In digital image processing, image enhancement is employed to give a better look to an image. Color is one of the best ways to visually enhance an image. Pseudo-color refers to coloring an image by mapping gray scale values to a three dimensional color space. In this paper we used a pseudo-color technique in frequency domain to enhance ultrasound images. We used three different types of transforms to do this. These are the Fourier transform, Discrete Cosine transform and Walsh- Hadamard transform. After obtaining these pseudo-color images, we applied a high frequency emphasis filter or histogram stretch as a post process. In this paper we used a subjective study to compare images. First we compared pseudo-color images to their original monochrome images. ? Secondly, we compared all the three different types of transforms. Lastly, we compared the post processing techniques.
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