ChangeViewPerspective Method

Summary

Rotates and flips the image data as necessary to achieve the desired view perspective.

Syntax

Objective-C

C++

Java

public void ChangeViewPerspective( 
   RasterViewPerspective viewPerspective 
)

Public Sub ChangeViewPerspective( _ 
   ByVal viewPerspective As RasterViewPerspective _ 
)

- (BOOL)changeViewPerspective:(LTRasterViewPerspective)viewPerspective error:(NSError **)error

public void changeViewPerspective(RasterViewPerspective viewPerspective)

public: 
void ChangeViewPerspective(  
   RasterViewPerspective viewPerspective 
)

Parameters

viewPerspective
Desired view perspective.

Remarks

The ViewPerspective is the arrangement of pixels in the image. This method references image coordinates, which are often different from the display coordinates of an image.

Use this method to change the data and the ViewPerspective to simplify calculations that involve image coordinates. This method does not affect the image display. For more information, refer to Accounting for View Perspective.

The following values for viewPerspective are supported in (Document/Medical only) only:

Example

This example demonstrates the low-level methods for accessing 1-bit compressed image data. It demonstrates the ability to get and put rows, and the ability to process rows in buffer-to-buffer processing. The result of the function is an the first 50 lines are inverted.

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Core; 
using Leadtools.ImageProcessing.Color; 
using Leadtools.Dicom; 
using Leadtools.Drawing; 
using Leadtools.Controls; 
using LeadtoolsExamples.Common; 
using Leadtools.Svg; 
 
public void GetRowCompressedExample() 
{ 
   RasterCodecs codecs = new RasterCodecs(); 
   // Load the bitmap, at 1 bit per pixel, compressed 
   codecs.Options.Load.Compressed = true; 
   RasterImage image = codecs.Load(Path.Combine(ImagesPath.Path, "OCR1.TIF"), 1, Leadtools.Codecs.CodecsLoadByteOrder.Bgr, 1, 1); 
 
   // This example does not work with rotated view perspectives. 
   if ((image.ViewPerspective != RasterViewPerspective.TopLeft) || (image.ViewPerspective != RasterViewPerspective.BottomLeft)) 
      image.ChangeViewPerspective(RasterViewPerspective.TopLeft); 
 
   // Adjust the YOffset if the view perspective is bottom left. 
   int nRow = 500; // first row to get. 
   int nYSize = 500; // number of rows to get. 
 
   if (image.ViewPerspective == RasterViewPerspective.BottomLeft) 
      nRow = image.Height - nRow - nYSize; 
 
   // Allocate the buffers. 
   byte[] pBuffer = new byte[Convert.ToInt32((((image.Width + 31) & ~(31)) / 8)) * nYSize]; // Buffer to hold the expanded row. 
   ushort[] pRunBuffer = new ushort[((image.Width + 3) * 2) * nYSize]; // Buffer to hold the compressed row. 
 
   if (image.IsGlobalMemory) 
      image.Access(); 
   // Get the top nRow lines. 
   image.GetRowCompressed(null, pRunBuffer, 0, nRow, nYSize); 
   // Expand the compressed data. 
   RasterRleCompressor.ExpandRows(pRunBuffer, pBuffer, 0, image.Width, nYSize); 
   // Invert the data. 
 
   for (int n = 0; n < (image.BytesPerLine * nYSize); n++) 
      pBuffer[n] ^= 0xff; 
 
 
   // Compress the inverted data. 
   RasterRleCompressor.CompressRows(pRunBuffer, pBuffer, 0, image.Width, nYSize); 
 
   // Put the inverted, compressed data back into the image. 
   image.SetRowCompressed(null, pRunBuffer, 0, nRow, nYSize); 
 
   if (image.IsGlobalMemory) 
      image.Release(); 
 
   codecs.Save(image, Path.Combine(ImagesPath.Path, "IMAGE1_getrowcompresed.BMP"), RasterImageFormat.Bmp, 0); 
 
   image.Dispose(); 
   codecs.Dispose(); 
}

Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.ImageProcessing 
Imports Leadtools.ImageProcessing.Core 
Imports Leadtools.ImageProcessing.Color 
Imports Leadtools.Controls 
Imports Leadtools.Dicom 
Imports Leadtools.Drawing 
Imports Leadtools.Svg 
 
Public Sub GetRowCompressedExample() 
   Dim codecs As RasterCodecs = New RasterCodecs() 
   ' Load the bitmap, at 1 bit per pixel, compressed 
   codecs.Options.Load.Compressed = True 
   Dim image As RasterImage = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "OCR1.TIF"), 1, CodecsLoadByteOrder.Bgr, 1, 1) 
 
   ' This example does not work with rotated view perspectives. 
   If (image.ViewPerspective <> RasterViewPerspective.TopLeft) OrElse (image.ViewPerspective <> RasterViewPerspective.BottomLeft) Then 
      image.ChangeViewPerspective(RasterViewPerspective.TopLeft) 
   End If 
 
   ' Adjust the YOffset if the view perspective is bottom left. 
   Dim nRow As Integer = 500 ' first row to get. 
   Dim nYSize As Integer = 500 ' number of rows to get. 
 
   If image.ViewPerspective = RasterViewPerspective.BottomLeft Then 
      nRow = image.Height - nRow - nYSize 
   End If 
 
   ' Allocate the buffers. 
   Dim pBuffer As Byte() = New Byte(Convert.ToInt32((((image.Width + 31) And Not (31)) / 8)) * nYSize - 1) {} ' Buffer to hold the expanded row. 
   Dim pRunBuffer As System.UInt16() = New System.UInt16(((image.Width + 3) * 2) * nYSize - 1) {} ' Buffer to hold the compressed row. 
 
   image.Access() 
   ' Get the top nRow lines. 
   image.GetRowCompressed(Nothing, pRunBuffer, 0, nRow, nYSize) 
   ' Expand the compressed data. 
   RasterRleCompressor.ExpandRows(pRunBuffer, pBuffer, 0, image.Width, nYSize) 
   ' Invert the data. 
 
   Dim n As Integer = 0 
   Do While n < (image.BytesPerLine * nYSize) 
      pBuffer(n) = pBuffer(n) Xor Convert.ToByte(&HFF) 
      n += 1 
   Loop 
 
 
   ' Compress the inverted data. 
   RasterRleCompressor.CompressRows(pRunBuffer, pBuffer, 0, image.Width, nYSize) 
 
   ' Put the inverted, compressed data back into the image. 
   image.SetRowCompressed(Nothing, pRunBuffer, 0, nRow, nYSize) 
 
   image.Release() 
   codecs.Save(image, Path.Combine(LEAD_VARS.ImagesDir, "IMAGE1_getrowcompresed.BMP"), RasterImageFormat.Bmp, 0) 
 
   image.Dispose() 
   codecs.Dispose() 
End Sub 
 
Public NotInheritable Class LEAD_VARS 
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images" 
End Class

Requirements

Target Platforms

Reference

RasterImage Class

RasterImage Members

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Help Version 20.0.2020.4.2

Leadtools Assembly

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Leadtools Namespace

Leadtools.ImageProcessing Namespace

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