Where does PixColormap live in the IronOCR API?

PixColormap is a sealed class in the DynamicTesseract namespace, shipped in IronOcr.dll. It derives from System.Object and implements IDisposable, so dispose it after editing. It represents the color palette of a colormapped Leptonica image.

How do you build a color palette in C# with PixColormap?

Call the static PixColormap.Create with a bit depth to allocate an empty map, or CreateLinear for a grayscale ramp, then call AddColor or AddNewColor with a PixColor for each entry. Read entries by position through the Item indexer and dispose the map when finished.

What is the difference between AddColor, AddNewColor, and AddNearestColor?

AddColor appends a PixColor to the palette. AddNewColor adds one only if it is not already present and returns its index. AddNearestColor does not add a color but returns the index of the closest existing entry to the requested color.

Class PixColormap

Inheritance

System.Object

PixColormap

Implements

System.IDisposable

Namespace: DynamicTesseract

Assembly: IronOcr.dll

Syntax

public sealed class PixColormap : Object

PixColormap manages the palette of a colormapped Leptonica image, the indexed table that maps each pixel value to an actual PixColor. It is the type code works through when an image stores colors by index rather than per pixel, for example a quantized scan whose palette must be inspected or edited before recognition. Most text OCR never touches it, but color cleanup and image-preparation steps do.

A colormap is created through the static factories rather than a constructor: Create allocates an empty map of a given bit depth, while the two CreateLinear overloads build a ready-made grayscale ramp. Because the type holds a native handle and implements IDisposable, dispose it (or use using) once editing is finished. Count reports how many colors the map currently holds, FreeCount how many slots remain, and Depth the bit depth that bounds its capacity.

Colors are added and queried through the palette methods. AddColor appends a PixColor, AddNewColor adds one only if it is not already present and returns its index, and AddNearestColor maps a requested color to the closest existing entry. AddBlackOrWhite and SetBlackOrWhite manage the black and white endpoints, IsUsableColor tests whether a color can be added within the depth limit, and the Item indexer reads an entry by position. Clear empties the map for reuse. Build each entry from a PixColor, the RGBA color this table indexes.

using DynamicTesseract;

using PixColormap map = PixColormap.Create(8);
map.AddColor(new PixColor(0, 0, 0, 255));
map.AddNewColor(new PixColor(255, 255, 255, 255), out int whiteIndex);

The replace color example edits image colors before OCR, the image color correction how-to covers color cleanup, and the select text by color example matches palette colors.

Properties

Count

Declaration

public int Count { get; }

Property Value

Type	Description
System.Int32

Depth

Declaration

public int Depth { get; }

Property Value

Type	Description
System.Int32

FreeCount

Declaration

public int FreeCount { get; }

Property Value

Type	Description
System.Int32

Item[Int32]

Declaration

public PixColor this[int index] { get; set; }

Parameters

Type	Name	Description
System.Int32	index

Property Value

Type	Description
PixColor

Methods

AddBlackOrWhite(Int32, out Int32)

Declaration

public bool AddBlackOrWhite(int color, out int index)

Parameters

Type	Name	Description
System.Int32	color
System.Int32	index

Returns

Type	Description
System.Boolean

AddColor(PixColor)

Declaration

public bool AddColor(PixColor color)

Parameters

Type	Name	Description
PixColor	color

Returns

Type	Description
System.Boolean

AddNearestColor(PixColor, out Int32)

Declaration

public bool AddNearestColor(PixColor color, out int index)

Parameters

Type	Name	Description
PixColor	color
System.Int32	index

Returns

Type	Description
System.Boolean

AddNewColor(PixColor, out Int32)

Declaration

public bool AddNewColor(PixColor color, out int index)

Parameters

Type	Name	Description
PixColor	color
System.Int32	index

Returns

Type	Description
System.Boolean

Clear()

Declaration

public void Clear()

Create(Int32)

Declaration

public static PixColormap Create(int depth)

Parameters

Type	Name	Description
System.Int32	depth

Returns

Type	Description
PixColormap

CreateLinear(Int32, Boolean, Boolean)

Declaration

public static PixColormap CreateLinear(int depth, bool firstIsBlack, bool lastIsWhite)

Parameters

Type	Name	Description
System.Int32	depth
System.Boolean	firstIsBlack
System.Boolean	lastIsWhite

Returns

Type	Description
PixColormap

CreateLinear(Int32, Int32)

Declaration

public static PixColormap CreateLinear(int depth, int levels)

Parameters

Type	Name	Description
System.Int32	depth
System.Int32	levels

Returns

Type	Description
PixColormap

Dispose()

Declaration

public void Dispose()

IsUsableColor(PixColor)

Declaration

public bool IsUsableColor(PixColor color)

Parameters

Type	Name	Description
PixColor	color

Returns

Type	Description
System.Boolean

SetBlackOrWhite(Boolean, Boolean)

Declaration

public bool SetBlackOrWhite(bool setBlack, bool setWhite)

Parameters

Type	Name	Description
System.Boolean	setBlack
System.Boolean	setWhite

Returns

Type	Description
System.Boolean

Implements

System.IDisposable