Manipulating DICOM Formats

Adjusting Brightness, Contrast and Gamma

Color adjustments in digital images is one of the core features that most of the imaging libraries provide. Color adjustments can be categorized in the following.

  1. Brightness refers to the lightness or darkness of color. Increasing the brightness of an image lights out all colors whereas decreasing the brightness darkens all colors.
  2. Contrast refers to making the objects or details within an image more obvious. Increasing the contrast of an image increases the difference between light and dark areas so that the light areas becomes lighter and dark areas becomes darker. Decreasing the contrast will make lighter and darker areas stay approximately the same but the overall image becomes more homogeneous.
  3. Gamma optimizes the contrast and brightness of the indirect lighting that is illuminating an object in the image.

Adjusting Brightness

Aspose.Imaging for .NET API provide AdjustBrightness method for the DicomImage class that can be used to adjust the Brightness by passing an integer value as parameter.

Adjusting Contrast

The AdjustContrast method exposed by the DicomImage class can be used to adjust the Contrast of an image by passing a float value as parameter.

Adjusting Gamma

The AdjustGamma method exposed by the DicomImage class can be used to adjust the Gamma of an image by passing a float value as parameter.

Applying Filters

This article demonstrates the usage of Aspose.Imaging for .NET to apply filter on a DICOM image. Aspose.Imaging APIs have exposed efficient & easy to use methods to achieve this goal. The following code example demonstrates how to apply filter on DICOM image.

Applying Binarization

In order to understand the concept of Binarization, it is important to define a Binary Image; that is a digital image that can have only two possible values for each pixel. Normally, the two colors used for a binary image are black and white though any two colors can be used. Binarization is the process of converting an image to bi-level meaning that each pixel is stored as a single bit (0 or 1) where 0 denotes the absence of color and 1 means presence of color. Aspose.Imaging for .NET API supports three different methods of binarization for DICOM images.

Using Fixed Threshold

Following code snippet demonstrates how Fixed Threshold Binarization can be applied to a DICOM image.

Using Otsu Threshold

Following code snippet demonstrates how Otsu Threshold Binarization can be applied to a DICOM image.

Using Bradley’s Adaptive Threshold

Following code snippet demonstrates how Bradley’s Adaptive Threshold Binarization can be applied to a DICOM image.

Using Grayscaling

Gray-scaling is the process of converting a continuous-tone image to an image with discontinues gray shades.

Cropping Image

Image cropping usually refers to the removal of the outer parts of an image to help improve the framing. Cropping may also be used to take out some portion of an image to increase the focus on a particular area. Aspose.Imaging for .NET API now supports DICOM image cropping.

Cropping by Shifts

The DicomImage class provides the Crop method that accepts 4 integer values. Based on these four values, the Crop method take out that part of the image while discarding the rest of the image. The code snippet below demonstrates how to crop a DICOM image.

Dithering For DICOM Image

Dithering is a technique of creating the illusion of new colors and shades by varying the pattern of dots that actually create an image. It is the most common means of reducing the color range of images down to the 256 (or fewer) colors. Aspose.Imaging provides the dithering support for DicomImage class by introducing Dither method that accepts two parameters. First is of type DitheringMethod to be applied with two possible options FloydSteinbergDithering and ThresholdDithering. The second parameter to Dither method is the BitCount in integer. BitCount defines the sampling size for the dithering result. Default value is 1 that represents black and white, whereas allowed values are 1, 4, 8 generating palettes with 2, 4 and 256 colors respectively.

Resizing DICOM Image

This article demonstrates the usage of Aspose.Imaging for .NET to perform Resize operation on a DICOM image. Aspose.Imaging APIs have exposed efficient & easy to use methods to achieve this goal. Aspose.Imaging for .NET has exposed the Resize method of the DicomImage class that can be used to re-size existing images on the fly. The steps to perform Resize are as simple as below:

  1. Load in image using the constructor of the DicomImage class.
  2. Call the DicomImage.Resize method while specifying new Height & Width.
  3. Save the results.

Simple Resizing

The following code example demonstrates how to Resize an image.

Other Resizing Options

Aspose.Imaging API has exposed ResizeHeightProportionally and ResizeWidthProportionally methods of the DicomImage class that can be used to re-size the DICOM images. These methods take in an integer as first argument and ResizeType enumeration to achieve desired results. Below provided code snippet demonstrates the usage of these methods.

Rotate and Flip DICOM Image

Aspose.Imaging for .NET has provided Rotate and RotateFlip methods of DicomImage class to rotate/flip a DICOM image. The DicomImage.Rotate method can be used to rotate the image. The Rotate method take an integer parameter as degrees to rotate. DicomImage.RotateFlip method accepts a parameter of RotateFlipType that specifies the type of rotation and flip to apply to the image. The steps to perform Rotate & Flip are as simple as below:

  1. Load in image using the DicomImage class constructor.
  2. Call the DicomImage.RotateFlip or DicomImage.Rotate method while specifying the appropriate parameter.
  3. Save the results.

Export to DICOM

Aspose.Imaging supports export from various raster file formats including multi-paged to DICOM. Below there are some examples related to this.

Support of Jpeg, Jpeg2000 and RLE compression methods in Dicom

Dicom format can be compressed using Jpeg, Jpeg2000 and RLE compressions.

Memory strategy optimization

The memory optimization strategy is now supported for Dicom images.

Here are some examples of its use: