MacDraw Pro: Gradients Become Banded or Undithered

When enlarging a large gradient-filled object, the display of the gradient may lose its dithering. The gradient will appear with noticeable bands of color, without dithering. This effects screen display only, not the quality of printing. This only occurs when the video is set to 256 colors or less.

Increase the memory for MacDraw Pro, or switch to 24/32-bit video mode (millions of colors). Additional workaround: see explanation below.

Gradients are defined in MacDraw Pro using 32-bit QuickDraw, even though the monitor may be set to display fewer colors, such as 256. In this way, gradients can be printed in the highest possible quality regardless of the number of colors that can be displayed on screen. When displaying gradients on a color screen set to 256 colors or less, MacDraw Pro dithers the colors in the gradients. This dithering results in a gradient with smoother looking color transitions (without noticeable bands of colors). The gradient may be displayed using only the 256 available colors, but the dithering gives the appearance of more colors.

A large gradient-filled object requires lots of RAM. For example, a full-screen rectangle with a gradient displayed on a 13-inch color monitor may use about a megabyte of memory. Increasing the size of a gradient-filled object increases the RAM used. If you increase the size of a gradient-filled object, MacDraw Pro may run low on available RAM. When this happens, MacDraw Pro will switch to displaying the gradient in Fast Display mode to conserve RAM (no dithering).

The RAM used to display gradients in high quality is not shown in the memory usage indicator in the About MacDraw Pro window. Thus, even though this indicator may show that there is a megabyte or more of available memory, MacDraw Pro may be using most or all of this memory for things like displaying gradients in high quality.

TIP: When a gradient is displayed using the Fast Display mode, MacDraw Pro uses the colors defined in the current color palette to display the gradient. If the current color palette contains few intermediate colors between the 2-4 colors that define the gradient, MacDraw Pro will have few colors to display the gradient. Thus, the gradient may display with only a few very wide bands of color, instead of many smaller bands of colors.

If you add colors to the current palette that are intermediate to the colors in the gradient definition, MacDraw Pro will display the undithered gradient with more colors. Thus, you can make the undithered gradient display quality better. You can create these intermediate colors by creating colors that are a blend of the colors in the gradient definition. You can then place all the colors (the gradient colors and the intermediate blended colors) in the Style Bar. This way, if the total colors in the Color Palette and Style Bar exceeds the number of colors that your video card can display, these colors will be given priority for being displayed as solid colors.