Raster Quality Factor Property
The print resolution for raster images is determined by the Raster Quality factory property. Reducing the raster quality factor may be desirable if the print file size is a bigger concern than output quality.
The raster quality factor is the ratio of print raster resolution to print device resolution, specified as a percentage. For example, a raster quality factor of 100% means that raster data should print at device resolution. Setting the raster quality factor to 50% results in raster data being printed at half the device resolution. When printing to PDF at 600 DPI, 50% raster quality means that all images are rescaled to 300 DPI for printing. Large, high-resolution images such as aerial photographs may be scaled down, while small images such as logos may be scaled up.
When printing in rasterized mode, setting the raster quality factor to 100% is a logical choice since all image data eventually ends up at this resolution in the final rasterized print file. However, reducing the raster quality factor yields coarser images after being scaled up to rasterized resolution by the graphics hardware. These coarser images, which may still be of acceptable quality, compress better than the more detailed images produced at 100% quality, and may yield significant reductions in rasterized print file sizes depending on the type of compression used by printer driver.
Before setting the Raster Quality Factor, you should consider the following:
- The Raster Quality Factor has an impact on performance and plot file size.
- Changing the Raster Quality Factor may have a disproportionate effect on printing time and output file size.
- Line art/scanned technical drawings require a higher Raster Quality Factor.
- Use lower Raster Quality Factors for quick draft prints.
- Gray scale or color aerial/satellite imagery may be fully acceptable at a 50% Raster Quality Factor or less depending on the device resolution.