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Digital Frontiers ]
The Preview displays either the original RGB image or the reduced image depending on the state of the Preview checkbox. After an image has been reduced, the preview can be toggled between the original and the reduced image by clicking on the Preview checkbox at the corner of the preview, between the scroll bars. NOTE: when the filter is onvoked with non-rectangular selections, transparent and alpha channel unselected regions are displayed in a bright blue color.
You can choose colors for thresholding and transparency by selecting a color swatch, then clicking or dragging on the Preview. If no swatch is selected, no action is taken. Use care when setting thresholded regions to a color - it could produce some odd-looking images!
Thresholding colors can be chosen via the preview by clicking on one of the four swatches in the Thresholding area, then clicking or dragging on the preview.
If you are viewing the reduced image, transparent colors may be selected by clicking on the Transparent Color Swatch, then clicking or dragging on the Preview. A new transparent color may be selected by clicking on that color in the preview. A click on a color while holding down the Shift key adds that color to the Transparent Range but does not change the current transparent index, and a click on a color while holding down the Apple/Option key subtracts that color from the Transparent Range but does not change the current transparent color index. On export, all colors within the Transparent Range are converted to the index of the transparent color and set to transparent. The size of the color table will be reduced by the number of transparent colors minus 1.
You can use an alpha channel to set transparency by creating an alpha channel in the image before invoking the ColorGIF filter.
The preview button is enabled when any of the color reduction parameters have been modified but are not reflected in the preview. Clicking on the preview button will perform the color reduction according to the current parameters and update the preview. If the preview button is disabled, the current parameter settings are reflected in the preview.
The Width and Height displays the pixel dimensions of the current image. Below this, the GIF Size displays the size in bytes of the image shown in the preview compressed as a GIF file, and the ratio of the GIF file size to the size of the uncompressed RGB image. When viewing the original RGB image, the size is (pixel height) * (pixel width) * (3 bytes). When viewing the reduced image, the size indicates the number of bytes that would be downloaded from a single image GIF file created with the selection.
After a color reduction, Colors indicates the number of colors actually present in the image. If you reducing to a fixed palette or dithering an adaptive palette, this may be less than the total number of colors in the palette. The number of colors used varies depending on the Dither Intensity. Unused colors can be optionally removed from the palette by checking the Optimize check box.
