You use this dialog box to modify an existing linear filter or define a new one. Only linear filters (defined by a convolution mask) may be modified or added in ThumbsPlus.
Category. Select the category in which this filter belongs. Categories help to locate specific filters from the many choices.
Order. ThumbsPlus can apply 3x3, 5x5 or 7x7 filters. This selects the size of the filter. If you reduce the size once you've entered values, some will be lost.
Array. Enter the actual pixel accumulation values here. The central value represents the current pixel being processed. Each pixel is multiplied by the corresponding value in the array and added to a total.
Divisor. The sum of pixel x array values is divided by this value. For most filters, this divisor should be the same as the sum of values in the array; the summation button will place this sum in this field.
Bias. This value is added to the result of (Array x pixels) / Divisor. It is used for some effects, such as embossing and etching. It is especially useful when the sum of values in the array is zero.
L. Click to force the array to be left-right symmetrical. All values on the left of the array will be repeated on the right (and if you change a value on the left, it will automatically change on the right). This button is on by default if you edit a filter that is left-right symmetrical.
T. Click to force the array to be top-bottom symmetrical. All values in the top of the array will be repeated automatically on the bottom (and if you change a value on the top, it will automatically change on the bottom). This button is on by default if you edit a filter that is top-bottom symmetrical.
Save. Click this button to save a modified filter under the same name. This button is disabled if you are defining a new filter.
Save As. Click this button to save a modified filter under a different name or specify the name for a new filter.
Remove. Click to remove the current filter from the filter list (THUMBS.FLT). This button is disabled if you are defining a new filter.