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LEADTOOLS (Leadtools assembly)
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ChangeViewPerspective Method








Leadtools Namespace > RasterImage Class : ChangeViewPerspective Method
Desired view perspective.
Rotates and flips the image data as necessary to achieve the desired view perspective.
Syntax
public void ChangeViewPerspective( 
   RasterViewPerspective viewPerspective
)
'Declaration
 

Public Sub ChangeViewPerspective( _
   ByVal viewPerspective As RasterViewPerspective _
) 
'Usage
 

Dim instance As RasterImage
Dim viewPerspective As RasterViewPerspective
 
instance.ChangeViewPerspective(viewPerspective)
public void ChangeViewPerspective( 
   RasterViewPerspective viewPerspective
)
- (BOOL)changeViewPerspective:(LTRasterViewPerspective)viewPerspective error:(NSError **)error
public void changeViewPerspective(RasterViewPerspective viewPerspective)
 function Leadtools.RasterImage.ChangeViewPerspective( 
   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.

Copy Code   
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.

   If image.IsGlobalMemory Then
      image.Access()
   End If
   ' 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)

   If image.IsGlobalMemory Then
      image.Release()
   End If

   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
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 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();
}
Requirements

Target Platforms

See Also

Reference

RasterImage Class
RasterImage Members

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