Facsimile and static presentation processing – Natural color facsimile – Specific image-processing circuitry
Patent
1993-04-19
1994-12-06
Coles, Sr., Edward L.
Facsimile and static presentation processing
Natural color facsimile
Specific image-processing circuitry
358523, 358501, 358456, 358298, H04N 146
Patent
active
053716167
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method for converting a tone of a picture made use in plate-making process for producing reproduced pictures such as printed pictures, various pictorial hard copies of high quality. This invention is, more specifically, concerned with a novel tonal conversion method for a picture employed when a reproduced picture of a half tone is produced from a color photographic picture of a continuous tone as an original picture.
It is a matter of course that when a color photographic picture in a continuous tone is used as an original picture to make a reproduced picture such as a printed picture by using a color scanner as a plate-making device or to output a pictorial hard copy of a high quality by using a scanner or a high-performance printer, the continuous tone of the original picture should be converted into a halftone expressing a reproduced picture.
A term "tonal conversion of a picture" mentioned above means that density information of each pixel of an original picture is converted into density information of a reproduced picture system.
There have been known in a field of production of a reproduced picture various reproducing techniques (i.e., density representing techniques) to reproduce the density information of an original on a reproduced picture, in any one of which the tone of the original picture is converted.
The tonal conversion closely relates to conversion of density information of pixels along with conversion of color tone of pixels. The detail of this will be stated later.
Typical techniques employed currently to represent density of a reproduced picture are as follows: pixel is changed according to a size of a dot (as called "dot area % value"). Namely, a covering rate of a given pixel is changed by varying a size of a dot to reproduce the density information of an original picture on a printed picture.
This technique is referred "a multiple valued dot area tonal representation", applied to ink jet printers, thermally molten transfer printers (thermal printers), and the like, in addition to a printed picture producing device. changed by changing an arrangement of dots of the same size, as contrasted with the above multiple valued dot area technique where a size of a dot is changed. This technique is called "binary valued dot area tonal conversion representation", applied in the same field such as thermally molten transfer printers, ink jet printers, and the like. given size is changed. This is based on the same principle as the reproducing system of a continuous density seen in general photographic materials. This technique is referred "a direct density tonal representation", applied in sublimation type thermal transfer printers (sublimation type printers) and the like.
As stated above, various reproducing techniques are used to produce reproduced pictures such as printed pictures, hard copies outputted from a high-performance printers and the like from original pictures of a continuous tone. Incidentally, a term "reproduced picture" referred in this invention should be interpreted in the broadest sense including printed pictures and outputted hard copies of a high-performance printer. It is a material subject in such techniques to faithfully reproduce, gradation and color tone of an original picture in a reproduced picture, with operational regularlity.
It is, however, the present condition that the subject relating to reproducibility, mentioned above, cannot be rationally overcome in spite of recent remarkable improvements in the filed of picture reproduction.
The main cause of the present condition lies in that, in a technique to faithfully reproduce a tone (including gradation and color tone) of an original picture on a reproduced picture or in a technique to control (correct or alternate) the tone of an original picture, a tone non-linearly converting and processing technique (i.e., a tonal conversion technique of a picture or a tonal conversion method of a picture) applied relating to a density area of a picture lacks theory
REFERENCES:
patent: 5072305 (1991-12-01), Numakura et al.
Numakura Iwao
Numakura Takashi
Coles Sr. Edward L.
Lee Fan
Yamatoya & Co., Ltd.
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