[ Contents |
Digital Frontiers ]
HVS Animator contains a palette reduction algorithm that uses the power of Human Visual Systems technology to retain image quality even at low color counts. This feature allows you to reduce the current global palette to a specified bit depth and/or a custom number of colors. The number of colors used in the current (unreduced) animation is diplayed in the title bar of the main Preview.
After opening or importing, HVS Animator analyzes the frames and automatically determines the lowest recommended color count, which is displayed in the "Min colors:" field above the "Auto reduce" button. This value is automatically set in the "Colors:" field after the animation is opened. Thus, if you open an animation and click on the "View reduction" button, you will immediately see what the animation looks like at the lowest recommended color count.
Selecting a different bit depth will automatically calculate the corresponding number of colors and display this value in the "Colors:" field. Likewise, choosing an exact number of colors will automatically calculate the corresponding bit depth.
Because of the way GIF compression works, you will find that the most significant size gains occur when you reduce colors to the next lower power of 2 (8,16,32,64 or 128 colors). Intermediate values are useful for tuning, but the powers of 2 are a good starting point. The bit depth choice box provides an easy way to get powers of two.
The reduction editor behaves in a manner identical to the dither, offset and delay editors. To begin editing, click on the editor panel. This will raise the panel to indicate that edit mode is on. If not in edit mode, dragging the mouse up or down will increment or decrement the value in the panel, respectively. The amount of the increment or decrement will be determined by the velocity of the mouse drag. Once you've entered edit mode, you can also change the value by pressing the "+" or "-" key, or by simply typing in a new value. You can also select characters by dragging with the mouse when in edit mode.
Once you have chosen the desired reduction settings, you can change the dither strength to use for the reduction by using the dither editor. To perform the reduction, click the "View reduction" button. A preview of the animation with the specified reduction and dither setting will be created. If you are happy with the results, chose an optional optimization setting* and click "Save". If not, try reducing to a different bit depth or number of colors, or use the "Auto reduce" button to display reductions to a range of recommended color counts.
The palette reduction feature will not alter the RGB values of colors that it chooses in the reduced palette from their original values. Thus, if you used Netscape palette colors in the original palette, the new palette will still contain all safe colors, although fewer of them.
If you haven't upgraded to HVS Animator Pro, you will be able to see the results of palette reduction in a preview window, but you will not be able to save the reduced animation.
*This feature is only available in HVS Animator Pro.
