Richard W D, Arthur R M
Department of Electrical Engineering, Washington University, St. Louis, MO 63130.
Ultrason Imaging. 1994 Apr;16(2):109-23. doi: 10.1177/016173469401600204.
Scan conversion is required in order to display conventional B-mode ultrasonic signals, which are acquired along radii at varying angles, on standard Cartesian-coordinate video monitors. For real-time implementations, either nearest-neighbor or bilinear interpolation is usually used in scan conversion. If the sampling rate along each radius is high enough, however, the gray-scale value of a given pixel can be interpolated accurately using the nearest samples on two adjacent vectors. The required interpolation then reduces to linear interpolation. Oversampling by a factor of 2 along with linear interpolation was superior to bilinear interpolation of vectors sampled to match pixel-to-pixel spacing in 6 representative B-mode images. A novel 8-bit linear interpolation algorithm was implemented as a CMOS VLSI circuit using a readily available, high-level synthesis tool. The circuit performed 30 million interpolations per second. Arithmetic results produced by the 8-bit interpolator on 7-bit samples were virtually identical to IEEE-format, single-precision, floating-point results.
为了在标准笛卡尔坐标视频监视器上显示传统的B模式超声信号（这些信号是沿不同角度的半径采集的），需要进行扫描转换。对于实时实现，扫描转换通常使用最近邻插值或双线性插值。然而，如果沿每个半径的采样率足够高，则可以使用两个相邻向量上的最近样本准确地对给定像素的灰度值进行插值。此时所需的插值就简化为线性插值。在6幅代表性的B模式图像中，沿向量以2倍因子过采样并结合线性插值优于对采样进行双线性插值以匹配像素到像素间距的情况。一种新颖的8位线性插值算法使用现成的高级综合工具实现为CMOS超大规模集成电路。该电路每秒执行3000万次插值。8位插值器对7位样本产生的算术结果与IEEE格式的单精度浮点结果几乎相同。
