Image resolution conversion using a plurality of image registrations

Claim 3

The method of claim 1, further comprising the step of prefiltering the input image, said prefiltering step including the steps of interpolating, and image smoothing to prepare the input image for said defining step.

Claim 4

The method of claim 1, further comprising the step of quantizing the depth of each output pixel to the second depth.

Claim 5

The method of claim 1, wherein said defining step comprises the step of using a greatest common divisor (GCD) between the first resolution of the input pixels and the second resolution of the output pixels to define an input tile and an output tile.

Claim 6

The method of claim 1, wherein said calculating step calculates in parallel each output pixel in the set of spatial registrations.

Claim 7

The method of claim 1, wherein said step of forming the output pixel values comprises the step of filtering a median value of the distribution of the set of output pixels.

Claim 8

An image processing apparatus in a reproduction system, comprising: an image input terminal emitting, as electrical signals, input images having a plurality of input pixels with a resolution of K pixels per unit length by L pixels per unit length with each input pixel defined at a depth b representing one of b optical densities; a first storage device for receiving the electrical signals from said image input terminal; means, coupled to said first storage device, for performing input interpolation and smoothing to prepare the input images for processing; first processing means, in communication with said performing means, for converting the resolution of input pixels to output pixels having a resolution of M pixels per unit length by N pixels per unit length, determining for each output pixel, a plurality of possible phases and first registrations of the output pixels with respect to the input pixels, each first registration providing a possible optical density value for the output pixels, for each of the possible first registrations of the output pixels, and determining a plurality of second registrations that are spatially offset from the first registrations; means, coupled to said first processing unit, for forming a distribution of the plurality of second registrations for each output pixel; second processing means, coupled to said forming means, for determining for each output pixel, a value for the output pixel that is a median value of the distribution of the plurality of second registration values; means, coupled to said second processing unit, for quantizing the depth of each output pixel to the depth d; a second storage device for receiving each output pixel from the quantizing means and storing as an electrical signal each output pixel; and an image output terminal adapted to receive the electrical signals from said second storage device.

Claim 9

An image processing apparatus in a reproduction system, comprising: an image input terminal emitting, as electrical signals, input images having a plurality of input pixels with a resolution of K pixels per unit length by L pixels per unit length with each input pixel defined at a depth b representing one of b optical densities; a first storage device for receiving the electrical signals from said image input terminal; means, coupled to said first storage device, for performing input interpolation and smoothing to prepare the input images for processing; first processing means, in communication with said performing means, for converting the resolution of input pixels to output pixels having a resolution of M pixels per unit length by N pixels per unit length, determining for each output pixel, a plurality of possible phases and first registrations of the output pixels with respect to the input pixels, each first registration providing a possible optical density value for the output pixels, for each of the possible first registrations of the output pixels, and determining a plurality of second registrations that are spatially offset from the first registrations; means, coupled to said first processing unit, for forming a distribution of the plurality of second registrations for each output pixel; second processing means, coupled to said forming means, for determining for each output pixel, a value for the output pixel that is a median value of the distribution of the plurality of second registration values; means, coupled to said second processing unit, for quantizing the depth of each output pixel to the depth d; a second storage device for receiving each output pixel from the quantizing means and storing as an electrical signal each output pixel; and an image output terminal adapted to receive the electrical signals from said second storage device.

Claim 10

The image processing apparatus of claim 7, wherein said first processing means forms an input tile and an output tile that are defined by a greatest common divisor (GCD), the GCD providing a periodically repeating mapping that spatially offsets the input tile and the output tile to define the conversion between the input image and the output image.

Claim 11

The image processing apparatus of claim 8, wherein said periodically repeating mapping is spatially offset by altering the input tile and the output tile mapping defined by the GCD to form a new periodically repeating mapping.

Claim 12

The image processing apparatus of claim 7, wherein each output pixel further comprises a linear combination of input pixels.

Claim 13

The image processing apparatus of claim 10, wherein the linear combination of input pixels is defined using area mapping.

Claim 14

The image processing apparatus of claim 7, wherein said first processing means processes the plurality of output pixels in parallel.

Claim 15

The image processing apparatus of claim 7, wherein said second processing means comprises a median filter for determining the output pixel value from the distribution of the plurality of output pixels.

Claim 16

The image processing apparatus of claim 7, wherein said image input terminal comprises a scanner.

Claim 17

The image processing apparatus of claim 7, wherein said image output terminal comprises a printer.