Image generator having automatic alignment method and apparatus

Abstract

An image recorder for providing a CRT image and apparatus to store the image on a film disposed on a film plane. The relative position, intensity and focus parameters of the image are measured during an initial startup of the image recorder, wherein the position, intensity and focus parameters of the CRT and the image thereon are automatically aligned to assure enhanced performance. The apparatus according to the present invention provides an alignment mask disposed in the CRT plane and the CRT parameters are measured by observation of the light collected through the alignment mask from the CRT and processing the corresopnding light intensity signals. The light sensing device provides a signal which is processed typically by a microprocessor controlled geometry engine to derive a set of correction data which is based on a prototype array of initialized data values. The correction data provide signals which are combined with uncorrected CRT deflection signals to provide a corrected signal. The parameters corrected by the apparatus and method according to the present invention include x and y position, focus and relative picture intensity over the surface of the screen (vignette). The above-listed parameters are used alone and in combination to provide image centering, image scaling and pincushion correction, correction for non-orthogonality between the x and y deflection coils, image rotation and correction for non-linear second and third order effects. The set of data can also be deliberately distorted to provide image precompensation such as keystone (trapezoid) and spherical corrections as well as vignette compensation such that, when the final image is projected or displayed, a true (nondistorted) image results.

What is claimed is: 
     
       1. An image recorder providing a photographic copy of a CRT image at an image plane onto a photographic film disposed on a film plane in spatial relationship apart from said image plane, comprising: lens means for transforming said image from said image plane to said photographic film;   an alignment mask having a target image thereon overlaying said image at said image plane;   means to selectively illuminate the CRT according to at least one of a deflection signal and an intensity signal;   photodetector means responsive to said target image selectively illuminated by said CRT and producing a target signal therefrom; and   means for adjusting at least one of said deflection signals and said intensity signal according to said target signal in response to said target signal, wherein correction for at least one of image position, rotation, orthogonality, pincushion and size are provided.   
     
     
       2. The image recorder of claim 1, wherein said alignment mask comprises a clear plate .Iadd.having .Iaddend.at least one opaque target thereon. 
     
     
       3. The image recorder of claim .[.2.]. .Iadd.1.Iaddend., further including focus adjustment means responsive to said target signal to provide a focused image on said photographic film. 
     
     
       4. The image recorder of claim 3, wherein said focus adjustment means comprises means for adjusting the focus of said CRT image. 
     
     
       5. The image recorder of claim .[.4.]. .Iadd.1.Iaddend., wherein said CRT image comprises a spot, and said target signal corresponds to the intensity of the CRT image and said means for adjusting the focus of said CRT provides a minimum target signal. 
     
     
       6. The image recorder of claim .[.5.]. .Iadd.1.Iaddend., wherein said alignment mask includes a plurality of said opaque targets distributed over said image plane, said means for adjusting provides said corrections at said targets, and further includes interpolation means for providing said corrections adjacent to said targets.     
     
     
       7. The image recorder of claim 6, wherein said means for adjusting includes: means for detecting an edge of said opaque target; and   means for determining the position of said CRT image according to the detected edge of said target.   
     
     
       8. The image recorder of claim .[.7.]. .Iadd.1.Iaddend., wherein said means for selectively including means to provide a movable illuminated focused spot, and wherein   said means for adjusting further includes means for determining the intensity profile of said spot; and   means for adjusting the focus of said spot according to said intensity profile.     
     
     
       9. The image recorder of claim .[.8.]. .Iadd.1.Iaddend., wherein said means for adjusting includes a prototype mesh for providing preliminary correction. 
     
     
       10. The image recorder of claim 9, wherein said means for adjusting further includes a mesh correction processor responsive to said prototype mesh and said sampled target signal, and providing a corrected mesh signal. 
     
     
       11. The image recorder of claim .[.10.]. .Iadd.1.Iaddend., wherein said means for adjusting includes at least one of: means for sampling the target signal;   multiplication means for providing scaling correction to at least one image characteristic.[.s.]. including image position, rotation, orthogonality, pincushion, size and vignette according to the sampled target signal; and   addition means for providing an offset correction to at least one image characteristic including image position, rotation, orthogonality, pincushion, size and vignette according to the sampled target signal.   
     
     
       12. The image recorder of claim .[.11.]. .Iadd.1.Iaddend., wherein said means for adjusting further includes a random access memory for storing said corrected mesh signal. 
     
     
       13. The image recorder of claim 12, wherein said means for adjusting further includes a geometry engine providing control signals to the CRT including at least one of deflection, focus and vignette signals. 
     
     
       14. An image recorder providing a photographic copy of a CRT image at an image plane on a photographic film disposed on a film plane in spatial relationship apart from said image plane comprising: means for transforming said image from said image plane to said photographic film;   an alignment mask disposed at said film plane having a target image thereon;   means to selectively illuminate the CRT according to at least one of a deflection signal and an intensity signal;   photodetector .[.positive.]. means to receive said target image selectively illuminated by said CRT and producing a target signal therefrom; and   means for adjusting at least one of said deflection signals and said intensity signal according to said target signal in response to said target signal, wherein correction for at least one of image position, rotation, orthogonality, pincushion and size are provided.   
     
     
       15. The image recorder of claim 14 wherein said photographic film is contained within a first removable module, and said alignment mask is contained within a second removable module, wherein   said first and second removable modules are selectively interchangeable.   
     
     
       16. The image recorder of claim .[.15.]. .Iadd.14 .Iaddend.wherein said photographic film is displaced from said film plane and said alignment mask is substituted in the place of the film during adjustment by said means for adjusting.     
     
     
       17. An image recorder providing a photographic copy of a CRT image at a CRT plane on a photographic film, comprising: a film holder including an aperture plate having an aperture therein corresponding to a selected film format and also having means for providing an encoded signal corresponding to said selected format;   encoded signal sense means providing a format signal according to said aperture plate recess;     a CRT display providing said CRT image in response to a video signal and an adjustment signal; and   image adjustment means providing said adjustment signal in response to format size signals for adjusting the CRT image size and position according to said format signals.   
     
     
       18. The image recorder of claim 17, wherein said mechanical encoded signal is provided by recesses in said aperture plate, .Iadd.and .Iaddend. said encoded signal sense means comprises mechanical switches operative according to the presence of said recesses.   
     
     
       19. An image recorder providing a photographic copy of a CRT image at a CRT plane on a photographic film disposed on a film plane in spatial relationship in an optical path apart from said CRT plane, comprising: lens means for transforming said CRT image from said CRT plane to said photographic film;   an alignment mask interposed in said optical path between said film plane and said CRT plane having a target image thereon;   means for selectively illuminating the CRT according to at least one of a deflection signal and an intensity signal;   photodetector means positioned to receive said target image selectively illuminated by said CRT and producing a target signal therefrom; and   means for adjusting at least one of said deflection signals and said intensity signal according to said target signal in response to said target signal, wherein correction for at least one of image position, rotation, orthogonality, pincushion and size are provided.   
     
     
       20. The image recorder of claim 19, wherein said target image comprises one of an opaque, a transparent and a reflective target image. 
     
     
       21. The image recorder of claim 19, wherein said optical path includes a mirror. 
     
     
       22. An image recorder providing a photographic copy of a CRT image at a CRT plane on a photographic film disposed on a film plane in spatial relationship apart from said CRT plane, comprising: lens means for transforming said CRT image from said CRT plane to said photographic film;   an alignment mask overlaying said CRT image at a focal point of said lens means, and having a target image thereon;   means for selectively illuminating the CRT according to at least one of a deflection signal and an intensity signal;   photodetector means positioned to receive said target image selectively illuminated by said CRT and producing a target signal therefrom; and   means for adjusting at least one of said deflection signal and said intensity signal according to said target signal in response to said target signal, wherein correction for at least one of image position, rotation, orthogonality, pincushion and size are provided.   
     
     
       23. An image .[.recorded.]. .Iadd.recorder.Iaddend., comprising: CRT display means selectively providing a two-dimensional CRT image according to one of a plurality of image spatial density of pixels including a higher and a lower pixel density image, wherein each said image .[.pixel.]. density comprises a particular two-dimensioned array of pixels; and   camera means for recording said CRT image on photographic film, wherein said CRT display means includes means for replicating pixels of said lower pixel density image .[.at said two-dimensional array corresponding.]. to said higher .[.image resolution.]. .Iadd.pixel density image .Iaddend.to permit color matching on film.     
     
     
       24. The image recorder of claim 23, wherein said means for replicating provides even multiple replications of the lower resolution image pixels in the two dimensions of the CRT display.   
     
     
       25. A method of alignment of an image recorder having a CRT and a photographic film disposed on a film plane, comprising the steps of: providing an alignment target;   generating a deflection signal according to expected X and Y positions;   selectively illuminating said alignment target with a point light source from said CRT according to said deflection signal, wherein said alignment target partially obscures said selective illumination;   detecting the selectively obscured illumination;   calculating the intensity profile of said point light source; and   adjusting the focus of said point light source according to said intensity profile.   
     
     
       26. The method of claim 25, further including the steps of: calculating the position of said point light source;   comparing the calculated position of said point light source to a specified position and providing an error signal therefrom; and   adjusting said expected position signal according to said error signal.   
     
     
       27. The method of claim 26, further including the step of: adjusting said expected position signal to provide correction for at least one of image position, image rotation, coordinate nonorthogonality, pincushion distortion and size distortion.   
     
     
       28. The method of claim 27, wherein said step of adjusting said expected position signal includes the step of generating a prototype position. 
     
     
       29. A method of aligning a CRT display, comprising the steps of: providing a prototype mesh having preliminary display parameters therein;   correcting said prototype mesh by mask measurements of a predetermined image .Iadd.to provide a final desired mesh.Iaddend.;   storing .[.corrected mesh parameters.]. .Iadd.said final desired mesh.Iaddend.;   generating .[.display parameters.]. .Iadd.correct display parameters frmo said final desired mesh.Iaddend.;   .[.correcting display parameters by said corrected mesh parameters;.]. and   displaying image with .[.corrected.]. .Iadd.said correct .Iaddend.display parameters. .Iadd.   
     
     
       30.  Apparatus for positioning a beam on a scanning-type display comprising: a data mesh containing a set of error corrected deflection values for a plurality of coordinates defining an area of said display, each value corresponding to at least one beam characteristic and derived from a set of alignment factors, said alignment factors representing a parametric model uniquely defining and encompassing the specific characteristics, including errors, of said display;   memory means for storing said data mesh;   means coupled to said memory means for retrieving and converting said data mesh values to deflection signal necessary to correctly position said beam on the display in accordance with said parametric model; and   means for driving said display with said deflection signals. .Iaddend. .Iadd.   
     
     
       31.  The apparatus of claim 30, further comprising: means for storing a prototype mesh derived from a set of nominal factors that represent a nominal model of said display;   means for sampling deflection signals necessary to position said beam at target points on the display;   means responsive to said sampling means for generating said alignment factors; and   means for adjusting said prototype mesh to provide said data mesh based on differences between said alignment factors and said nominal factors. .Iaddend. .Iadd.   
     
     
       32.  Apparatus in accordance with claim 30, wherein said alignment factors include intensity parameters for said display, and said converting means converts corresponding mesh values to an intensity signal for controlling the intensity of said beam. .Iaddend. .Iadd.33. Apparatus in accordance with claim 30, wherein said alignment factors include focus parameters for said display, and said converting means converts corresponding mesh values to a focus signal for controlling the focus of said beam. .Iaddend. .Iadd.34. Apparatus in accordance with claim 30, wherein said data mesh comprises a plurality of mesh control surfaces, each surface containing a two-dimensional array of values for conversion to a difference beam control signal. .Iaddend. .Iadd.35. Apparatus in accordance with claim 34, wherein said beam control signals include X position, Y position, focus, and intensity. .Iaddend. .Iadd.36. Apparatus in accordance with claim 30, further comprising: means for adjusting said data mesh to compensate for distortions in an image input to said apparatus for display. .Iaddend. .Iadd.37. Apparatus in accordance with claim 30 further comprising:   means for interpolating said data mesh to provide an expanded set of mesh   
     
     
        values for conversion into deflection signals. .Iaddend. .Iadd.38. Apparatus in accordance with claim 30 wherein said converting means comprises at least one digital to analog converter. .Iaddend. .Iadd.39. Apparatus in accordance with claim 38 further comprising a low pass filter coupled to an output of said digital to analog converter. .Iaddend. .Iadd.40. An image generator comprising: a data mesh containing a set of error corrected values for a plurality of coordinates defining an image area of said image generator, said values being derived from a set of alignment factors representing a parametric model uniquely defining and encompassing the specific characteristics, including errors, of said image generator;   memory means for storing said data mesh;   means coupled to said memory means for retrieving and converting said data mesh values to image generator control signals;   means for inputting image information to said image generator; and   means responsive to said control signals for outputting said image information in a correct format based on said parametric model. .Iaddend. .Iadd.41. Alignment apparatus for use in combination with the image generator of claim 40, comprising:   a prototype mesh derived from a set of nominal factors that represent a nominal model of said image generator;   means for producing alignment control signals to output an image via said image generator in accordance with predetermined criteria;   means for sampling the alignment control signals when said predetermined criteria are met; and   means responsive to said sampling means for revising said prototype mesh to produce said data mesh based on differences between alignment factors derived from the sampled alignment control signals and said nominal   
     
     
        factors. .Iaddend. .Iadd.42.  Apparatus in accordance with claim 41, wherein said image generator is a scanning-type display. .Iaddend. .Iadd.43. Apparatus in accordance with claim 42 wherein said alignment control signals comprise at least one of a position control signal, intensity control signal, and focus control signal. .Iaddend. .Iadd.44. Apparatus in accordance with claim 42, wherein said data mesh comprises a plurality of mesh control surfaces, each surface containing a two-dimensional array of values for a different parameter of said display. .Iaddend. .Iadd.45. Apparatus in accordance with claim 44 wherein a mesh control surface contains values relating to the positioning of an image on said display. .Iaddend. .Iadd.46. Apparatus in accordance with claim 44 wherein a mesh control surface contains values relating to the intensity of an image on said display. .Iaddend. .Iadd.47. Apparatus in accordance with claim 44 wherein a mesh control surface contains values relating to the focus of an image on said display. .Iaddend. .Iadd.48. Apparatus in accordance with claim 40, wherein said data mesh contains adjusted values to compensate for distortions in an image input to said image generator. .Iaddend. .Iadd.49. Apparatus in accordance with claim 40 wherein said data mesh comprises a plurality of mesh control surfaces, each surface containing a two-dimensional array of values for a different parameter of 
     
     
        said image generator. .Iaddend. .Iadd.50.  A method for aligning an image display comprising the steps of: deriving a prototype mesh from a set of nominal factors that represent a nominal model of a display;   sampling alignment control signals used to display an alignment image on said display in accordance with predetermined criteria;   adjusting said prototype mesh based on differences between alignment factors derived from said sampled alignment control signals and said nominal factors to provide a final desired mesh containing a set of final control values for a plurality of coordinates defining an area of said display, said final control values accounting for errors in said prototype mesh; and   generating display control signals in accordance with said final desired   
     
     
        mesh instead of said prototype mesh. .Iaddend. .Iadd.51.  A method in accordance with claim 50 comprising the further step of: interpolating said final mesh to provide an expanded set of mesh values for use in computing said display control signals. .Iaddend. .Iadd.52. A method in accordance with claim 50 wherein said display control signals comprise an image position signal. .Iaddend. .Iadd.53. A method in accordance with claim 52 wherein said display control signals comprise an intensity signal. .Iaddend. .Iadd.54. A method in accordance with claim 53 wherein said display control signals comprise a focus signal. .Iaddend.