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PNG image variants for mobile content

Companies use Digital Asset Management in censhare to administer all assets they require for content business applications. This allows routine tasks such as the generation of image variants on check-in to be automated. With Version 4.8, censhare creates a variant from a PNG-image, which provides similar quality with only one fifth of the former memory space requirements.

Automation of digital images extended

With Version 4.8, censhare is able to automatically create a much smaller version of PNG images with almost the same quality

censhare's Digital Asset Management is capable of handling a wealth of data. This includes text, images, layouts, video, audio, web pages, product data and mobile content. But censhare also stores all other important data such as templates, time plans and transformations for assets. For a new or modified asset in the system, censhare can automatically create further data. For example, the system generates thumbnails for images, reads out image data in formats like EXIF, processes them or produces a lower resolution copy for the layout. If a print PDF is created, censhare automatically inserts the high resolution version of the image. Or an OPI (Open-Prepress-Interface) system such as Helios takes on the task.

For image processing, censhare is able to generate additional files automatically, with other formats and resolutions. These may be used for web or mobile content. Besides JPEG and GIF, PNG is also widely used. With censhare 4.8, PNG images can be reduced to about a fifth of their original size with almost no loss in quality. The function is also available from censhare 4.7.16.

Customer benefits

  • Automatic generation of a PNG image with considerably lower storage requirement at almost the same quality

Application case

  • Automatic generation of a considerably smaller variant of a PNG image for use in mobile applications

Far lower memory requirements, with almost the same quality

If a user imports an image into censhare or updates it, then other formats are often needed. These may include a preview image, various formats for presentation on the Web such as a title image or photo galleries or display on mobile devices. censhare is able to perform these routine tasks automatically, for instance on check-in. censhare 4.8 includes an additional "PNG with color palette" format for mobile applications.

One line is enough to configure the service for PNG images with color palette

censhare uses the pngquant software library for reducing the size of PNG images. This employs a special algorithm which needs less memory to store the color for each pixel of an image. This means that the image itself takes up significantly less space. The choice of colors is such that the image quality is almost completely maintained.

Instead of the 24 or 32 bits of the original image, the algorithm needs only 8 bits for the colors in the reduced PNG image. The trick is to use a color palette for storing the values. The value for the color of a pixel is no longer a definition of the color, but a pointer into the color palette. This is where the color is defined. The power of the algorithm lies in the choice of colors for the palette, so that the quality remains as close as possible to the original.

Quick setup

In order to use the service for the reduction of PNG images, it must first be set up. The administrator enters the installation path on the server in the area "services" of the configuration for "image". In the "modules" area, under "image", in the configuration "generate additional image file (settings)", the checkbox "indicated colors" must be activated for the format PNG.

The library is available for various Linux versions, Mac OS X and Windows. If the censhare Application Server is running under Solaris, the function may still be used. For this purpose, the censhare service client and the library are installed on one of the systems mentioned. The server then directs the request for the reduction to the client.