SignDoc SDK (.NET without exceptions)  5.0.0
Cleaning signature images

Cleaning is optimized for signature images, cleaning other images such as photographs won't work. Crop the image to the signature region whenever possible, any elements that are not relevant to a signature might have negative effects on the cleaning process and signature matching.

The following cleaning functions are available:

For these functions, the width of the image must not exceed 1280 pixels, the height of the image must not exceed 960 pixels.

The following functions can be useful for cleaning signature images:

These functions do not restrict the size of the image.

All these functions can be called either directly or by a single call to de.softpro.doc.SignDocImage.clean(). That function takes a de.softpro.doc.SignDocCleanParameters object which specfifies the functions to be called and their parameters.

The signature cleaning engine works on bi-level images only; if you call a cleaning function for an image that is not a bi-level image, a temporary bi-level image will be created and the cleaning function will be applied to that bi-level image. Then, the original image will be masked with the cleaned bi-level image, image, making all parts white that are not considered part of the signature (if the image uses a palette, the brightest color in the palette will be used). The effect of this is that the color of the signature will be maintained.

If the image is a paletted image without valid palette, you should call de.softpro.doc.SignDocImage.invert() first (passing true for aAuto) to ensure that the signature is darker than the background.

Some cleaning functions may reduce the size of the image. If the height or width would become zero, the image will be replaced by a single white pixel (if the image uses a palette, the brightest color in the palette will be used).