much larger file sizes, with the only benefit being slightly faster opening times.

8 LOSSLESS LZW COMPRESSION NXPowerLite can now identify TIFF files that are stored uncompressed, and will apply lossless LZW compression to them. As an example of how this works, you can see the uncompressed TIFF image below being reduced from over 29 MB down to just below 13 MB by applying LZW compression: * TIFF compression only currently available in NXPowerLite for File Servers Happy to help The information above explains exactly what our technology does to each file type. With it we hope you'll be able to make an informed choice about using our software. Please contact us if you have any questions we haven't covered and we'll be happy to help.