| 摘要 |
<p>1501660 Generating an improved image of a printed character INTERNATIONAL BUSINESS MACHINES CORP 31 Oct 1975 [27 Jan 1975] 45273/75 Heading G4R An improved image of a printed character is produced by forming a first amplitude function representing the amplitude of the intensity of each elemental portion of the character, e.g. by scanning, by transforming the amplitude function using a Fourier transformation to produce a second function, by operating on the second function using a filter function, forming a second amplitude function from the filtered function using a Fourier transformation and converting the second amplitude function into an image of the character. Printed characters often contain defects such as comet tails (Fig. 1c) which have a periodic structure due to the structure of the inking ribbon. Such a character is scanned using equidistant rastering and the signal so produced is digitized. The function produced is Fourier transformed into a frequency function in which periodic features in the character due to the comet tails form local concentrations or singularities. The frequency function is multiplied by a filter function which removes these periodic features and is then transformed using a Fourier retransformation into an amplitude function. The transformations can be performed using programmed ditital computers.</p> |
