摘要:
Techniques are disclosed for correcting the exposure of a digital image. An exposure predictor may be generated based on a set of images for which ground truth data are known. After identifying an optimal set of features, the exposure of the digital image may be corrected by extracting values of the selected optimal features from the image, using the predictor to predict a desired exposure correction for the image, and correcting the exposure of the image by the predicted desired amount. Exposure correction is based on a model that relates intensity of light in the world to the RGB digits of the digital image. The model comprises a gamma function that models the response of a typical monitor and a S-shaped curve that compresses the large dynamic range of the world to the small dynamic range of the RGB digit space.
摘要:
Techniques are disclosed for performing color correction in a color printer. An RGB test image is printed to produce a printed calibration image. Colors in the printed calibration image are measured and compared to expected color values. A color corrector generates a printer lookup table (LUT) based on this comparison. The LUT may be generated based on models of the printer's print engine and previous LUTs. The color corrections are applied to subsequent print jobs to improve the quality of color output. Color measurement and correction may be performed using a closed-loop system contained within the printer that includes a color measurement device (such as a scanner) and a computer.
摘要:
Techniques are disclosed for correcting the exposure of a digital image. An exposure predictor may be generated based on a set of images for which ground truth data are known. After identifying an optimal set of features, the exposure of the digital image may be corrected by extracting values of the selected optimal features from the image, using the predictor to predict a desired exposure correction for the image, and correcting the exposure of the image by the predicted desired amount. Exposure correction is based on a model that relates intensity of light in the world to the RGB digits of the digital image. The model comprises a gamma function that models the response of a typical monitor and a S-shaped curve that compresses the large dynamic range of the world to the small dynamic range of the RGB digit space.
摘要:
Techniques are disclosed for correcting the exposure of a digital image. An exposure predictor may be generated based on a set of images for which ground truth data are known. After identifying an optimal set of features, the exposure of the digital image may be corrected by extracting values of the selected optimal features from the image, using the predictor to predict a desired exposure correction for the image, and correcting the exposure of the image by the predicted desired amount. Exposure correction is based on a model that relates intensity of light in the world to the RGB digits of the digital image. The model comprises a gamma function that models the response of a typical monitor and a S-shaped curve that compresses the large dynamic range of the world to the small dynamic range of the RGB digit space.
摘要:
A thermal printer is disclosed which includes a plurality of thermal print heads, each of the plurality of thermal print heads being operable to print a distinct one of a plurality of colors. The plurality of thermal print heads may print output at a plurality of spatial resolutions. The thermal printer may include dot size varying means for varying perceived levels of color printed by the thermal printer by varying sizes of dots printed by the plurality of thermal print heads. The printer may perform various image processing steps on an image to be printed, such as tone scale adjustment, thermal history control, and common mode voltage correction, to improve the perceived quality of the printed image. The thermal printer may be incorporated into a digital photo-printing vending machine for printing images provided by a customer.
摘要:
A thermal printer is disclosed which includes a plurality of thermal print heads, each of the plurality of thermal print heads being operable to print a distinct one of a plurality of colors. The plurality of thermal print heads may print output at a plurality of spatial resolutions. The thermal printer may include dot size varying means for varying perceived levels of color printed by the thermal printer by varying sizes of dots printed by the plurality of thermal print heads. The printer may perform various image processing steps on an image to be printed, such as tone scale adjustment, thermal history control, and common mode voltage correction, to improve the perceived quality of the printed image. The thermal printer may be incorporated into a digital photo-printing vending machine for printing images provided by a customer.
摘要:
Techniques are disclosed for correcting the exposure of a digital image. An exposure predictor may be generated based on a set of images for which ground truth data are known. After identifying an optimal set of features, the exposure of the digital image may be corrected by extracting values of the selected optimal features from the image, using the predictor to predict a desired exposure correction for the image, and correcting the exposure of the image by the predicted desired amount. Exposure correction is based on a model that relates intensity of light in the world to the RGB digits of the digital image. The model comprises a gamma function that models the response of a typical monitor and a S-shaped curve that compresses the large dynamic range of the world to the small dynamic range of the RGB digit space.
摘要:
The input energies provided to a print head of a thermal printer are adjusted based on the temperature of a platen in the thermal printer. The platen temperature may be measured by a sensor or predicted by a platen temperature model. Such a model may derive the predicted platen temperature from an observed temperature of a heat sink in the thermal printer. A thermal history control algorithm may use the platen temperature, whether actual or predicted, to compensate for the platen temperature by adjusting the input energies.
摘要:
A method for controlling the print density of individual heating elements of a thermal print head array determines respective energy values for each heating element in response to image pixel data to be printed, multiplies determined energy values by a respective predetermined correction factor for one or more respective heating elements for improving print density consistency between individual heating elements, and dithers adjusted energy values from the step of multiplying as a function of adjacent image pixels.
摘要:
Techniques are disclosed for performing thermal history control in a thermal printer in which a single thermal print head prints sequentially on multiple color-forming layers in a single pass. Each pixel-printing interval may be divided into subintervals, which may be of unequal duration. Each sub-interval may be used to print a different color. The manner in which the input energy to be provided to each print head element is selected may be varied for each of the subintervals. For example, although a single thermal model may be used to predict the temperature of the print head elements in each of the subintervals, different parameters may be used in the different subintervals. Similarly, different energy computation functions may be used to compute the energy to be provided to the print head in each of the subintervals based on the predicted print head temperature.