Abstract:
A tunable Fabry-Perot filter (8, 118, 218, 318, 418) includes substrates (10, 12) with parallel generally planar facing principal surfaces (14, 16) including spaced apart facing reflective surface regions (20, 22) that are at least partially reflective over a wavelength range and define an optical gap (Gopt) therebetween. At least one substrate of the pair of substrates is light transmissive over the selected wavelength range to enable optical coupling with the optical gap. Electrodes (24, 26) are disposed on the facing principal surfaces of the substrates. The electrodes on the facing principal surfaces of the substrates are define an electrode gap therebetween such that electrical biasing of the electrodes simultaneously modifies the optical and electrode gaps.
Abstract:
The present disclosure is directed to a system and method to render spatially uniform memory colors when images printed with CMYK primaries are not rendered uniformly due to output device quality errors. The disclosed method uses an array of sensors to scan a test image. Colors of interest are printed at the desired location first and then adjusted (iterated) to achieve a desired output quality. Iterations are carried out on the image on desired memory colors at the spatial resolution available in the measurement system. Colors of pixels are modified based on position where the pixels will be rendered, thereby compensating for any position/process related differences. Also disclosed is a process for incorporating modified memory colors before rendering, and the extension of memory color concepts to adjust colors for the uniform blocks (not edges), with uniformity defined by user definable thresholds.
Abstract:
Printing occurs when a marking engine deposits ink on a substrate to produce a pattern. The printed pattern can differ from the desired pattern when the marking engine is out of adjustment, the substrate and ink do not interact optimally, or for other reasons. A tone reproduction curve can be used to adjust the pattern or the marking engine so the printed pattern and desired pattern are similar. Another effect of printing is that contours can appear. Contouring can be reduced if a smooth tone reproduction curve is used. Aspects of the embodiments address limitations and flaws in the prior art by using a smoothing parameter and a smoothing matrix to produce TRCs that minimize contours.
Abstract:
Tone reduction curves are utilized to map an input value to an output value. A tone reduction curve is normally produced by an algorithm that fits a curve to a series of knots. Knots can be determined from calibration data. Printing a calibration patch pattern yields a target patch pattern. The desired reflectances of the calibration patches and the measured reflectances of target patches can be used as calibration data. The series of knots can also include a highlight knot and a shadow knots so that the tone reduction curve functions better in the highlight and shadow regions.
Abstract:
To generate a reference database for a particular sensor in a multiple LED spectrophotometric system with a reduced number of test measurements taken from training samples, a first set of reflectance reference measurements are generated from a test target on to a reference sensor from a plurality of different LED emissions. A first spectral reconstruction reference matrix is computed comprising an operational characterization of the reference sensor from the first set of reflectance reference measurements. A second set of reflectance reference measurements from the test target is generated from a second subject sensor whose operation is to be personalized by the objective reference database. The second set of reflectance reference measurements are less in number than the first set. A second reconstruction matrix is computed comprising an operational characterization of the subject sensor from the second set of measurements. The second reconstruction matrix is adjusted by relating the second set of reflectance measurements to a set of corresponding reflectance measurements of the reference sensor, whereby the adjusting of the second matrix comprises computing an optimal solution spectral reconstruction matrix for the second sensor. The reference database is generated from the optimal solution spectral reconstruction matrix.
Abstract:
What is disclosed is a method for maintaining consistent color output across printers even when the inline sensors have differences in accuracy due to various technical and environmental factors. A spectrophotometer is used to measure the color quality of printed references. Adjustments are then iteratively made until reference charts of desired color quality are obtained. The printed reference allows one to achieve relatively high system performance by removing sensor inaccuracies. Using the printed reference measured by the inline sensor control systems of each machine are calibrated. At customer sites and at suitable intervals, a reference document can be read using the inline sensor on a reference machine and any differences from expected values can be calibrated out. The present method is also applicable to other color management functions such as memory color and automatic profile generations using inline/offline sensors and can be used for determining reference values while calibrating control systems of printers over a wide range of applications.
Abstract:
Spectrophotometer color measurement with a target illumination system and a reflected illumination sensing system where the target surface is variably spaced from said spectrophotometer. Color correction calibration information corresponding to color measurements for known different spacings of a test target surface from the spectrophotometer are obtained and stored. In use, the spacing of the actual target surface from the spectrophotometer is measured to provide a target spacing information signal. That signal is automatically combined with the stored color correction calibration information for the corresponding distances to provide at least partial correction of color measurement errors of the spectrophotometer for variable spacing of the target surface relative to the spectrophotometer even with low cost fixed focus optics. The spectrophotometer output can be so corrected by changing the target illumination, such as by LED pulse width changes, and/or by corrective adjustment of the measured reflectances.
Abstract:
A low cost spectral camera may include a multiple Fabry-Perot cavity filter with silicon photodetectors distributed one beside another in a two-dimensional matrix fashion. Each cavity may be designed to capture a pixel from an image. The two-dimensional fabry-perot array may function as a sensor to capture an image in spectral form. Spectral information may be obtained to generate spectral displays.
Abstract:
Methods and systems in an image processing device for controlling colors that are located external to a gamut are disclosed. A plurality of color values can be automatically provided as input to said image processing device, wherein said image processing device is under a control of a particular dimensional order, typically a three-dimensional order, but alternatively can be a two-dimensional order. Next, an operation can be performed dynamically determining which color value among the plurality of color values has attained a gamut limit. Thereafter, the particular dimensional order can be automatically reduced, thereby providing improved control for colors that are located external to said gamut. The plurality of color values analyzed is generally associated with three colors—cyan, magenta, and yellow.
Abstract:
This disclosure relates generally to methods and systems for color management in image/text printing or display systems, and more particularly to a system and method for automatically achieving spot color production through use of a plurality of gain matrices per spot color in determining spot color coordinates. Furthermore, this disclosure provides a means for mapping out-of-gamut target spot colors substantially near a boundary of the gamut of an image output device, such as a printer or display.