Navigation:  I Want To... > Imaging > Manipulate pixel data

Use Case

Relevant Architecture

Relevant Types

Sample Code

using ClearCanvas.Common;

using ClearCanvas.Desktop.Actions;

using ClearCanvas.Desktop;

using ClearCanvas.ImageViewer;

using ClearCanvas.ImageViewer.BaseTools;

using ClearCanvas.ImageViewer.Graphics;

 

// ... (other using namespace statements here)

 

namespace MyPlugin.Imaging

{

   [ButtonAction("apply", "global-toolbars/ToolbarStandard/ManipulatePixelDataTool", "Apply")]

   [ButtonAction("apply", "global-toolbars/ToolbarStandard/ResetManipulatePixelDataTool", "Unapply")]

   [IconSet("apply", IconScheme.Colour, "Icons.MyToolSmall.png", "Icons.MyToolMedium.png", "Icons.MyToolLarge.png")]

   // ... (other action attributes here)

   [ExtensionOf(typeof (ImageViewerToolExtensionPoint))]

   public class ManipulatePixelDataTool : ImageViewerTool

   {

      public void Apply()

      {

         // Check for nulls before we using anything

         if (this.SelectedImageGraphicProvider == null)

            return;

 

         ImageGraphic image = this.SelectedImageGraphicProvider.ImageGraphic;

 

         if (image == null)

            return;

 

         // Make sure the image is grayscale

         if (!(image is GrayscaleImageGraphic))

            return;

 

         // Change the grayscale value of the pixel at (4,7) (8th row, 5th column)

         image.PixelData.SetPixel(4, 7, 100);

 

         // Redraw the onscreen image

         image.Draw();

 

         // We've modified the original pixel data!

         // To reload it, we will need to call the other method.

      }

 

      public void Unapply()

      {

         // Check for nulls before we using anything

         if (this.SelectedImageSopProvider == null)

            return;

 

         this.SelectedImageSopProvider.Frame.UnloadPixelData();

 

         // Redraw the onscreen image

         this.SelectedPresentationImage.Draw();

      }

   }

}

Remarks

There are two ways to manipulate pixel data:

It's important to remember that by default, ImageGraphic does not own its own pixel data.  Rather, it has a reference to the actual pixel data contained in a Frame (which belongs to an ImageSop).  Because it's possible for more than one ImageGraphic to reference the same pixel data, the pixel data is shared.  This is usually desirable for memory conservation, but may not be desirable when you're performing image processing operations on the data, since any changes to the data will be reflected by all ImageGraphics that reference it.  If you don't want that, you will need to create a copy of the raw data.  At some point, we will add a facility to the Framework that will handle this case automatically without the need for manual copying of pixel data.

If you need to undo the manipulations to the pixel data, you can force the pixel data to unload and, on the next attempt to draw the image, the pixel data will be reloaded from the original Frame.  Since the pixel data is tied to the Frame, the unload method is on the Frame and not on the graphic itself.  Please note that individual frames in a multi-frame image are treated and loaded separately.

Examples in Code Base