page_title: Contrast transfer function
hierarchical_section_title: Contrast transfer function
caption_attribution_description: English: w:Contrast transfer function from a micrograph collected on an FEI Tecnai F20 G2 w:electron microscope. Image obtained by taking the power spectra of an electron micrograph of a biological sample in uranyl acetate stain and apply some rotational blurring using w:GIMP
context_page_description: The contrast transfer function mathematically describes how aberrations in a transmission electron microscope modify the image of a sample. This contrast transfer function sets the resolution of high-resolution transmission electron microscopy, also known as phase contrast TEM.
  By considering the recorded image as a CTF-degraded true object, describing the CTF allows the true object to be reverse-engineered. This is typically denoted CTF-correction, and is vital to obtain high resolution structures in three-dimensional electron microscopy, especially electron cryo-microscopy. Its equivalent in light-based optics is the optical transfer function.
context_section_description: The contrast transfer function (CTF) mathematically describes how aberrations in a transmission electron microscope (TEM) modify the image of a sample. This contrast transfer function (CTF) sets the resolution of high-resolution transmission electron microscopy (HRTEM), also known as phase contrast TEM.
  By considering the recorded image as a CTF-degraded true object, describing the CTF allows the true object to be reverse-engineered. This is typically denoted CTF-correction, and is vital to obtain high resolution structures in three-dimensional electron microscopy, especially electron cryo-microscopy. Its equivalent in light-based optics is the optical transfer function.
caption: Power spectrum (Fourier transform) of a typical electron micrograph.  The effect of the contrast transfer function can be seen in the alternating light and dark rings (Thon rings), which show the relation between contrast and spatial frequency.
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