Method and apparatus for rapid scanning of color images
First Claim
1. A method for rapid digitization of a transparency which uses an illumination system, optical image forming means, and solid-state detection means having a rectilinear detection pattern, and which provides high resolution, color separation and sizing of the image to any desired scale, comprising the steps of:
- moving the transparency at selected rate in a first direction thus defining a scale factor in a first dimension;
sampling image data obtained through said solid-state detection means at a selected sample rate along a line in a second dimension while defocusing the image to adjust the spatial bandwidth to said selected sample rate;
acquiring for every line sampled a plurality of line data sets each corresponding to a respective spectral band;
rapidly reducing in each of said line data sets, through a predetermined transformation function, the number of colors in the corresponding spectral band used to faithfully represent the original image; and
compensating data in each of said line data sets, through use of predetermined calibration data, for non-uniformities of said illumination system and said solid-state detection means.
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Abstract
A scanner system digitizes 35 mm transparencies or negatives, and converts the image to a format compatible with popular microcomputer systems. This scanner system can accommodate various formats, and has variable zoom, pan and window size. Color separation is accomplished by an illumination arrangement causing rapid sequential generation of red, green and blue components. A low wattage light source is used, and color balance is achieved by adjusting the respective exposure times of the three primary colors. The system has internal calibration to achieve repeatable color balance. The system implements a wide variety of color coding schemes ranging in resolution form 1 to 24 bits. An adaptive process compresses the data in order to optimize the color selection process. The illumination optics are anamorphotic for high efficiency. Mechanical and electrical interfaces are compatible with a conventional 51/4" floppy disk drive standard.
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Citations
24 Claims
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1. A method for rapid digitization of a transparency which uses an illumination system, optical image forming means, and solid-state detection means having a rectilinear detection pattern, and which provides high resolution, color separation and sizing of the image to any desired scale, comprising the steps of:
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moving the transparency at selected rate in a first direction thus defining a scale factor in a first dimension; sampling image data obtained through said solid-state detection means at a selected sample rate along a line in a second dimension while defocusing the image to adjust the spatial bandwidth to said selected sample rate; acquiring for every line sampled a plurality of line data sets each corresponding to a respective spectral band; rapidly reducing in each of said line data sets, through a predetermined transformation function, the number of colors in the corresponding spectral band used to faithfully represent the original image; and compensating data in each of said line data sets, through use of predetermined calibration data, for non-uniformities of said illumination system and said solid-state detection means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 22)
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12. An apparatus for the rapid digitization of a transparency, comprising:
- a light source, an optical image forming element, a solid-state detector having a rectilinear detection pattern, digitization means for providing high resolution and full color rendition and for facilitating sizing of the image to any desired scale,
a variable-feed drive mechanism which establishes a scale factor in a first dimension; an element which provides adjustable defocusing; a rate multiplier which generates a variable scale factor in a second dimension; a color separation element which extracts different spectral bands from the light source; a programmable sequencer which with said color separation element to control respective exposure times assigned to respective said spectral bands; and an arithmetic unit to convert digitized values of respective said spectral bands into a palette containing a reduced number of colors. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 23, 24)
- a light source, an optical image forming element, a solid-state detector having a rectilinear detection pattern, digitization means for providing high resolution and full color rendition and for facilitating sizing of the image to any desired scale,
Specification