Abstract: In the current research and design of spectrogram based on Field Programmable Gate Array (FPGA), the direct indication of the spectrogram is not able to reflect the detail variation of spectrum. To solve this problem, a method for the display and enhancement of spectrogram based on FPGA was proposed in this paper. With nonlinear transformation, the high-resolution gray image was compressed to low gray-resolution image, so the detail variation of spectrum would be better reflected. Meanwhile，human vision is less sensitive to the difference between gray-scale pixels than that of colors, so with pseudo-color processing of the gray images, the results are displayed through Video Graphics Array (VGA). The experimental results show that more detail variation of spectrum can be obtained by the method.

Key words: Field Programmable Gate Array (FPGA), spectrogram, Short Time Fourier Transform (STFT), nonlinear transformation, pseudo-color

摘要： 在基于现场可编程门阵列(FPGA)的语谱分析研究与设计中，直接显示的语谱图不能够体现语谱的细节变化情况，针对这一问题，提出了一种适合FPGA实现的语谱图增强显示的方法。该方法通过非线性变换，将高灰度分辨率图像压缩为低灰度分辨率图像，能更好地体现语谱图的细微变化。由于人眼对灰度的分辨能力远低于对色彩的分辨能力，对灰度图像进行了伪彩色处理，并将结果通过视频图形阵列(VGA)方式显示。实验结果表明，通过该方法可以获得更多的语谱图所表达的视觉细节信息。

关键词: 现场可编程门阵列, 语谱图, 短时傅里叶变换, 非线性变换, 伪彩色