1 / 11

Modulation Transfer Function

Modulation Transfer Function. Kurt Rose, Nadya Spice, Stefano Prezioso. What are MTF’s ?. MTF’s characterize the sharpness of an imaging system. (Lens, image sensor, film, etc.) Modulation Transfer Functions are measurements made in the frequency domain.

masao
Download Presentation

Modulation Transfer Function

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Modulation Transfer Function Kurt Rose, Nadya Spice, Stefano Prezioso

  2. What are MTF’s? • MTF’s characterize the sharpness of an imaging system. (Lens, image sensor, film, etc.) • Modulation Transfer Functions are measurements made in the frequency domain. • They’re also known as a spatial frequency response.

  3. What do they do? • MTF’s are used to measure how accurately the lens can reproduce detail from an object to an image. Basically, they can tell when the cameras resolution falls off.

  4. What do they look like? The values in image A are black (0) and white (255).  If we plot these points, you will get a graph that looks like image C.  Now if you photograph image A, the lens will blur the bars in a horizontal direction shown in image B.  If you plot the points in image B, you will get a graph that looks like image D.   http://photo.net/learn/optics/mtf/blur2.gif

  5. Why does it blur? • Light travels in generally straight lines. However, if begins to “diffract” when it travels through a small hole such as an aperture. Large Aperture Small Aperture Diffraction Pattern The reason why it diffracts, even though it’s going through a straight line is because the some of the light has to travel farther to get to the sensor.

  6. To find MTF’s You need to photograph a sine test target. Like this super awesome one in the 3rd year lab!

  7. Using software like ImageJ, record the mean pixel value for every black and white band. Similar to the TTF plots we found.

  8. Next measure the max + min of the sin wave and pixel distance in between. M=(Max – Min)/(Max + Min) Find the physical size of the pixels by using this formula. (Pixels x Sensor Size)/(Image Size) This should give you the pixel size in mm or similar units Plot 1/Physical Size [mm]. This will give you the spatial frequency of the cycle.

  9. This is what a MTF should look like.

  10. We are still in the process of figuring out how exactly to plot them. This is our data collected from this sin target.

  11. http://www.normankoren.com/Tutorials/MTF.html http://photo.net/learn/optics/mtf/ http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm Thank you, third year students! (Specifically Meghan).

More Related