Jaggy character display

Description:

If characters are displayed jaggy instead of a smooth shape, it can have several reasons. Before you contact the EmWi support or searching the problem in your EmWi project, you should ensure that the jagged characters are not due any video post-prosessing such as scaling or disadvantageous video improvements.

Solution:

1. Index8 color format

First of all considerations we should have a look on the used color format. In Index8 platforms, jagged characters are often caused by a combination of a disadvantageous CLUT and the selected font quality (see attribute ‘Quality’ in your Font resource brick). Since Index8 is a low quality color format it is hard to find a good trade-off between a good font quality and the usage of anti-aliasing of different font colors on different background colors. To reach this you need to take care that the necessary colors for anti-aliasing are available in your CLUT. This can either be done, by a manual editing of the used CLUT file (see attribute ‘Clut’ in your profile) or with the latest feature level EmWi offers an automatic CLUT generation. Please have a look in the HowTo document HT-010-GenPalette.pdf for a guided tour for manual and automatic CLUT generation.

2. Font quality

The font quality is an attribute of the type Resources::Font and can be set to ‘Low’, ‘Medium’ or ‘High’. ‘Low’ font quality will cause EmWi to generate 1-bit based bitmap font from the used true type font glyphs without anti-aliasing. ‘Medium’ font quality will cause EmWi to generate a 2-bit (4 colors) based bitmap font and ‘High’ font quality generates a 4-bit (16 colors) based bitmap font. Higher font quality improves the readability of the glyphs by anti-aliasing, but you must be aware that it raises the memory requirement of the font resources.

See also:

HowTo document [HT-010-GenPalette.pdf]

Keywords:

Font, quality, CLUT, display, anti-aliasing, jaggy, character, glyph, scaler, video processing, color format