Method and apparatus for high quality printing of non-saturated colored text and lines
View Patent ↗An embodiment implements a methodology for printing non-saturated text and lines in a way that removes the jagged edge problem. An embodiment uses a combination of two screens, e.g. AM screening and applying pure color. For example, according to the embodiment, the closer to the edge from the interior of text or lines, the less amplitude modulation half toning is applied and the more actual color or contone is applied. A particular algorithm for determining and using a blending parameter is provided.
1. A computer-implemented method for printing non-saturated text or lines, comprising the steps of:
determining a distance, D, within which a pixel is considered close to an edge of the non-saturated text or line, wherein one end of D is referred to as D Max and the opposite end of D is referred to as D MIN ;
providing a blending parameter, α, that is equal to zero at D MIN and is equal to one at D MAX ;
for each pixel inside the non-saturated text or line:
determining a distance from the pixel inside the non-saturated text or line to the edge of the non-saturated text or line;
in response to determining that the distance is less than or equal to D from inside the non-saturated text or line to the edge, assigning a value to α that is between zero and one or equal to zero if the distance is D MAX or one if the distance is D MIN ;
in response to assigning the value to α, evaluating, using α, a combination of an amount of a first screen and an amount of contone; and
in response to evaluating the combination, printing said pixel using said combination on an eletrophotographic printer;
wherein the steps of the method are performed by one or more computing devices.
2. The method of claim 1 , wherein said first screen is an AM screen.
3. The method of claim 1 , wherein the combination is:
α[the first screen]+(1−α)[the contone].
4. The method of claim 1 , wherein said printing said pixel using said combination further comprises:
in response to evaluating the combination, determining an approximation of said combination to a particular level from a set of levels of color that is provided by said eletrophotographic printer.
5. The method of claim 1 , wherein the blending parameter may be configured by a user and wherein said configured blending parameter overrides the step of assigning a value to α.
6. The method of claim 1 , wherein the length of D is three pixels.
7. An apparatus for printing non-saturated text or lines, comprising:
at least one processor coupled to at least one memory;
said at least one processor configured for determining a distance, D, within which a pixel is considered close to an edge of the non-saturated text or line, wherein one end of D is referred to as D MAX and the opposite end of D is referred to as D MIN ;
said at least one processor configured for providing a blending parameter, α, that is equal to zero at D MIN and is equal to one at D MAX ;
said at least one processor configured for executing the following steps for each pixel inside the non-saturated text or line:
determining a distance from the pixel inside the non-saturated text or line to the edge of the non-saturated text or line;
in response to determining that the distance is less than or equal to D from inside the non-saturated text or line to the edge, assigning a value to a that is between zero and one or equal to zero if the distance is D MAX or one if the distance is D MIN ;
in response to assigning the value to a, evaluating, using a, a combination of an amount of a first screen and an amount of a contone; and
in response to evaluating the combination, printing said pixel using said combination on an eletrophotographic printer.
8. The apparatus of claim 7 , wherein said first screen is an AM screen.
9. The apparatus of claim 7 , wherein the combination is:
α[the first screen]+(1−α)[the contone].
10. The apparatus of claim 7 , wherein said at least one processor is further configured for:
in response to evaluating the combination, determining an approximation of said combination to a particular level from a set of levels of color that is provided by said eletrophotographic printer when printing said pixel using said combination.
11. The apparatus of claim 7 , wherein the blending parameter may be configured by a user and wherein said configured blending parameter overrides the step of assigning a value to a.
12. The apparatus of claim 7 , wherein the length of D is three pixels.
13. A non-transitory computer-readable storage medium storing one or more sequences of instructions for printing non-saturated text or lines, which instructions, when executed by one or more processors, cause the one or more processors to carry out the steps of:
determining a distance, D, within which a pixel is considered close to an edge of the non-saturated text or line, wherein one end of D is referred to as D MAX and the opposite end of D is referred to as D MIN ;
providing a blending parameter, α, that is equal to zero at D MIN and is equal to one at D MAX ;
for each pixel inside the non-saturated text or line:
determining a distance from the pixel inside the non-saturated text or line to the edge of the non-saturated text or line;
in response to determining that the distance is less than or equal to D from inside the non-saturated text or line to the edge, assigning a value to α that is between zero and one or equal to zero if the distance is D MAX or one if the distance is D MIN ;
in response to assigning the value to α, evaluating, using α, a combination of an amount of a first screen and an amount of a contone; and
in response to evaluating the combination, printing said pixel using said combination on an eletrophotographic printer.
14. The non-transitory computer-readable storage medium of claim 13 , wherein said first screen is an AM screen.
15. The non-transitory computer-readable storage medium of claim 13 , wherein the combination is:
α[the first screen]+(1−α)[the contone].
16. The non-transitory computer-readable storage medium of claim 13 , further causing the one or more processors to carry out the steps of:
in response to evaluating the combination, determining an approximation of said combination to a particular level from a set of levels of color that is provided by said eletrophotographic printer, when printing said pixel using said combination.
17. The non-transitory computer-readable storage medium of claim 13 , wherein the blending parameter may be configured by a user and wherein said configured blending parameter overrides the step of assigning a value to α.
18. The non-transitory computer-readable storage medium of claim 13 , wherein the length of D is three pixels.