The present invention relates to a printing technology.
With sophisticated information processing technologies, a multiplicity of information devices are used in a variety of scenes in the society. Then, an enormous quantity of information is printed by printers. Particularly over the recent years, images captured by digital cameras etc are printed by color printers in the great majority of cases. The color print involves especially a large quantity of toner consumption.
Accordingly, a running cost that depends upon the toner consumption is not ignorable nowadays. This being the case, a scheme for saving the toners has hitherto been proposed.
What is known as a toner save technology for this purpose is a method of extracting an outline of character/graphic data after being developed on, e.g., a bitmap memory. This method serves to restrain a quantity of toners by diminishing a dot size of an internal area or the outline of the character/graphic data (which may be called a prior art 1).
Another known method is that the toner quantity is restrained by thinning out at a fixed ratio the data after similarly being developed on the bitmap memory (wherein the dots occupying a fixed ratio per unit area are removed off) (which may be called a prior art 2). Alternative known method is that the toner quantity is restrained by increasing at a fixed ratio the brightness of the print data as a whole (which may be called a prior art 3).
These prior arts, however, have no scheme of distinguishing between categories of the print data such as characters, graphic, images etc, and the toner save is carried out by the same method with respect to all pieces of print data. Therefore, the toner save optimal to every category of the print data was not actualized. Then, as a result, the toner save function described above proved poor of a print quality and was therefore unusable except at a print level for trial.
The prior art 1 is effective in, for example, the characters and graphics with no expression of halftones (intermediate colors), but raises a problem of being unable to functioning effectively in the characters and graphics involving the expressions of images and halftones. This is because it is difficult to extract the outline of the character and graphic containing the halftone expression.
Particularly in the case of the color print, the processing is effected for four colors Y (yellow), M (magenta), C (cyan) and K (black), and hence the halftone expression is indispensable for the character and graphic. The prior art 1 was not therefore applicable to the color print.
Further, the prior art 2 also has problems in a pattern having a periodicity in the print data and in a dot pattern. Namely, in the case of thinning out the above print data at the fixed ratio, an irregularity in period due to interference with the pattern period becomes conspicuous, which did not lead to a preferable result of printing.
Moreover, the prior art 3 has a possibility in which sharpness (clearness) conceived important in terms of an image quality might be deteriorated because of increasing the brightness of the character/graphic/image as a whole. Further, when applied to a small character and a fine line, a solid line might be printed as if a dotted line and might appear lighter than a brightness improving rate specified.
Further, there has seen a leap in improvements of the quality and performance of a color printer over the recent years, and a printed result having substantially the same quality as a photograph has been acquired. There is provided a product capable of outputting such a high-quality print at the same printing speed as that of a monochromatic printer (that outputs a binary monochrome pattern and will hereinafter be simply termed a monochrome printer or a monochrome machine).
Furthermore, a product price rapidly decreases, and there is a possibility wherein the market shares of the monochrome printers and color printers will be reversed several years later. For attaining this share-turnabout, a print cost per page is a bottleneck.
A cost for using the toners for a color print is higher than a cost for a monochrome print. Then, if print target data are categorized as a material for presentation that contains natural images and background colors, a print area increases. Therefore, the print of such data involves a further increase in toner spent quantity.
On the other hand, if a large quantity of prints can be attained owing to a decrease in price of the main unit of the printer product, there might be a strict request for a running cost in terms of purchasing the printer product.