Products » mBooster » Technical Support » mBooster documentation » Ch3-1-Optimizations » Ch3-1-5-PNG Recompression
PNG Recompression
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Property settings This optimization is turned ON by default. In the property file, OPT.PNG.RECOMPRESSION=ON turns on this optimization OPT.PNG.RECOMPRESSION=OFF turns off this optimization |
PNG Recompression employs Innaworks' superior mBoosterZip compression algorithm to reduce the size of the PNG files. Specifically this optimization recompresses the IDAT data chunks present in PNG files.
By default it removes all unnecessary information from each PNG file, keeping the compulsory chunks and tRNS (transparency) chunk.
By default, PNG Recompression is turned on, as for most MIDlets the time to recompress PNGs is not significant. With mBooster result caching, subsequent mBooster builds will not suffer at all from the time to perform PNG Recompression, as long as the PNG files are unchanged.
The mBoosterPng command-line tool is the equivalent of this step, and can be used separately to mBooster to separate PNG recompression from the normal mBooster execution.
To control the files that will be recompressed by this optimization, and for other configuration options, see this set of properties.
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Be Careful A possible coding practice for J2ME applications is to hard code the size of PNG files into the application itself. When your application is coded to be dependent upon the size of your PNG files, PNG Recompression must be turned OFF, or otherwise the PNG files affected must be explicitly excluded through the PNG.RECOMPRESSION.EXCLUDE property. Using mBoosterPng prior to mBooster and ensuring the application expects the correct size for PNG files is the suggested approach. |