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图像变换

执行傅里叶、离散余弦、Radon 和扇形波束变换

图像变换将图像从一个域转换到另一个域。图像通常在空间域中获取和显示,其中相邻像素表示场景的相邻部分。不过,也可以在其他域中获取图像,例如其中相邻像素表示相邻频率分量的频域,或其中相邻像素表示相邻投影角度和径向距离的 Hough 域。在非空间域中查看和处理图像可以识别在空间域中不容易检测到的特征。

函数

houghHough 变换
houghlines基于 Hough 变换提取线段
houghpeaks识别 Hough 变换中的峰值
dct2二维离散余弦变换
dctmtxDiscrete cosine transform matrix
fan2paraConvert fan-beam projections to parallel-beam
fanbeamFan-beam transform
idct2二维逆离散余弦变换
ifanbeamInverse fan-beam transform
iradonInverse Radon transform
para2fanConvert parallel-beam projections to fan-beam
radonRadon 变换
fft2二维快速傅里叶变换
fftshift将零频分量移到频谱中心
ifft2二维快速傅里叶逆变换
ifftshift逆零频平移

主题

  • 傅里叶变换

    了解傅里叶变换及其在图像处理中的一些应用,尤其是在图像滤波中。

  • 离散余弦变换

    了解图像的离散余弦变换 (DCT) 及其应用,特别是在图像压缩中的应用。

  • Hough 变换

    Hough 变换检测图像中的线条,包括从垂直和水平方向以任意角度倾斜的线条。Hough 变换往往很快,但可能会出现伪影。

  • Radon Transform

    The Radon transform detects lines in an image, including lines tilted at arbitrary angles from vertical and horizontal. The Radon transform tends to be more accurate at the cost of longer computation time.

  • The Inverse Radon Transformation

    The inverse Radon transform reconstructs an image from a set of parallel-beam projection data across many projection angles.

  • Fan-Beam Projection

    Use fan-beam projection and reconstruction when projections of an image are acquired along paths radiating from a point source. Medical tomography is a common application of fan-beam projection.