JP4386779B2 - Thermal storage correction device, thermal storage correction method, and thermal recording device - Google Patents

Description

  The present invention relates to a thermal storage correction device that is used in a thermal head of a thermal printer and corrects output image quality degradation due to the effect of thermal storage, and a thermal recording apparatus including the thermal storage correction device.

  A thermal printer is a device that heats the back of an ink ribbon stacked on a recording paper with a thermal head and thermally transfers the ink on the recording ribbon to the recording paper for printing. The ink ribbon is a thermal transfer sheet having a heat-meltable colored ink layer, and the recording paper is an image receiving sheet such as paper or a plastic sheet.

  The thermal head is composed of a plurality of heating resistors formed in a line on the substrate. The thermal printer includes a plurality of ink ribbons, and color printing can be performed by superimposing and transferring inks of a plurality of colors of ink ribbons at the same position on the recording paper. For example, a plurality of ink ribbons are installed in a rotating manner, and the ink ribbon for performing thermal transfer is moved to the position of the thermal head. The recording paper transport device transports the recording paper to the position of the thermal head, which is the printing position, and prints a predetermined printing range of the recording paper.

  When image data is input to the thermal head, energy corresponding to the image data is applied to the thermal head, and an image is output to the recording paper. However, in a thermal recording apparatus that performs output using a thermal head, if printing continues, the temperature of the heating resistor of the thermal head rises and is affected by the heat stored, and for example, certain image data is input. However, the print recording density gradually increases. For this reason, the density of the output image may become non-uniform or the outline of the image may be blurred. Therefore, in order to obtain an image with stable image quality, it is necessary to control the energy applied to the thermal head in accordance with the temperature rise.

  Conventionally, there has been a thermal recording apparatus in which a temperature detection element is provided in a thermal head, and the printing pulse width and energization current are controlled from the temperature of the entire thermal head. There has also been proposed a thermal recording apparatus that includes a circuit for calculating past printing history for each heating resistor of the thermal head and controls the printing pulse width and current value in units of pixels.

Further, as a method of performing temperature correction of the thermal head, a method of performing pixel correction calculation in consideration of heat storage history of a plurality of peripheral pixels for one pixel, and printing for each line after the pixel correction calculation is completed. Yes (Patent Document 1).
JP-A-5-169709

  However, in a thermal recording apparatus that controls the energy applied to the thermal head by detecting the temperature of the thermal head with the temperature detection element, the temperature of the heating resistor is effective even when printing at a relatively low speed. Since there is a time delay until the temperature is reflected on the temperature of the substrate on which the temperature detection element is mounted, the response speed is limited, which is not suitable for a high-speed printing thermal recording apparatus.

  In addition, the thermal recording device that calculates the past print history for each heating resistor and controls the print pulse width and current value in units of pixels only considers the thermal history of the same pixel alone, and has an actual effect. It did not consider the thermal history of the surrounding pixels.

  In addition, in the case of performing thermal head temperature correction taking into account the thermal storage history of a plurality of peripheral pixels, for example, if optimal thermal storage correction is performed on the contour portion (edge) of the image to be printed, thermal storage correction other than the contour portion is performed. Insufficient and excessive energy causes ink ribbon breakage and wrinkles, and shortens the life of the thermal head. Further, if the optimum heat storage correction is performed on a portion other than the contour portion, it becomes inappropriate as the heat storage correction on the contour portion, and the print may be faded due to insufficient energy.

  The problem to be solved by the present invention is that, in the conventional heat storage correction method, an inappropriate correction occurs depending on the image portion of the image to be printed.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a heat storage correction device that performs heat storage correction processing of a thermal head in accordance with the characteristics of an image to be printed.

In order to achieve the above-described object, a first invention is a thermal storage correction apparatus that performs thermal storage correction by image data processing on original image data of a screen to be printed in a thermal recording apparatus having a thermal head, wherein the original image A first contour extracting means for extracting a contour portion of data; a gradation converting means for adjusting the brightness of the original image data other than the contour portion extracted by the first contour extracting means; and the original image data. On the other hand, an adjacent history correction unit that performs thermal history correction in consideration of peripheral pixel data of each pixel and the contour portion extracted by the first contour extraction unit, the thermal history is corrected by the adjacent history correction unit. Second contour extracting means for extracting the contour portion of the image data corrected for the image, image data other than the contour portion whose brightness has been adjusted by the gradation converting means, and the second contour extraction An accumulated-heat correction apparatus characterized by having an image synthesizing means for synthesizing the corrected contours heat history extracted by means.

  The adjacent history correction unit corrects the pixel value of the target pixel by weighting the pixel values of the peripheral pixels of one target pixel to remove the influence of heat storage. Adjacent history correction is performed on all image data.

The first contour extraction means preferably extracts a contour portion of the original image data using a predetermined contour extraction pattern. As the contour extraction pattern, it is desirable to set an optimum contour extraction pattern for contour extraction according to the characteristics of the original image.
The second contour extracting means extracts the contour portion of the image data obtained by performing the thermal history correction by the adjacent history correcting means on the original image data. At this time, the contour extracted by the first contour extracting means is extracted. Use data.
The contour extracting means extracts a contour portion of the image data. The optimum heat storage correction amount for the contour portion needs to be weaker than the heat storage correction amount for portions other than the contour portion.

  The gradation conversion means performs the gradation of the image data, that is, the lightness conversion of the image by multiplying all the pixel values constituting the image data by the ratio of the designated gradation.

The image synthesizing unit synthesizes the image data of the portion other than the contour whose brightness is adjusted by the gradation converting unit and the image data of the contour portion after the thermal history correction extracted by the second contour extracting unit, The image data for printing which reduces the influence of heat storage is obtained.

The heat storage correction processing apparatus according to the first invention includes, as image data processing means for a screen to be printed, an adjacent history correction means, first and second contour extraction means, gradation conversion means, and image composition means. The image data for printing is obtained and provided to the thermal head of the thermal recording apparatus.

A second invention is a thermal storage correction method for performing thermal storage correction by image data processing on original image data of a screen to be printed in a thermal recording apparatus having a thermal head, wherein the contour portion of the original image data is extracted. Contour extracting step, gradation converting step for adjusting the brightness of the original image data other than the contour portion extracted by the first contour extracting step, and peripheral pixels of each pixel with respect to the original image data Using an adjacent history correction step for performing thermal history correction considering data and the contour portion extracted by the first contour extraction step, a contour portion of image data in which the thermal history is corrected by the adjacent history correction step is obtained. The second contour extraction step to be extracted, the image data other than the contour portion whose brightness has been adjusted by the gradation conversion step, and the heat history extracted by the second contour extraction step are corrected. An image combining step of combining the contour portion was a accumulated-heat correction method characterized by having a.

A third invention is a thermal recording apparatus having a thermal head, an image input means for acquiring and recording original image data of a screen to be printed, and a first contour extraction means for extracting a contour portion of the original image data And gradation converting means for adjusting the brightness of the original image data other than the contour portion extracted by the first contour extracting means, and peripheral pixel data of each pixel is considered for the original image data A second part that extracts a contour portion of image data in which the thermal history is corrected by the adjacent history correction unit, using an adjacent history correction unit that performs thermal history correction and the contour portion extracted by the first contour extraction unit. The contour extraction unit, the image data other than the contour portion adjusted by the gradation conversion unit, and the contour portion corrected by the thermal history extracted by the second contour extraction unit. An image synthesizing means, a thermal recording apparatus characterized by having a printing means for printing sends image data obtained in said thermal head by the image synthesizing means.

  ADVANTAGE OF THE INVENTION According to this invention, the thermal storage correction | amendment apparatus which performs the thermal storage correction | amendment process of the thermal head according to the characteristic of the image of a printing object can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration of a thermal printer 1 according to the present embodiment.

(1. Configuration)
(1-1. Configuration of Thermal Printer 1)
The thermal printer 1 is a device that heats the back of an ink ribbon stacked on a recording paper with a thermal head, and thermally transfers the ink on the ink ribbon onto the recording paper for printing. The thermal printer 1 includes an image input unit 5, a storage unit 7, a control unit 9, a printing unit 11, and the like, which are connected by a bus 13.

  Image data 3 to be printed is input to the image input unit 5. The storage unit 7 records input image data 3, temporarily stored data being calculated, corrected image data 3, correction processing parameters, and the like. The control unit 9 is a CPU or the like, and instructs the image input unit 5 to take in the image data 3, performs correction calculation processing of the image data 3, sends the processed image data to the printing unit 11, and issues a printing instruction. .

  Although not shown, the printing unit 11 includes a thermal head composed of a plurality of heating resistors formed in a row on a substrate, an ink ribbon, recording paper, a thermal head drive unit, and the like. When image data to be printed is sent in response to an instruction from the control unit 9, the printing unit 11 applies energy corresponding to the pixel value to the thermal head and outputs an output image 15. If the pixel value is large, the print recording density is high. Conversely, if the pixel value is small, the print recording density is low.

  FIG. 2 is a diagram illustrating the configuration of the thermal printer 1 in FIG. 1 and the relationship between the processing contents. The image input unit 5 performs image reading 17 of the image data 3, records the read image in the image memory 23 of the storage unit 7, and sends it to the control unit 9 at the same time. The control unit 9 performs image processing 19 on the image data 3.

  As will be described in detail later, the image processing 19 is processing steps such as contour extraction processing, gradation conversion processing, and adjacent history correction processing. The image data in the image memory 23 of the storage unit 7 is processed by each processing. Image processing is performed using the parameter 25, and final image data is obtained through a process of storing in the image memory 23 every time processing is completed. The control unit 9 sends the finally obtained image data to the printing unit 11 and performs image printing 21.

(1-2. Configuration of Storage Unit 7)
FIG. 3 shows the contents of the storage unit 7 of the thermal printer 1. The storage unit 7 includes an image memory 23 unit that stores target image data to be subjected to image processing, and a processing parameter 25 unit that stores parameters used when performing image processing. Although not described here, the storage unit 7 also records a control program, control parameters for the printing unit 11 (thermal head), and the like.

In the image memory 23, the image data 3 as the original image acquired by the thermal printer 1 is registered as an image G ₁ 27-1. The image G ₂ 27-2, the image G ₃ 27-3, the image G ₄ 27-4, the image G ₅ 27-5, the contour R ₁ 29-1, and the contour R ₂ 29-2 are image processing 19 (FIG. 2). It is registered as data calculated in the process. Note that data in the calculation process other than the original image G ₁ 27-1 and the final data image G ₅ 27-5 do not have to remain in the image memory 23.

  Further, as the processing parameter 25 of the storage unit 7, the adjacent history correction parameter 31, the contour extraction parameter 33, and the gradation conversion parameter 35, which are parameters for image processing, are recorded. Details will be described later.

(2. Processing procedure)
(2.1 Acquisition of image data 3)
FIG. 4 shows a flowchart of the image processing 19 (FIG. 2). Conventionally, as a method for correcting the heat accumulation of the thermal head of the thermal printer 1, there has been a method in which image data is read into a line memory in units of columns and is printed each time one column (or a plurality of columns) of data correction is completed. . In the present embodiment, printing is performed after data correction is performed on the entire image data to be printed. In particular, the feature of the present embodiment is that the image characteristics of the image data, for example, the contour characteristics of the image and the like are reflected in the correction.

  FIG. 4 shows a flowchart. FIG. 5 is a diagram visually showing image data corresponding to the flowchart of FIG.

  First, the image input unit 5 of the thermal printer 1 reads the image data 3 (step 1001). If the image data 3 has, for example, the number of pixels 640 × 480, each pixel has a pixel value 57 (for example, shown in FIG. 11). If the image is a single color, the image data 3 is composed of 640 × 480 data, which is the same as the number of pixels. If the image is a color image, since one pixel has pixel values for four colors of cyan, magenta, yellow, and black, the image data 3 has the number of pixels × the number of colors (for example, 640 × 480 × 4). It consists of data.

  In the present embodiment, the image data 3 is described as having a single color. When the image data 3 is a color image, image correction processing is performed on the pixel values of the respective colors.

The control unit 9 of the thermal printer 1 registers the image data 3 input from the image input unit 5 in the image memory 23 of the storage unit 7 as the acquired image G ₁ 27-1 (step 1002).

(2.2 Outline extraction process 37)
Next, the control unit 9 obtains the image _G 1 27-1 from the image memory 23, the contour extraction processing of the image _G 1 27-1 37 performs (see FIG. 5) to obtain a contour _R 1 29-1 (step 1003). The contour extraction process 37 is a process for extracting a contour portion from an image using the contour extraction parameter 33 registered in the storage unit 7.

  The contour extraction parameter 33 is a contour extraction pattern 47 (shown in FIG. 7) and includes various parameters (extraction width, table size, etc.) for creating a contour extraction pattern. FIG. 6 is a diagram for explaining the contour extraction setting 2001 for selecting or creating the contour extraction parameter 33. Although not shown in FIG. 1, it is assumed that the operator performs contour extraction setting 2001 from a setting unit connected to the bus 13 of the thermal printer 1, for example. The result of the contour extraction setting 2001 is registered as a contour extraction parameter 33 in the storage unit 7.

  In the contour extraction setting 2001, when a prescribed pattern is used (YES in step 2002), the operator selects the contour extraction pattern 47 (step 2003). When the contour extraction pattern 47 is selected, the contour extraction setting is completed (step 2006). FIGS. 7A, 7B, and 7C show contour extraction patterns 47-1, 47-2, and 47-3 for contour extraction, respectively. In either case, the pattern size is 7 × 7.

  The contour extraction pattern 47-1 in FIG. 7A has the value of the parameter 51-1 at the pixel position in the vertical direction ± 3 and the horizontal direction ± 3 with respect to the pixel of interest 49-1. The parameter 51-1 is weighted differently depending on the pixel position. The empty data 53-1 is a pixel position without weighting. That is, in the contour extraction pattern 47-1, the contour extraction calculation is performed on the pixel value of the table size 7 × 7 with the pixel of interest 49-1 as the center.

The calculation formula is represented by Formula (1), where P is the pixel value of the pixel of interest 49-1, and P ′ is the pixel value after the calculation.
P ′ = P− (P ₁ × C ₁ + P ₂ × C ₂ + P ₃ × C ₃ ... P _n × C _n ) (1)
Here, P ₁ , P ₂ , P ₃ ... P _n are pixel values around the pixel of interest 49-1, and C ₁ , C ₂ , C ₃ ... C _n are weights for the respective pixel values. The value of the parameter 51-1.

The calculation of Expression (1) is performed by sequentially setting all the pixels of the image G ₁ 27-1 to the target pixel 49-1. When the contour is extracted using the contour extraction pattern 47-1 in FIG. 7A, the outside of the contour of the processing target image is extracted. However, contours with missing corners are extracted.

Next, when the contour extraction is performed by sequentially using all the pixels of the image G ₁ 27-1 as the target pixel 49-1 using the contour extraction pattern 47-2 in FIG. 7B, the contour of the processing target image is displayed. The outside of is extracted.

Similarly, when the contour extraction is performed using the contour extraction pattern 47-3 in FIG. 7C as the pixel of interest 49-1 in order for all the pixels of the image G ₁ 27-1, the inside of the contour of the processing target image is displayed. Extracted. In the present embodiment, the contour extraction process 37 of the image G ₁ 27-1 is performed using the contour extraction pattern 47-3 in FIG. Which contour extraction pattern 47 is selected is selected according to the feature of the image. As shown in FIG. 5, since the original image G ₁ 27-1 is a white character “ABC”, the inside of the contour of the processing target image is extracted.

  The contour extraction pattern size described in FIG. 7 is 7 × 7. However, for example, when the vertical and horizontal resolutions (main scanning direction and sub-scanning direction) of the image are different, the vertical and horizontal sizes are set to different values. By selecting an extraction pattern (for example, 9 × 7), the contour extraction accuracy can be improved.

  Returning to step 2002 of FIG. 6, when the prescribed pattern is not used for the contour extraction setting 2001 (NO in step 2002), the operator creates a pattern (step 2004). The pattern creation is to create a contour extraction pattern 47 as shown in FIG. 7, and the contour extraction width, the table size (7 × 7 in FIG. 7), the target pixel position (in FIG. 7, at the center of the table). A certain [4, 4] position), a scale (table scale, etc.), an offset (shift in table position), a filter value (parameter value as weight), and the like are designated. The operator can arbitrarily set a contour extraction pattern that is optimal for contour extraction in accordance with the characteristics of the image.

  The created pattern is registered as the contour extraction parameter 33 in the storage unit 7 (step 2005), and the setting is completed (step 2006).

Returning to step 1003 in FIG. 4, the extracted data of the contour R ₁ 29-1 is registered in the image memory 23 of the storage unit 7.

Then performed and the image _G 1 27-1, by using the data of the contour _R 1 29-1, extraction processing portion of the image _G 1 27-1 except outline _R 1 29-1 39 (FIG. 5), An image G ₂ 27-2 is obtained (step 1004). When the pixel value at the pixel position [X, Y] of the contour R ₁ 29-1 is “0”, the pixel value of the image G ₁ 27-1 at the pixel position [X, Y] is extracted, and the image G ₂ 27-2 is obtained. As illustrated in FIG. 5, the image G ₂ 27-2 is an image obtained by removing the contour portion from the original image G ₁ 27-1.

(2.3 Gradation conversion processing 41)
Next, the control unit 9 performs gradation conversion processing 41 on the image G ₂ 27-2 to obtain an image G ₃ 27-3 (step 1005). The gradation conversion process 41 is to adjust the brightness of the image by multiplying all pixels by the gradation ratio using the gradation conversion parameter 35 registered in the storage unit 7.

Here, the gradation conversion setting 3001 will be described with reference to FIG. Similar to the contour extraction setting 2001 described above, the operator can set the gradation ratio. That is, the operator inputs the gradation ratio (k%) with respect to the original image G ₁ 27-1 as the gradation conversion setting 3001 from the setting unit connected to the bus 13 of the thermal printer 1 (step 3002). The setting is finished (step 3003).

The set gradation ratio (k%) is registered in the storage unit 7 as the gradation conversion parameter 35. An arithmetic expression for gradation conversion is represented by Expression (2), where P is a pixel value and P ′ is a pixel value after the calculation.
P ′ = P × k × 0.01 (2)
The gradation conversion processing 41 is performed on all the pixels of the image G ₂ 27-2, and the obtained image G ₃ 27-3 is registered in the image memory 23 of the storage unit 7.

(2.4 Adjacency History Correction Processing 43)
Then, at the same time it returns to step 1002 of FIG. 4, the control unit 9 when performing the above-described outline extraction process 37 to the image _G 1 27-1 (see FIG. 5), adjacent to the image _G 1 27-1 A history correction process 43 (see FIG. 5) is performed. The adjacent history correction process 43 performs an operation of correcting the thermal history of the thermal head for the image of interest using the adjacent history correction parameter 31 registered in the storage unit 7 to calculate a corrected image G ₄ 27-4. It is processing to do.

  Since the thermal head stores heat and the density of the printed image becomes non-uniform as the printing time elapses, the thermal printer 1 preliminarily corrects the input image to the thermal head in consideration of this heat storage history. The adjacent history correction parameter 31 is a parameter for performing this preliminary correction.

  FIG. 9 is a diagram for explaining the adjacent history correction setting 4001 for selecting or creating the adjacent history correction parameter 31. It is assumed that the operator performs an adjacent history correction setting 4001 from a setting unit connected to the bus 13 of the thermal printer 1, for example. The result of the adjacent history correction setting 4001 is registered as the adjacent history correction parameter 31 in the storage unit 7.

  When a correction file is used in the adjacent history correction setting 4001 (YES in step 4002), the operator designates and opens the file name of the adjacent history correction parameter 31 registered in the storage unit 7 (step 4003). When the adjacent history correction parameter 31 is selected, the adjacent history correction setting ends (step 4005).

  As shown in FIG. 10, the adjacent history correction parameter 31 is a weight set to the pixel values of the peripheral pixels of the target pixel 55. For example, the unit shown in FIG. 10 is “%”. This weighting is added to the pixel values of the peripheral pixels of the pixel of interest 55 and the pixel of interest 55 is corrected. In FIG. 10, the table size is 5 × 5, and the target pixel 55 is placed at the pixel position [3, 5]. Assuming that the fifth column with the pixel of interest 55 is a print row, the fourth column is a row printed immediately before, the third column is a row printed before that, and so on. Further, the third horizontal row of the target pixel 55 is an adjacent pixel to which the thermal head of the thermal printer 1 moves in parallel.

  In FIG. 10, when the target pixel 55 is 100%, the adjacent history correction parameters 31 of the peripheral pixels are Ca = −2%, Cb = −2%, Cc = −1%, Cd = −2%, Ce = −. 1% ... is set. FIG. 11 is a table showing the pixel value 57 of the image to be corrected, and corresponds to the adjacent history correction parameter 31 in FIG. P, Pa, Pb, Pc,... Are pixel values 57. For example, if the pixel value 57 is a large value, it indicates a dark color.

For example, if the total pixel value 57 in FIG. 11 is 100 (P = Pa = Pb = Pc... = 100), the calculation formula of the adjacent history correction process 43 is P as the pixel value of the target pixel 55. Assuming that the pixel value after the calculation is P ′, the equation (3) is obtained.
P ′ = P + (P _a × C _a + P _b × C _b + P _c × C _c ...) (3)

When calculated using the numerical values of FIG. 10 and FIG.
The pixel value P ′ after the calculation of the pixel of interest 55 is
P ′ = 100 + (-2-2-1-2-1-4-5-4-9-10-9) = 51
And the corrected pixel value P ′ = 51 is obtained.

  Returning to step 4002 of FIG. 9, when the correction file is not used (NO in step 4002), the operator creates a correction file, that is, the adjacent history correction parameter 31 (step 4004). The creation of the adjacent history correction parameter 31 is to create a table of the adjacent history correction parameter 31 shown in FIG. 10, and the table size (5 × 5 in FIG. 10) and the target pixel position ([3, 5 in FIG. 10). ] Position), scale (table scale, etc.), offset (shift in table position), and parameter values in the table.

  The created adjacent history correction parameter 31 is registered in the storage unit 7 and the setting is completed (step 4005).

Returning to FIG. 4, when all the pixels of the image G ₁ 27-1 are sequentially set as the target pixel 55 and the adjacent history correction is performed using the adjacent history correction parameter 31, an image G ₄ 27-4 is obtained as a corrected image. (Step 1006). The image G ₄ 27-4 is registered in the image memory 23 of the storage unit 7.

Next, using the data of the image G ₄ 27-4 and the contour R ₁ 29-1, the contour extraction processing 38 (FIG. 5) of the image G ₄ 27-4 is performed to obtain the contour R ₂ 29-2 ( Step 1007). That is, the pixel value of the image G ₄ 27-4 at the pixel position [X, Y] when the pixel value at the pixel position [X, Y] of the contour R ₁ 29-1 is not “0” is extracted. R ₂ 29-2 is obtained. According to FIG. 5, the contour R ₂ 29-2 is an image obtained by extracting the contour from the image G ₄ 27-4. The contour R ₂ 29-2 is registered in the image memory 23 of the storage unit 7.

(2.5 Composition 45)
Next, the control unit 9 takes out the image G ₃ 27-3 and the contour R ₂ 29-2 from the image memory 23 of the storage unit 7, and places the contour R ₂ 29-2 on the front surface of the image G ₃ 27-3. Then, the composition processing 45 is performed to obtain an image G ₅ 27-5 (step 1008). The image G ₅ 27-5 is registered in the image memory 23 of the storage unit 7.

The control unit 9 ends the process of the image processing 19 and sends the data of the image G ₅ 27-5 to the printing unit 11 (thermal head) (step 1009).

The printing unit 11 controls the applied energy of the thermal head according to the data of the image G ₅ 27-5, and prints out the image (step 1010).

  In the present embodiment, the processing is performed at a time according to the procedure shown in the image processing 19 of FIG. 4, but the contour extraction processing 37, the gradation conversion processing 41, the adjacent history correction processing 43, and the like are performed for each processing. May be performed while confirming the setting.

  Further, the process is not limited to the procedure of the image processing 19 described in FIG. 4, and the process may be performed by another procedure in order to perform the optimum heat storage correction process.

  In the present embodiment, the thermal printer 1 in FIG. 1 has been described as having the control unit 9, but a control unit (computer or the like) that performs image processing may be provided separately from the thermal printer 1. In this case, image processing (heat storage correction processing) of the image data is performed by an external control unit, and the image-processed data is input to the thermal printer 1 for printing.

  In the present embodiment, the image data 3 is described as having a single color. However, when the image data is in color, one pixel has respective pixel values of cyan, magenta, yellow, and black. The image processing of the present embodiment is performed on the pixel values of the image data, and the heat accumulation correction processing of the image data printed by the thermal printer 1 is performed.

  The present embodiment can also be used as a heat storage correction method in a thermal recording type thermal printer in which a thermal recording sheet is heated directly by a thermal head to directly develop a color.

(3. Effects, etc.)
As described above, according to the present embodiment, since the heat storage correction processing is performed in consideration of the difference in the areas other than the contour portion and the contour portion, optimum correction is performed for both the contour portion and the non-contour portion. The Therefore, there is an effect of eliminating problems such as generation of wrinkles due to excessive or insufficient heat storage correction amount, damage to the ink ribbon, and blurring of the contour portion.

  In addition, according to the present embodiment, since the optimum heat accumulation correction process according to the image characteristics can be performed, there is an effect of improving the image quality of the thermal printer output image.

  The technical scope of the present invention is not limited to the embodiment described above. It will be apparent to those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea disclosed in the present application, and these are naturally within the technical scope of the present invention. Understood.

The figure which shows the structure of the thermal printer 1 in this Embodiment. Diagram showing heat storage correction device and method The figure which shows the structure of the memory | storage part 7 Flow chart of heat storage correction method image data Outline extraction setting procedure Outline extraction pattern 47 Tone conversion setting procedure Neighboring history correction setting procedure Adjacent history correction parameter 31 Pixel value 57

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ......... Thermal printer 3 ......... Image data 5 ......... Image input part 7 ......... Storage part 9 ......... Control part 11 ......... Print part 13 ......... Bus 15 ......... Output image 17 ... ...... Image reading 19 ......... Image processing 21 ......... Image printing 23 ......... Image memory 25 ......... Processing parameters 27-1 to 27-5 ......... Image data 29-1, 29-2 ......... Contour data 31 ......... Adjacent history correction parameter 33 ......... Contour extraction parameter 35 ......... Tone conversion parameter 37, 38 ......... Contour extraction processing 39 ......... Extraction processing other than contour 41 ......... Floor Tone conversion processing 43... Adjacent history correction processing 45... Composition processing 47-1 to 47-3 ... Contour extraction patterns 49-1 to 49-3, 55. 3 ... Parameters 53-1 to 53- ......... sky data 57 ......... pixel values

Claims (6)

In a thermal recording apparatus having a thermal head, a thermal storage correction apparatus that performs thermal storage correction by image data processing to original image data of a screen to be printed,
  First contour extraction means for extracting a contour portion of the original image data;
  Gradation converting means for adjusting the brightness of the original image data other than the contour portion extracted by the first contour extracting means;
  Adjacent history correction means for performing thermal history correction considering the surrounding pixel data of each pixel for the original image data,
  A second contour extracting means for extracting a contour portion of the image data whose thermal history is corrected by the adjacent history correcting means, using the contour portion extracted by the first contour extracting means;
  Image synthesis means for synthesizing image data other than the outline portion adjusted in brightness by the gradation converting means, and an outline portion in which the thermal history extracted by the second outline extraction means is corrected;
A heat storage correction device characterized by comprising: The heat storage correction device according to claim 1, wherein the first contour extraction means performs processing using a predetermined contour extraction pattern. The heat storage correction apparatus according to claim 2, wherein the predetermined contour extraction pattern is set to an optimum contour extraction pattern for contour extraction in accordance with characteristics of the original image. The heat storage correction device according to any one of claims 1 to 3, wherein the adjacent history correction unit performs processing according to a predetermined adjacent history correction parameter. In a thermal recording apparatus having a thermal head, a thermal storage correction method for performing thermal storage correction by image data processing to original image data of a screen to be printed,
A first contour extraction step of extracting a contour portion of the original image data;
  A gradation conversion step of adjusting the brightness of the original image data other than the contour portion extracted by the first contour extraction step;
  For the original image data, an adjacent history correction step for performing thermal history correction considering peripheral pixel data of each pixel,
  A second contour extraction step of extracting a contour portion of the image data in which the thermal history is corrected by the adjacent history correction step, using the contour portion extracted by the first contour extraction step;
  An image synthesis step for synthesizing image data other than the contour portion whose brightness has been adjusted by the gradation conversion step, and a contour portion in which the thermal history extracted by the second contour extraction step is corrected,
A heat storage correction method characterized by comprising: A thermal recording apparatus having a thermal head,
  Image input means for acquiring and recording original image data of a screen to be printed;
  First contour extraction means for extracting a contour portion of the original image data;
  Gradation converting means for adjusting the brightness of the original image data other than the contour portion extracted by the first contour extracting means;
  Adjacent history correction means for performing thermal history correction considering the surrounding pixel data of each pixel for the original image data,
  A second contour extracting means for extracting a contour portion of the image data whose thermal history is corrected by the adjacent history correcting means, using the contour portion extracted by the first contour extracting means;
  Image synthesis means for synthesizing image data other than the outline portion adjusted in brightness by the gradation converting means, and an outline portion in which the thermal history extracted by the second outline extraction means is corrected;
Printing means for sending and printing image data obtained by the image synthesis means to the thermal head;
A thermal recording apparatus comprising:

Images