Abstract: A halftone comprises a first halftone screen and a second halftone screen. The first halftone screen comprises a first plurality of amplitude modulated dots arranged according to a first plurality of rows, the first plurality of rows being orientated according to a first direction and comprising a first dot spacing. The second halftone screen comprises a second plurality of amplitude modulated dots arranged according to a second plurality of rows, the second plurality of row being orientated in a second direction and comprising a second dot spacing. The first direction and the second direction define an angle of 45 degrees or less and a ratio of the second dot spacing to the first dot spacing is less than one.

Abstract: A method of determining the velocity of relative displacement between a substrate and an image sensor, for example the velocity of displacement of a page relative to a scanner, involves imaging a reference pattern on the substrate, using the image sensor, while the relative displacement occurs between the substrate and the image sensor. The reference pattern includes plural crossing points marked at predetermined locations on the substrate, each crossing point formed of a first line portion crossing a second line portion. Locations in the image that correspond to the crossing points are compared to the predetermined locations on the substrate and the velocity of the relative displacement between the image sensor and the substrate is determined using relationships between the predetermined locations and the detected locations in the generated image.

Abstract: A system includes a structure module, graininess module, mottle module, and standard deviation (STD) module. The structure module is to identify a structure metric based on an input digital image, and remove a structured nonuniformity from the input digital image to produce a second input digital image. The graininess module is to identify a graininess metric based on the second input digital image. The mottle module is to identify a mottle metric based on the second input digital image. The STD module is to identify a STD metric that is to correspond to overall smoothness of the input digital image.

Abstract: A system includes a structure module, graininess module, mottle module, and standard deviation (STD) module. The structure module is to identify a structure metric based on an input digital image, and remove a structured nonuniformity from the input digital image to produce a second input digital image. The graininess module is to identify a graininess metric based on the second input digital image. The mottle module is to identify a mottle metric based on the second input digital image. The STD module is to identify a STD metric that is to correspond to overall smoothness of the input digital image.

Abstract: A halftone screen may be used to transform a continuous tone image into a halftone image. Determining the halftone screen may include determining a first halftone tile for a first gray level, selecting pixel locations and increasing the intensity of pixels at the locations to activate the pixels to form a second halftone tile for a subsequent gray level. A filtered image may be generated from the second halftone tile, and pixels from the filtered image may be used to generate the halftone screen.

Abstract: A halftone screen may be used to transform a continuous tone image into a halftone image. Determining the halftone screen may include determining a first halftone tile for a first gray level, selecting pixel locations and increasing the intensity of pixels at the locations to activate the pixels to form a second halftone tile for a subsequent gray level. A filtered image may be generated from the second halftone tile, and pixels from the filtered image may be used to generate the halftone screen.

Abstract: A method of determining the velocity of relative displacement between a substrate and an image sensor, for example the velocity of displacement of a page relative to a scanner, involves imaging a reference pattern on the substrate, using the image sensor, while the relative displacement occurs between the substrate and the image sensor. The reference pattern includes plural crossing points marked at predetermined locations on the substrate, each crossing point formed of a first line portion crossing a second line portion. Locations in the image that correspond to the crossing points are compared to the predetermined locations on the substrate and the velocity of the relative displacement between the image sensor and the substrate is determined using relationships between the predetermined locations and the detected locations in the generated image.