GetTransformationParameters Method

Summary

Computes the rotation angle, XY scaling, and XY translation of the transformed image with comparison to the reference image. These are the transformations that would have to be performed to the reference image to have it match the current image. This method is available in the Document/Medical Toolkits.

Syntax

Objective-C

C++/CLI

Java

Python

public static TransformationParameters GetTransformationParameters( 
   RasterImage image, 
   LeadPoint[] referencePoints, 
   LeadPoint[] transformedPoints 
)

+ (nullable LTTransformationParameters *)getTransformationParameters:(LTRasterImage *)image 
                                                     referencePoints:(nullable NSArray<NSValue *> *)referencePoints /*LeadPoint*/ 
                                                   transformedPoints:(nullable NSArray<NSValue *> *)transformedPoints /*LeadPoint*/ 
                                                               error:(NSError **)error

public static TransformationParameters getTransformationParameters( 
   RasterImage image, 
   LeadPoint[] referencePoints, 
   LeadPoint[] transformedPoints 
);

public: 
static TransformationParameters GetTransformationParameters(  
   RasterImage^ image, 
   array<LeadPoint>^ referencePoints, 
   array<LeadPoint>^ transformedPoints 
)

def GetTransformationParameters(self,image,] referencePoints,] transformedPoints):

Parameters

image
RasterImage object that references the transformed image.

referencePoints
Pointer to an array of reference points. These points represent the center of mass points for the registration marks in the reference image. You have to provide this information.

transformedPoints
Pointer to an array of transformed points. These points are the center of mass points in the image. You have to provide this information.

Return Value

TransformationParameters

Remarks

This method detects transformation parameters of the transformed image by comparing it with the reference image. The number of reference and detected points must be three.
Use GetRegistrationMarksCenterMass to fill the referencePoints array with the points representing the center of masses for each of the reference marks from the reference image.
Fill the transformedPoints array by performing the following steps:
- Use SearchRegistrationMarksCommand to find the new positions for the reference marks.
- Using GetRegistrationMarksCenterMass to fill the transformedPoints array with points representing the center of masses for each of the transformed reference marks.
The properties of TransformationParameters which are: XTranslation, YTranslation, Angle, XScale and YScale are internally divided by 100. For example, an Angle of 500 would mean to rotate the image 5 degrees clockwise.
The results of this method must be sent without any modification to the ApplyTransformationParameters method in order to correct the image.
If you want to correct the image yourself, you have to perform the inverse operations in this order:
- Shift the image by (-TransformationParameters.XTranslation / 100, -TransformationParameters.YTranslation / 100) using CombineCommand
- Rotate without resizing by - (TransformationParameters.Angle)
- Resize using scaling factors of (100 / TransformationParameters.XScale, 100 / TransformationParameters.YScale) using SizeCommand or ResizeCommand.
If you simply want to automatically straighten the image, use the DeskewCommand.
This method supports 12 and 16-bit grayscale and 48 and 64-bit color images. Support for 12 and 16-bit grayscale and 48 and 64-bit color images is available only in the Document/Medical toolkits.
This command does not support signed images.

For more information, refer to Detecting Registration Marks.

Example

This example computes the translation parameters. The example makes the assumption that you have saved the position of the registration marks of the reference image in a file. You should modify this example and replace the manual assignment of the rmData with your own code to load the reference registration mark data before testing this example.

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Core; 
 
 
public void GetTransformationParametersExample() 
{ 
   // Load an image 
   RasterCodecs codecs = new RasterCodecs(); 
   codecs.ThrowExceptionsOnInvalidImages = true; 
 
   RasterImage image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "RGSRef.cmp")); 
 
   // Prepare the command 
   SearchRegistrationMarksCommandData[] rmData = new SearchRegistrationMarksCommandData[3]; 
 
   //Mark1 
   rmData[0] = new SearchRegistrationMarksCommandData(); 
   rmData[0].Rectangle = new LeadRect(680, 20, 941 - 680, 218 - 20); 
   rmData[0].MarkDetectedPoints = new LeadPoint[1]; 
   rmData[0].Width = 31; 
   rmData[0].Height = 29; 
   rmData[0].Type = RegistrationMarkCommandType.TShape; 
   rmData[0].MinimumScale = 90; 
   rmData[0].MaximumScale = 110; 
   rmData[0].SearchMarkCount = 1; 
 
   //Mark2 
   rmData[1] = new SearchRegistrationMarksCommandData(); 
   rmData[1].Rectangle = new LeadRect(665, 790, 899 - 665, 961 - 790); 
   rmData[1].MarkDetectedPoints = new LeadPoint[1]; 
   rmData[1].Width = 31; 
   rmData[1].Height = 29; 
   rmData[1].Type = RegistrationMarkCommandType.TShape; 
   rmData[1].MinimumScale = 90; 
   rmData[1].MaximumScale = 110; 
   rmData[1].SearchMarkCount = 1; 
 
   //Mark3 
   rmData[2] = new SearchRegistrationMarksCommandData(); 
   rmData[2].Rectangle = new LeadRect(7, 1073, 298 - 7, 1246 - 1073); 
   rmData[2].MarkDetectedPoints = new LeadPoint[1]; 
   rmData[2].Width = 31; 
   rmData[2].Height = 29; 
   rmData[2].Type = RegistrationMarkCommandType.TShape; 
   rmData[2].MinimumScale = 90; 
   rmData[2].MaximumScale = 110; 
   rmData[2].SearchMarkCount = 1; 
   SearchRegistrationMarksCommand command1 = new SearchRegistrationMarksCommand(rmData); 
   command1.Run(image); 
   if ((rmData[2].MarkDetectedCount != 1) || (rmData[1].MarkDetectedCount != 1) || (rmData[0].MarkDetectedCount != 1)) 
      return; 
 
   LeadPoint[] original = 
   { 
      new LeadPoint(81400, 11300), 
      new LeadPoint(78600, 87400), 
      new LeadPoint(14300, 115400) 
   }; 
 
   LeadPoint[] detected = 
   { 
      rmData[0].MarkDetectedPoints[0], 
      rmData[1].MarkDetectedPoints[0], 
      rmData[2].MarkDetectedPoints[0] 
   }; 
 
   //Find center of mass for detected registration marks in the transformed image 
   LeadPoint[] transformed = CoreUtilities.GetRegistrationMarksCenterMass(image, detected); 
   //Find transformation parameters 
   TransformationParameters parameters = CoreUtilities.GetTransformationParameters(image, original, transformed); 
   //Apply transformation parameters to correct the image 
   ApplyTransformationParametersCommand applyCommand = new ApplyTransformationParametersCommand(parameters.XTranslation, parameters.YTranslation, parameters.Angle, parameters.XScale, parameters.YScale, 
         ApplyTransformationParametersCommandFlags.Normal); 
   applyCommand.Run(image); 
 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS22\Resources\Images"; 
}