PdfDCTDecodeFilter Class

Namespace:
GemBox.Pdf.Filters
Assembly:
GemBox.Pdf.dll

The DCTDecode filter decodes grayscale or color image data that has been encoded in the JPEG baseline format.

public sealed class PdfDCTDecodeFilter : PdfFilter
Public NotInheritable Class PdfDCTDecodeFilter
    Inherits PdfFilter
Inheritance:
System.Object
PdfDCTDecodeFilter

Properties

ColorTransform

A value specifying the transformation that shall be performed on the sample values:

  • 0No transformation.
  • 1If the image has three color components, RGB values shall be transformed to YUV before encoding and from YUV to RGB after decoding. If the image has four components, CMYK values shall be transformed to YUVK before encoding and from YUVK to CMYK after decoding. This option shall be ignored if the image has one or two color components.

Default value: true if the image has three components; otherwise, false.

public bool? ColorTransform { get; set; }
Public Property ColorTransform As Boolean?
Property Value
System.Nullable<System.Boolean>

The value specifying the transformation that shall be performed on the sample values.

Remarks

If the encoding algorithm has inserted the Adobe-defined marker code in the encoded data indicating the ColorTransform value, then the colors shall be transformed, or not, after the DCT decoding has been performed according to the value provided in the encoded data and the value of this property shall be ignored. If the Adobe-defined marker code in the encoded data indicating the ColorTransform value is not present then the value specified in this property will be used. If the Adobe-defined marker code in the encoded data indicating the ColorTransform value is not present and value of this property is null then the default value of ColorTransform shall be true if the image has three components and false otherwise.

Parameters that control the decoding process as well as other metadata is embedded within the encoded data stream using a notation referred to as "markers". When it defined the use of JPEG images within PostScript data streams, Adobe System Incorporated defined a particular set of rules pertaining to which markers are to be recognized, which are to be ignored and which are considered errors. A specific Adobe-defined marker was also introduced. The exact rules for producing and consuming DCT encoded data within PostScript are provide in Adobe Technical Note #5116 (reference). PDF DCT Encoding shall exactly follow those rules established by Adobe for PostScript.

Exceptions
InvalidPdfDictionaryEntryException

Value is not according to PDF Specification ISO 32000-1:2008.

See Also

FilterType

Gets the DCTDecode value.

public override PdfFilterType FilterType { get; }
Public Overrides ReadOnly Property FilterType As PdfFilterType
Property Value
PdfFilterType

The DCTDecode value.

Overrides

Inherited Methods

Equals(System.Object)

Determines whether the specified System.Object is equal to this PdfFilter instance.

(Inherited from PdfFilter)

GetHashCode()

Returns a hash code for this PdfFilter instance.

(Inherited from PdfFilter)

ToString()

Returns a System.String that represents this PdfFilter instance.

(Inherited from PdfFilter)

See Also