Facsimile and static presentation processing – Static presentation processing – Size – resolution – or scale control
Reexamination Certificate
1998-02-27
2001-12-25
Coles, Edward (Department: 2722)
Facsimile and static presentation processing
Static presentation processing
Size, resolution, or scale control
C358S001100, C358S401000, C358S450000, C358S451000, C382S268000, C382S269000
Reexamination Certificate
active
06333792
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image resolution conversion method for converting the resolution of an image by increasing or decreasing the number of pixels that express the image. More particularly, the present invention relates to a resolution conversion module that can be built in a printer driver in a host computer and implements the image resolution conversion method, and a printer driver with that module, and has as its object to change the resolution of image data on a computer in correspondence with the resolution of an output apparatus such as an ink-jet printer or the like. Furthermore, the present invention relates to various storage media that store an image processing program including the resolution conversion module.
In general, in computer systems, since the resolutions used are different between the input and output apparatuses, the input/output apparatus and computer main body, or the systems in correspondence with their purposes, images are often processed at different resolutions. Of such differences, the resolution difference between the computer main body or display, and printer is most frequently.
A program called a printer driver runs on a computer, and generates data to be printed by a printer and outputs a drawing command to the printer. The printer driver converts commands that are standardized among the respective OS's and are used for drawing characters, figures, and images into drawing commands that can be interpreted by each printer. In this case, the printer driver must take the difference between the processing resolution on the application program and the resolution at the printer into consideration. For example, when the application program manages data at 90 dpi, and that data is output by a printer having a resolution of 360 dpi, the printer driver must generate page data having pixels four times those of the original data in both the vertical and horizontal directions.
Serial printers represented by ink-jet printers, to which the present invention is especially suitably applied, have no PDL (page description language), and normally print upon receiving print commands based on bitmap data generated by printer drivers. Hence, such printer driver converts character and figure data expressed by vectors into bitmap data with an output resolution by directly mapping them on a memory to have the number of pixels corresponding to printer resolutions. As for image data which is already bitmap data, the printer driver converts them into bitmap data with an output resolution by changing their size by enlargement or reduction in correspondence with the output resolution.
There are various types of resolution conversion methods achieved by enlargement or reduction of bitmap data. For example, when enlargement is used, 0-th order interpolation that simply repeats pixels in correspondence with an enlargement factor, linear interpolation that fills pixels produced by enlargement on the basis of, e.g., the ratio of distances from the original pixel, a method of attaining optimal enlargement by switching various interpolation schemes depending on the layout state of surrounding pixels (Japanese Laid-Open Patent No. 7-105359), and the like are available.
However, the image processing in a printer driver has many limitations, and it is often impossible or difficult to install resolution conversion in the driver, since the individual schemes cannot directly cope with arbitrary magnifications including non-integer magnifications, since these schemes cannot cope with processing in units of arbitrary numbers of lines that may produce a discontinuity between neighboring bands in the output result, and so on. Such problems are serious in digital image filter-based image processing schemes that require surrounding pixels upon processing each pixel. However, in general, the digital image filter-based processing can assure higher image quality after processing than simple processing such as 0th-order interpolation that does not use any surrounding pixels.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an image resolution conversion method that can cope with arbitrary magnifications including non-integer magnifications with simple operation and sequence, and an image resolution conversion module that can implement the method.
It is another object of the present invention to provide an image resolution conversion method which can be efficiently installed in a printer driver using a standardized interface even if it has, especially, a digital filter-based enlargement/reduction method implemented as software on a computer, and an image resolution conversion module that implements the method.
It is still another object of the present invention to provide a printer driver installed with the image resolution conversion module.
It is yet another object of the present invention to provide a storage medium that stores a printer driver including the image resolution conversion module, an installation program, and an image processing program.
In order to achieve the above objects, according to the present invention, a resolution conversion module of the present invention is a resolution conversion module for converting a resolution of image data, comprising the steps of: receiving information representing resolutions before and after conversion from an external device; calculating a magnification or reduction value for each pixel of an original image before conversion on the basis of the received information; receiving information of a processing region, which is segmented with reference to an image size after conversion, from the external device; obtaining a region on the original image before conversion corresponding to the segmented processing region on the basis of the magnification or reduction values for pixels; passing information of the obtained region on the original image before conversion to the external device; receiving original image data of the obtained region from the external device; changing a size of the received original image data on the basis of the magnification or reduction values for pixels; and passing the data of the region after resolution conversion to the external device. Note that the information representing the resolutions before and after conversion represents sizes of image data before and after conversion, which are expressed by the numbers of pixels.
The resolution conversion module is installed in an image processing program. The image processing program is a printer driver, the resolution after conversion is a resolution of a printer, and the processing region which is segmented with reference to the image size after conversion is a band region. The magnification or reduction value for each pixel of the original image before conversion include a combination of an integer multiple or a fraction of an integer so that a sum of magnification or reduction values for a plurality of pixels yield magnification of the resolution before and after conversion. The information of the segmented processing region includes a start point position and size of the region. The step of obtaining the region on the original image includes the steps of: adjusting the start point and size using the number of pixels required for resolution conversion; and adjusting the start point and size of the region in consideration of end portions of the original image. The information of the obtained region on the original image includes a start point position and size of the region. The step of changing the size of the image includes the steps of: receiving image data in units of lines; holding the received image data in correspondence with the number of lines required for changing the size; discarding image data for the line which has become unnecessary and updating the image data to image data for a new line; and outputting processed data in units of lines.
A printer driver according to the present invention is a printer driver installed with a resolution conversion module for image data, the resolution con
Canon Kabushiki Kaisha
Coles Edward
Fitzpatrick ,Cella, Harper & Scinto
Lamb Twyler
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