Basic investigation on medical ultrasonic echo image compression by JPEG2000-availability of wavelet transform and ROI method

Lossy pulse-echo ultrasonic image compression by a JPEG baseline system is permitted by DICOM. In addition to the use of JPEG, use of JPEG2000 will be approved in the near future. The main features of JPEG2000 are use of wavelet transform and ROI (Region of Interest) method. It is expected that wavelet transform is more effective than the Fourier transform for ultrasonic echo signal/image processing. Furthermore, ROI method seems to be appropriate compression method of medical images. The purpose of this paper is to investigate the effectiveness of wavelet transform compared with DCT (JPEG) and ROI method for medical ultrasonic echo image compression. The image quality is evaluated by PSNR and the subjective assessment by medical doctors and ultrasonographers. Results reveal that wavelet transform achieves a lower bit rate compared with DCT under the same image quality. In regard to ROI method, it is important that how place of ROI is determined and how much image quality in the other region is reduced.