6.14.4 Limiting bitmap resolution and color depth
Graphics destined for print look best at a resolution of 300 to 1,200 DPI. However, you cannot use FrameMaker to increase the DPI of an existing bitmap image: the upper limit of resolution is the DPI of the original graphic.
Use 256-color (8-bit) BMP images where possible
The number of colors in bitmap images should be 256 or less, because the size increase for more colors can make files too large for Word to load. If you use 24-bit color, conversion can be slower and the resulting .rtf files much larger. This is because Mif2Go has to use embedded WMFs to get the images into Word, and 24-bit bitmaps do not compress in WMFs. If you are using 256 colors (8-bit bitmaps), conversion is faster and output file size smaller. However, reducing a photographic image to 256 colors degrades its appearance.
Save Word files with 24-bit BMP images as .doc
RTF lacks compression for 24-bit BMP images (which include “millions of colors”). Every pixel takes 3 bytes. At 300 DPI for acceptable print quality, a 3.25" x 3.5" image would contain 1,023,750 pixels, requiring about 3 MB in a binary format. However, because RTF represents each byte with two hexadecimal digits, the actual size would be 6 MB. On the other hand, if you are able to load an RTF file containing such an image into Word, you can save the file as a Word .doc file. Then Microsoft uses a proprietary compression method to shrink the size drastically. Unfortunately, Mif2Go cannot legally use this method, thanks to the Digital Millennium Copyright Act (DMCA).
§31.2.1.2 Converting bitmap graphics for print RTF
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