ImagXpress 13 for ActiveX - User Guide > How To > Reduce a PNG Image |
Use the PNGReduceFile and PNGReduceData methods to losslessly reduce PNGs in memory or on disk without first decompressing to a DIB, thereby saving processor time and system resources.
Supports 1, 4, 8, 16, and 24-bpp PNGs. |
File size reduction is accomplished by removing select pieces of metadata and other possible color and/or transparency reductions of the source PNG.
Compression ratios will vary depending on the source PNG. For example, applying either PNGReduceFile or PNGReduceData to a 1280x960, 24-bit color PNG reduces its size from 1754 KB to 1377 KB. However, applying either PNGReduceFile or PNGReduceData to the output PNG results in no further size improvements.
To reduce PNGs on disk, just specify the path to the source PNG and the path to save the re-compressed PNG using the PNGReduceFile method.
To reduce PNGs expressed in memory, first read the source PNG data into the variant and then re-compress the PNG data using the PNGReduceData method.