JP2010252228A - Image processing apparatus, image processing program, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To identify a foreground and a background without designating both for each document even if luminance of the foreground is close to that of the background when printing a multi-gradation monochromatic image. <P>SOLUTION: After a color image is converted into a multi-gradation monochromatic image by the printer driver of a PC, in an image forming apparatus, a background object of luminance (g) is bitmap-expanded and written into an image memory and when a character object of luminance (f) is to be bitmap-expanded and written into the image memory, the computer determines whether or not "¾f-g¾<threshold (m)" is established. In the case of a positive determination, when f>g and g+m≤255 are established, (f) is changed into f=g+m. When f<g and g-m≥0 are established, (f) is changed into f=g-m. Further, when f>g and g+m>255 are established, (f) is changed into f=g-m, and when f<g and g-m<0 are established, (f) is changed into f=g+m. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image processing apparatus that automatically changes the gradation of a part of an object included in a multi-tone monochrome image, a program thereof, and an image forming apparatus including the apparatus.

  When a color image is printed in multi-tone (grayscale) monochrome, for example, the printer driver converts the three primary color RGB values for each drawing command supplied from the application through the OS into, for example, the luminance Y by the following equation, and PDL (Page description language) and supplied to the image forming apparatus.

Y = (2B + 9G + 5R) / 16 (1)
For this reason, for example, when an image in which a dark green character of R = 0, G = 142, B = 0 is overwritten on a red background of R = 255, G = 0, B = 0 is displayed, both the background and the character Y = It becomes 80, and the character cannot be read.

In the following Patent Document 1, a character border color corresponding to a combination of a character color and a background color is set in advance, and further, a character and a background are specified in advance, and each value of the RGB values of both is determined by a computer. A configuration is disclosed in which it is determined whether or not all the differences are smaller than a set value, and when a positive determination is made, the character is outlined with the preset color.
JP 2006-186485 A

  However, in this patent document 1, it is necessary to designate a character and a background for each document. Further, this concept cannot be applied when a color image is printed in multi-tone monochrome. Such a problem also occurs when the foreground is other than a character and when a color image is displayed on a display device in multi-tone monochrome.

  In view of such problems, the object of the present invention is to specify both the foreground and the background without specifying the foreground and the background for each original even when the foreground and the background are close in brightness when printing a multi-tone monochrome image. An image processing apparatus and program for the same, and an image forming apparatus including the apparatus.

According to a first aspect of the present invention, an image processing apparatus that outputs a multi-tone monochrome image by overwriting at least a first object with a second object, includes storage means for storing a threshold value m, and includes a monochrome tone value. When the possible range is 0 to max and the monochrome gradation values of the first and second objects are g and f, respectively, the first object is bitmap-expanded and written to the image memory, and then the first Before the two objects are bitmap expanded and overwritten in the image memory, the computer
If it is determined whether or not | f−g | <m and an affirmative determination is made,
If f> g and g + m ≦ max, change f to f = g + m,
If f <g and g−m ≧ 0, f is changed to f = g−m.

In a second aspect of the image processing apparatus according to the present invention, in the first aspect, when the computer makes the positive determination,
If f> g and g + m> max, change f to f = g−m,
If f <g and g−m <0, f is changed to f = g + m.

  According to the configuration of the first or second aspect, the luminance value g of the first object on the rear surface is maintained, and the luminance value f of the second object on the front surface is interpreted while maintaining the magnitude relationship with the luminance g as much as possible. There is an effect that it is changed to a possible luminance value.

  FIG. 5 is a schematic hardware block diagram of the image forming system according to the first embodiment of the present invention.

  The image forming apparatus 10 is a multifunction machine capable of performing copying, printing, and FAX transmission / reception. In the image forming apparatus 10, a PROM 13, a DRAM 14, an operation panel 15, a printer 16, a scanner 17, a NIC (network interface) 18, and a FAX modem 19 are connected to a CPU 11 via an interface 12. In FIG. 5, a plurality of interfaces are shown as one block for simplification.

  The PROM 13 is, for example, a flash memory, and stores a general-purpose OS (operating system), an application including an image forming processing program, and various data including a threshold value m shown in FIG.

  The DRAM 14 is for a work area, and a buffer area 140, a display list area 141, and a frame area 142 as shown in FIG. 5B are secured by the image forming processing program.

  The operation panel 15 is used for inputting a setting value or an instruction and displaying a setting screen or a state. The user can change the threshold value m by operating the operation panel 15. The printer 16 is used for image input for copying and fax transmission. The scanner 17 includes a print engine, a paper feed unit, a conveyance unit, and a paper discharge unit. The bitmap data generated in the frame area 142 is supplied, and an electrostatic latent image is formed on the photosensitive drum based on the data. Then, this image is developed with toner, and the toner image is transferred to a sheet, fixed, and discharged. The NIC 18 is coupled to a PC (personal computer) 20 via a cable or a wireless communication medium. The FAX modem 19 is coupled to an arbitrary FAX apparatus via a public line network (not shown).

  A printer driver 21 is installed in the PC 20. The printer driver 21 is supplied with a drawing command via an OS from an application such as a word processor or a spreadsheet. The printer driver 21 converts each drawing command into a PDL (page description language) that can be interpreted by the image forming apparatus 10. At this time, the RGB value included as the attribute value of the drawing command is converted into, for example, the above formula (1). Convert to luminance value Y.

  Drawing commands (objects) described in PDL are stored in the buffer area 140 on the DRAM 14 via the NIC 18. The CPU 11 reads out characters, graphics or image objects described in PDL from the buffer area 140 according to the image forming program stored in the PROM 13, performs image processing, and supplies the result to the printer 16, thereby To form an image.

  The image forming apparatus 10 may be capable of color printing or only monochrome printing. For example, the image forming apparatus 10 may be capable of color printing, and may be configured to automatically perform monochrome printing when the remaining amount of C, M, or Y toner is less than a set value.

  FIG. 1 is a schematic flowchart of this image processing for one page. In the following, the step identification codes in the figure are shown in parentheses.

  (S0) Objects described in PDL are read from the buffer area 140 in the drawing order, converted into a display list (intermediate language), and stored in the area 141.

  (S1) For each drawing command of the display list, if the object is a character, the process proceeds to step S2, and if not, that is, if it is a graphic or an image, the process proceeds to step S3.

  The character object is generally a visible object that is overwritten last in the frame area 142 for each page (in the case of panda processing), that is, an object in the foreground (z-order is the maximum value).

  (S2) The gradation change process is performed assuming that the character object is the foreground object.

  FIG. 2 is a detailed flowchart of step S2.

  Here, each object should be printed based on the value of the luminance Y as much as possible. However, for characters, the user should be able to read it. Therefore, gradation change processing as shown below is performed.

  (S20) It is determined whether or not | f−g | <m. If an affirmative determination is made, the process proceeds to step S21; otherwise, the gradation changing process is terminated. Here, the luminance f is the luminance value of the character object or each character (assuming that there is no gradation and is uniform), and the luminance g is a frame region 142 corresponding to the position of the character object (for example, the character frame center point). Luminance Y at the upper position.

  (S21) If f> g, the process proceeds to step S22; otherwise, the process proceeds to step S24.

  (S22) If g + m ≦ 255 (FIG. 4B), proceed to step S23, otherwise (FIG. 4A) proceed to step S25. Here, 255 is the maximum value of the luminance Y.

  (S23) Substitute g + m for luminance f, that is, change luminance f to g + m, and end the gradation changing process.

  (S24) If g−m ≧ 0, proceed to step S25, otherwise proceed to step S23. Here, 0 is the minimum value of the luminance Y.

  (S25) Substitute g-m for luminance f, that is, change luminance f to g-m, and end the gradation changing process.

  By such processing, the value of the luminance Y of each object is maintained in principle, and the magnitude relationship between the character luminance f and the background luminance g is maintained as much as possible in relation to the background luminance g only for characters, and the user can Is changed to a legible luminance value.

  (S3) Returning to FIG. 1, the display list drawing command is expanded into a bitmap and overwritten in the frame area 142.

  (S4) The luminance Y is converted into the density D, and the density D is binarized (pseudo gradation) by the dither method.

  (S5) If an unprocessed object remains in the buffer area 140 for the same page, the process returns to step S0; otherwise, the process proceeds to step S6.

  (S6) The contents of the frame area 142 are supplied to the printer 16 to form an image on the paper.

  For example, as shown in FIG. 3A on the frame region 142, the character 31 is overwritten on the background 30, and if the luminance g of the background 30 and the luminance f of the character 31 are, for example, f = g before this overwriting. The luminance f is changed in gradation. That is, the character 31 cannot be identified as shown in FIG. 3B, but the value of the luminance f is changed to g + m or g−m by the processing of FIG. As shown in FIG. 5, the character 31 can be visually recognized, and the value of the luminance f is maintained in relation to the luminance g as much as possible.

  Although the preferred embodiment of the present invention has been described, the present invention includes various other modifications, and realizes other combinations of the components described in the above-described embodiments and the functions of the components. Other configurations using other configurations, and other configurations that would be conceived by those skilled in the art from these configurations or functions, are also included in the present invention.

  For example, in the above-described embodiment, the case where the gradation changing process is performed in the image forming apparatus 10 has been described. However, the printer driver 21 may perform this. The same applies to dumb printers that perform bitmap development in the printer driver 21.

  In the above embodiment, the gradation changing process is performed on a character object basis or on a character basis. However, the gradation changing process may be performed on luminance f and g on a pixel basis when developing a bitmap.

  In the above embodiment, the gradation change of the character object is automatically performed. However, the gradation change of the frontmost object is automatically changed, or the gradation change of the object designated in advance is automatically changed. It may be configured to be performed. The object may be specified abstractly such as “character object”, “character object having a size of 12 points or more”, and “frontmost object having a luminance value of 200 or more”.

  Further, the gradation changing process may be performed when previewing on the screen of the PC 20. That is, the present invention can be applied not only to printing but also to multi-tone monochrome image display.

  Furthermore, the present invention can also be applied to the case of a multi-tone monochrome image from the beginning.

3 is a schematic flowchart illustrating image processing for one page in the image forming apparatus. It is a detailed flowchart of step S2 in FIG. (A)-(C) is explanatory drawing regarding the gradation change of the process of FIG. (A) And (B) is explanatory drawing of the gradation change process of FIG. 1 is a schematic hardware block diagram of an image forming system according to Embodiment 1 of the present invention.

10 Image forming apparatus 11 CPU
12 Interface 13 PROM
14 DRAM
140 Buffer area 141 Display list area 142 Frame area 15 Operation panel 16 Printer 17 Scanner 18 NIC
19 FAX modem 20 PC
21 Printer driver 30 Background 31 Characters Y, f, g Brightness m Threshold

Claims (6)

An image processing apparatus that outputs a multi-tone monochrome image by overwriting at least a first object with a second object, includes a storage unit that stores a threshold value m, and a monochrome gradation value can take a range of 0 to max. Yes, when the monochrome gradation values of the first and second objects are g and f, respectively, the first object is bitmap-expanded and written to the image memory, and then the second object is bitmap-expanded Before overwriting the image memory, the computer
If it is determined whether or not | f−g | <m and an affirmative determination is made,
If f> g and g + m ≦ max, change f to f = g + m,
If f <g and g−m ≧ 0, change f to f = g−m.
An image processing apparatus. When the computer makes the positive determination,
If f> g and g + m> max, change f to f = g−m,
If f <g and g−m <0, change f to f = g + m.
The image processing apparatus according to claim 1.   The image processing apparatus according to claim 1, wherein the monochrome gradation values g and f are values at the same pixel position.   The image processing apparatus according to claim 1, wherein the second object is a character object, and the first object is a graphic object or an image object. An image processing apparatus according to any one of claims 1 to 4,
An image forming means for forming a monochrome image on the paper after the monochrome gradation value has been changed by the image processing apparatus;
An image forming apparatus comprising: In an image processing program for causing a computer to output at least a first object with a second object and outputting a multi-tone monochrome image, a monochrome gradation value can take a range of 0 to max. When the monochrome gradation values of two objects are g and f, respectively, after the first object is bitmap-developed and written in the image memory, before the second object is bitmap-expanded and overwritten on the image memory In addition,
It is determined whether or not | f−g | <m, and when an affirmative determination is made,
If f> g and g + m ≦ max, change f to f = g + m,
If f <g and g−m ≧ 0, f is changed to f = g−m.
An image processing program characterized by that.