Method for focusing a film scanner and film scanner for carrying out the method
View Patent ↗A method for focussing a film scanner provides for selecting a plurality of partial regions of the picture to be scanned for the purpose of focus monitoring. During the focussing of one of the selected partial regions, the focussing of the other partial regions is simultaneously monitored. The monitoring is effected for example by simultaneous representation of the partial regions on a monitor screen, and/or by evaluation of the frequency and amplitude conditions of the partial regions. An optimum focal point is set if all the selected partial regions are simultaneously set sharply.
1. A method for focusing a film scanner, the method comprising: converting image information of a film image to be scanned into electrical signals in a scanning unit of the film scanner, the electrical signals representing the scanned film image, and the scanning unit being assigned an optical unit of variable focus; displaying the electrical signals of the scanned film image on a monitoring screen; selecting a plurality of subareas of the film image to be scanned for the purpose of focus control, each of the selected subareas are separated from each other selected subarea; dividing the monitoring screen into a plurality of separate display areas corresponding to each of the selected subareas that are separated from each other selected subarea; simultaneously displaying the image information for each of the selected subareas that are separated from each other selected subarea of the film image to be scanned on an enlarged scale in the separate display areas of the monitoring screen; focusing at least a first one of the selected subareas by changing the focusing of the optical unit while simultaneously monitoring a variation in the focusing of the other selected subareas, wherein focusing is determined based on a structure of a film grain; and evaluating the frequency and amplitude information of the electrical signal for each of the selected subareas while changing the focusing of the optical unit, wherein the changing of the focusing is terminated when the sum of the amplitude information of the electric signals of the selected subareas reaches a maximum for high frequencies.
2. The method of claim 1 , wherein during the focusing of the at least one selected subarea, the image information of the other selected subareas is monitored, and the optical unit is configured for focusing such that each of the selected subareas are focusing in a similar manner.
3. The method of claim 1 , further comprising: superimposing the frequency and amplitude information for the selected subareas into the display areas as graphs representing an amplitude-over-frequency distribution.
4. The method of claim 1 , further comprising:
displaying the complete image to be scanned as background behind the subareas displayed on a large scale.
5. The method of claim 1 , wherein the focusing is performed on a structure of film grain of the film image to be scanned.
6. A film scanner set up to carry out the method according to claim 1 .