Class OcrFilters

A collection of OCR Image filter for processing Images.

Inheritance

System.Object

OcrFilters

Namespace: IronOcr

Assembly: IronOcr.dll

Syntax

public sealed class OcrFilters : Enum

Fields

AdaptiveThreshold

Applies Bradley Adaptive Threshold to the image.

Declaration

public const OcrFilters AdaptiveThreshold

Field Value

Type	Description
OcrFilters

Binarize

This image filter turns every pixel black or white with no middle ground. May Improve OCR performance cases of very low contrast of text to background.

Declaration

public const OcrFilters Binarize

Field Value

Type	Description
OcrFilters

Close

Advanced Morphology. Opposite of Open

Closing is reverse of Opening, Dilation followed by Erosion. It is useful in closing small holes inside the foreground objects.

Declaration

public const OcrFilters Close

Field Value

Type	Description
OcrFilters

Contrast

Increases contrast automatically. This filter often improves OCR speed and accuracy in low contrast scans.

Amount which is used to adjust contrast. A value of 0 will create an image that is completely gray. A value of 1 leaves the input unchanged.

Amount values greater than 0 increase contrast making light areas lighter and dark areas darker.

Amount values less than 0 decrease contrast - decreasing variety of contrast.

Declaration

public const OcrFilters Contrast

Field Value

Type	Description
OcrFilters

DeNoise

Removes digital noise. This filter should only be used where noise is expected. Flattens Alpha channels to white.

Declaration

public const OcrFilters DeNoise

Field Value

Type	Description
OcrFilters

Deskew

Rotates an image so it is the right way up and orthogonal . This is very useful for OCR because Tesseract tolerance for skewed scans can be as low as 5 degrees.

This also helps when producing searchable PDF documents from IronTesseract because the pages will likely all be the right way up.

This version uses only Hough transform to make minor correction. Example: pages that where put in a scanner at a slight angle.

Declaration

public const OcrFilters Deskew

Field Value

Type	Description
OcrFilters

Dilate

Advanced Morphology. Opposite of Erode.

Declaration

public const OcrFilters Dilate

Field Value

Type	Description
OcrFilters

Erode

Advanced Morphology. Opposite of Dilate.

Declaration

public const OcrFilters Erode

Field Value

Type	Description
OcrFilters

Invert

Inverts every color. E.g. White becomes black : black becomes white.

Declaration

public const OcrFilters Invert

Field Value

Type	Description
OcrFilters

None

No filter for processing images.

Declaration

public const OcrFilters None

Field Value

Type	Description
OcrFilters

Open

Advanced Morphology. Opposite of Close

Opening is just another name of erosion followed by dilation. It is useful in removing noise.

Declaration

public const OcrFilters Open

Field Value

Type	Description
OcrFilters

Rotate

Rotates images by a number of degrees clockwise. For anti-clockwise, use negative numbers.

Declaration

public const OcrFilters Rotate

Field Value

Type	Description
OcrFilters

Scale

Scales images up in size by specify width and height.

Declaration

public const OcrFilters Scale

Field Value

Type	Description
OcrFilters

Sharpen

Sharpens blurred OCR Documents. Applies a Gaussian sharpening filter to image.

Declaration

public const OcrFilters Sharpen

Field Value

Type	Description
OcrFilters

value__

Declaration

public int value__

Field Value

Type	Description
System.Int32