Scanned images often have black margins or blank spaces around their borders. LEADTOOLS AutoTrim functions can be used to remove unwanted blank edges from images. LEADTOOLS BorderRemove functions remove any or all image borders (black borders surrounding scanned document), with the ability to specify tolerance level for amount of noise, maximum border size, and variability of border size.
Deskew and Rotate
Scanned images are often rotated slightly out-of-plane, leading to automated read (OCR, ICR, OMR, Barcode) errors. There are several ways to correct this using LEADTOOLS:
1. LEADTOOLS Deskew functions automatically straighten scanned images by rotating the specified bitmap. LEAD’s proprietary DeskewCheck function is specifically designed to automatically detect and correct alignment errors in scanned bank checks. Deskew options include background color, interpolation type, and rotation speed.
2. Rotate functions adjust the image data. This is the most portable solution, but it is also the slowest. Therefore, this may not be the best solution for very large images.
3. Using Perspective (API)/ViewPerspective (CLIB) functions, no image data will be altered. LEADTOOLS simply changes the View Perspective of the image so that the origin of the image is altered. Because this method only adjusts a flag (the image data is not touched), it is a very fast. However, some application may not recognize the View Perspective, and the image therefore may not be painted as rotated.
4. If the image is saved in the TIFF format, you can use SetTag functions to adjust the Orientation tag within the TIFF. As for Perspective functions, image data is not touched, but some applications may not recognize the Orientation tag
Scanned images are often too light or too dark. LEADTOOLS MaxFilter and MinFilter functions can be used to lighten or darken images.
LEADTOOLS HolePunchRemove functions remove hole-punch artifacts, specifying min and max hole size and count.
LEADTOOLS LineRemove functions remove horizontal and vertical lines from scanned images, with the ability to specify minimum line length, maximum line width, maximum gap for dashed or otherwise broken lines, tolerance values for line width variance, and other parameters to ensure that valid image obects are preserved.
LEADTOOLS Despeckle and DotRemove functions find and remove dots and specks of various sizes.
LEADTOOLS InvertedText functions detect areas on scanned image of white text (or line objects) on a black background and invert them to black text on a white background. You can specify minimum region size and minimum/maximum percent-of-black to be detected.
LEADTOOLS Smooth functions smooth the nicks and bumps on scanned text characters (or any black-on-white objects), specifying the minimum bump size.