JPH09323438A - Method and device for thermal recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably record a thermally sensitive image with high quality by a method wherein a predetermined image processing is applied to image data supplied from an image data supply source and a thermal head is driven in accordance with the processed image data. SOLUTION: Image data from an image data supply source R is transmitted to an image processing section 80. The image processing section 80 receives the image data from the image data supply source R and applies predetermined image processing to the image data. It further applies formatting to the image data at need to convert it to thermal recording image data corresponding to the thermal recording by means of a thermal head 66. In correction processes, a sharpness correction process, a gradation correction process, a shading correction process, a resistance value correction process and a temperature rising correction process are sequentially executed and an image data representative value calculation process for correction of temperature rising is executed in front of or after one of the processes after the gradation correction process. A black ratio correction process and/or a load variation correction process is preferably applied among the shading correction, resistance value correction process and temperature rising correction process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal recording method and apparatus using a thermal head.

[0002]

2. Description of the Related Art An image recording using a heat-sensitive recording material (hereinafter, referred to as a heat-sensitive material) in which a heat-sensitive recording layer is formed using a film or the like as a support for recording an ultrasonic diagnostic image (hereinafter referred to as a heat-sensitive image recording). Is used. In addition, thermal image recording has advantages such as no necessity of wet development processing and easy handling. In recent years, not only small-sized image recording such as ultrasonic diagnosis but also CT diagnosis,
For applications requiring large and high-quality images, such as RI diagnosis and X-ray diagnosis, use for image recording for medical diagnosis is also being studied.

[0003] As is well known, thermal image recording uses a thermal head having a glaze in which heating elements are arranged in one direction, in which a thermal recording layer of a thermal material is heated to record an image. While slightly pressing the (thermosensitive recording layer), both are relatively moved in a direction perpendicular to the glaze extending direction, energy is applied to each heating element of the glaze, and heating is performed according to a recorded image. Thereby, the image recording is performed by heating the heat-sensitive recording layer of the heat-sensitive material.

[0004]

In such a thermal recording apparatus, image data is received from an image data supply source such as a CT diagnostic apparatus or an MRI diagnostic apparatus, and an image processing apparatus performs sharpness correction or correction on the image data. By performing predetermined image processing (correction) such as gradation correction to obtain heat-sensitive recording image data according to heat-sensitive recording, the thermal head is driven according to the heat-sensitive recording image data to generate heat in each heat-generating element, thereby generating an image. A thermal image corresponding to the image data supplied from the data supply source is recorded.

Here, as the image processing performed by the image processing apparatus of the thermal recording apparatus, specifically, sharpness correction (sharpness processing) for enhancing the contour of the image; Gradation correction for obtaining an appropriate image corresponding to individual differences of recording devices; temperature rise correction that adjusts heat generation energy according to the temperature of the heating element; correction of density unevenness caused by shape variation of glaze of thermal head Shading correction; resistance value correction for correcting the difference in resistance value of each heating element; for developing image data corresponding to the same density with the same density regardless of the change in the thermal head power supply voltage drop amount due to the change in the recording pattern. Black ratio correction; Load fluctuation correction for correcting streak-like density unevenness caused by a change in frictional force between the heat-sensitive material and the thermal head depending on recording density; And so on.

In the image recording device, the image data is usually supplied as numerical data, and also in the thermal recording device, the image data is supplied as numerical data, for example, 10-bit digital data from the image data supply source. Image data is multiplied by correction factors and averaged,
Various types of image processing are being performed. However, when performing a combination of a plurality of image processes performed by directly changing the image data in this way, it is not possible to perform appropriate image processes depending on the order in which the processes are performed, and the expected correction effect is obtained. In some cases, an image with a desired image quality cannot be obtained, that is, the image quality of a recorded image may deteriorate.

[0007] The deterioration of the image quality of the recorded image becomes a serious problem in the application where high quality image recording is required.
In particular, in applications such as the above-mentioned medical applications where high-quality images are required, it becomes an obstacle to image observation and becomes a serious problem leading to a mistake in diagnosis.

An object of the present invention is to solve the above-mentioned problems of the prior art, and in a thermal recording apparatus using a thermal head, an expected correction effect can be sufficiently obtained in all image processing (correction) performed. A heat-sensitive recording method capable of stably recording a high-quality heat-sensitive image with heat-sensitive recording image data that has been appropriately image-processed, and a heat-sensitive recording apparatus using this heat-sensitive recording method. To provide.

[0009]

In order to achieve the above-mentioned object, the present invention applies a predetermined image processing to image data supplied from an image data supply source, and in accordance with the processed image data, a thermal head. A thermal recording method in which thermal recording is performed by driving, wherein the image processing first performs sharpness correction and gradation correction, then shading correction and resistance value correction, and finally temperature rise correction, and A thermal recording method is provided, which is performed before or after any processing after gradation correction or in a predetermined order of performing a representative value calculation processing of image data for the temperature rise correction.

Here, after the shading correction and the resistance value correction and before the temperature rise correction, it is preferable to further perform the black ratio correction and / or the load variation correction.
Further, it is preferable to perform the gradation correction after the sharpness correction, or it is preferable to perform the sharpness correction after the gradation correction, and further, after that, the obtained sharpness is obtained. Of the print data after the correction processing, all print data having a value smaller than a value kE ₀ obtained by multiplying the print data value E ₀ corresponding to the image data value 0 by a constant k (k <1) is kE.
More preferably, it is converted to ₀ .

In the shading correction and the resistance value correction, the correction having the higher image density dependency is performed first. If the image density dependency of both corrections is equivalent, an arbitrary order or shading correction and resistance value correction are performed. It is preferable to perform the correction at the same time. Further, it is preferable that the black ratio correction is performed before the load variation correction.

Further, according to the present invention, a thermal head having a glaze formed by arranging heating elements in one direction is brought into contact with the thermal recording material, and the thermal head is heated in a direction orthogonal to the arrangement direction of the heating elements. The means for moving the head and the thermal recording material relatively, and the image data supplied from the image data supply source are first subjected to sharpness correction and gradation correction, and then subjected to shading correction and resistance value correction, and finally. Is subjected to temperature rise correction, and before or after any processing after gradation correction, image processing means for performing representative value calculation processing of image data for the temperature rise correction, and the image processing means. And a recording control unit for driving the thermal head based on the image data.

Here, it is preferable that the image processing means further performs black ratio correction and / or load variation correction after the shading correction and the resistance value correction and before the temperature rise correction. Further, it is preferable that the image processing means performs the gradation correction after the sharpness correction, or it is preferable that the sharpness correction be performed after the gradation correction. A value k obtained by multiplying the recording data value E ₀ corresponding to the image data value 0 by a constant k (k <1) among the recording data after the sharpness correction process.
More preferably, all the print data having a value smaller than E ₀ is converted into kE ₀ .

Further, the image processing means first performs one of the shading correction and the resistance value correction, whichever has a higher image density dependency. It is preferable that the order or the shading correction and the resistance value correction are simultaneously performed.
Further, it is preferable that the image processing means performs the black ratio correction before the load variation correction.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The heat-sensitive recording method of the present invention and the heat-sensitive recording apparatus of the present invention using the same will now be described in detail with reference to the preferred embodiments shown in the accompanying drawings.

FIG. 1 shows a schematic view of an example of the thermal recording apparatus of the present invention utilizing the thermal recording method of the present invention. FIG.
Is a thermosensitive recording device 10 (hereinafter, referred to as a recording device 10) that performs thermal image recording on a thermosensitive recording material (hereinafter, referred to as a thermosensitive material A) which is a cut sheet of a predetermined size such as a B4 size. The loading unit 14 into which the magazine 24 containing the heat-sensitive material A is loaded,
6. It has a recording unit 20 for recording a thermal image on the thermal material A by the thermal head 66, and a discharge unit 22. As shown in FIG. 2, an image processing unit 80 and a recording control unit 84 are connected to the thermal head 66 of the recording unit 20, and a data storage unit 86 is connected to the image processing unit 80.

In such a recording apparatus 10, the supply / conveyance unit 16 conveys the thermosensitive material A to the recording unit 20 and presses the thermal head 66 against the thermosensitive material A, while extending the glaze (see FIGS. 1 and 2). The heat-sensitive material A is conveyed in a direction orthogonal to the paper surface (in FIG. 2) and each heating element is heated in accordance with the recorded image, thereby recording the heat-sensitive image on the heat-sensitive material A.

The heat-sensitive material A comprises a film such as a transparent polyethylene terephthalate (PET) film or paper as a support, and a heat-sensitive recording layer formed on one surface thereof. Such a heat-sensitive material A is usually formed into a laminated body (bundle) of a predetermined unit such as 100 sheets and packaged in a bag body or a band. In the illustrated example, the heat-sensitive recording layer is kept in a predetermined unit bundle. Is placed in the magazine 24 of the recording apparatus 10 with the lower side as the lower surface, and the sheets are taken out from the magazine 24 one by one and used for thermal image recording.

The magazine 24 is a housing having a lid 26 that can be opened and closed. The magazine 24 stores the heat-sensitive material A and is loaded in the loading section 14 of the recording apparatus 10. The loading unit 14 includes the recording device 10
Insertion hole 30 formed in housing 28 of
And the guide rolls 34, 34, and the stop member 36, and the magazine 24 is inserted into the insertion port 30 with the lid 26 side first.
Is inserted into the recording device 10, is guided by the guide plate 32 and the guide roll 34, and is pushed to a position where it abuts on the stop member 36, so that the recording device 10 is loaded at a predetermined position.

The supply / conveyance means 16 takes out the thermosensitive material A from the magazine 24 loaded in the loading section 14 and conveys it to the recording section 20, and uses a sucker 40 for adsorbing the thermosensitive material A by suction. It has a mechanism, a conveyance means 42, a conveyance guide 44, and a regulation roller pair 52 located at the exit of the conveyance guide 44. The conveying means 42 includes a conveying roller 46, a pulley 47a coaxial with the conveying roller 46,
It has a pulley 47b and a tension pulley 47c connected to a rotary drive source, an endless belt 48 stretched over these three pulleys, and a nip roller 50 pressed by a transport roller 46. The heat-sensitive material A is conveyed by holding the tip of the leafed heat-sensitive material A between the conveyance roller 46 and the nip roller 50.

When a recording start instruction is issued in the recording apparatus 10, the lid 26 is opened by an opening / closing mechanism (not shown), and the sheet-fed mechanism using the suction cup 40 takes out one sheet of the heat-sensitive material A from the magazine 24, and the heat-sensitive material is discharged. The leading end of A is supplied to the conveying means 42 (conveying roller 46 and nip roller 50). When the heat-sensitive material A is nipped by the conveyance roller 46 and the nip roller 50, the suction by the suction cup 40 is released, and the supplied heat-sensitive material A is guided by the conveyance guide 44 and regulated by the conveyance means 42 to the regulating roller pair 52.
Transported to When the heat-sensitive material A to be recorded is completely discharged from the magazine 24, the lid 26 is closed by the opening / closing means.

The distance from the conveying means 42 defined by the conveying guide 44 to the regulating roller pair 52 is set to be slightly shorter than the length of the heat-sensitive material A in the conveying direction.
The leading end of the heat-sensitive material A reaches the regulating roller pair 52 by the conveyance by the conveying means 42, but the regulating roller pair 52 is initially stopped, and the leading end of the heat-sensitive material A is temporarily stopped and positioned here. At the time when the tip of the heat-sensitive material A reaches the regulating roller pair 52, the temperature of the thermal head 66 (glaze 66a) is confirmed. Is started, and the heat-sensitive material A is conveyed to the recording unit 20.

FIG. 2 shows a schematic diagram of the recording unit 20. The recording unit 20 includes a thermal head 66, a platen roller 60,
The cleaning roller pair 56, the guide 58, a cooling fan 76 (see FIG. 1) for cooling the thermal head 66 and the guide 62, and the image processing unit 8 constituting a recording control system
0 and a recording control unit 84. Thermal head 66
Is, for example, capable of recording images up to a maximum of B4 size.
A thermal image recording apparatus capable of performing thermal image recording at a recording (pixel) density of about 300 dpi, in which heating elements for performing thermal recording on the thermal material A are arranged in one direction (perpendicular to the paper surface in FIGS. 1 and 2). It has a thermal head main body 66b on which the thermal head 66a is formed, and a heat sink 66c fixed to the thermal head main body 66b. The thermal head 66 is supported by a support member 68 that is rotatable about a fulcrum 68a in the direction of arrow a and in the opposite direction.

The platen roller 60 holds the heat-sensitive material A at a predetermined position, rotates at a predetermined image recording speed, and conveys the heat-sensitive material A in a direction orthogonal to the main scanning direction (direction of arrow b in FIG. 2). . The cleaning roller pair 56 is a roller pair including an adhesive rubber roller 56a, which is an elastic body, and a normal roller 56b. The adhesive rubber roller 56a removes dust and the like adhering to the heat-sensitive recording layer of the heat-sensitive material A, and glazes 66a. This prevents dust from adhering to the surface and adversely affecting image recording.

In the recording apparatus 10 of the illustrated example, before the heat-sensitive material A is conveyed, the support member 68 is rotated upward (in the direction opposite to the arrow a direction) and the thermal head 66 (glaze 66a). It is not in contact with the platen roller 60. When the transportation by the regulation roller pair 52 is started, the heat-sensitive material A is then nipped by the cleaning roller pair 56 and further transported while being guided by the guide 58. When the leading end of the heat-sensitive material A is transported to the recording start position (the position corresponding to the glaze 66a), the support member 68
Rotates in the direction of the arrow a, the heat sensitive material A is sandwiched between the glaze 66a of the thermal head 66 and the platen roller 60, and the glaze 66a is pressed against the recording layer, and the heat sensitive material A is moved by the platen roller 60. While being held at a predetermined position, the platen roller 60 (and the regulation roller pair 52 and the conveyance roller pair 63) conveys it in the direction of arrow b. With this conveyance, each heating element of the glaze 66a is heated according to the recorded image, so that the heat-sensitive material A
The thermal image recording is performed.

As described above, the recording control system of the thermal head 66 basically comprises the image processing section 80 and the recording control section 84. The image processing unit 80 is connected to a data storage unit 86 that stores data for various types of image processing (correction) performed by the image processing unit 80 and image data supplied from the image data supply source R. Is done. Further, the portion corresponding to the glaze of the base 66d of the heat sink 66c of the illustrated thermal head 66 includes:
Thermistors are arranged at predetermined intervals, for example, at five places, detect the temperature of the glaze 66a (that is, the temperature of the heating element in this portion), and, as indicated by the two-dot chain line, convert the detection result into an image processing unit. Send to 80. The image processing unit 80 receives the detection result, and detects the temperature of each heating element by, for example, linear interpolation. A thermometer T for detecting an ambient temperature near the thermal head 66 is provided in the recording unit 20, and sends a measurement result to the image processing unit 80.

The image data from the image data supply source R such as CT or MRI is sent to the image processing section 80 as, for example, 10-bit (0-1023) digital data. The image processing unit 80 is configured by combining various image processing circuits and memories, receives image data from the image data supply source R, performs predetermined image processing (correction) on the image data, and further, Perform the format (enlargement / reduction, frame assignment) as necessary and use the thermal head 66.
The image data is heat-sensitive recording image data according to the heat-sensitive recording by.

In the heat-sensitive recording apparatus according to the present invention, these correction processes are performed in the order of sharpness correction and gradation correction (density correction) → shading correction and resistance value correction → temperature rise correction. Image data representative value calculation processing for temperature rise correction (for example, thinning processing is a typical example) is performed in a predetermined order before or after any image processing after the tone correction, but shading is performed. It is preferable to perform the black ratio correction and / or the load variation correction between the correction and the resistance value correction and the temperature rise correction. For example, in the recording apparatus 10 of the illustrated example, sharpness correction → gradation correction → image data representative value calculation processing for temperature rise correction → shading correction / resistance value correction (simultaneous) → black ratio correction → load fluctuation correction → Image processing may be performed in the order of temperature rise correction, or gradation correction → sharpness correction (including false contour reduction processing) → shading correction → image data representative value calculation processing for temperature rise correction → resistance The image processing may be performed in the order of value correction → black ratio correction → load variation correction → temperature rise correction, but it is preferable that the image processing is performed in the latter order in the apparatus of the illustrated example.

As described above, according to the present invention, the order of gradation correction and sharpness correction, the order of shading correction and resistance value correction, whether or not to perform black ratio correction and load variation correction, and when The order and the time (order) for performing the image data representative value calculation process for the temperature rise correction depend on the type and size of the heat sensitive material A, the recording device 10, the image quality required for the reproduced image, and a combination thereof. It can be appropriately selected. Hereinafter, each correction process performed in the method of the present invention will be described.

The sharpness correction (sharpness processing) is a correction for enhancing the sharpness of the image by emphasizing the contour of the recorded image in order to obtain a clear and sharp image. Various known methods can be used for the sharpness correction. For example, the sharpness correction is performed as follows. One screen is divided into n × n pixels, and a certain pixel line i
Let S _ij (i = 1, 2 ... n, j = 1, 2 ... n) be j-th image data in the extending direction of the glaze 66a in
In the sharpness correction, this image data S _ij is first
It is converted into a ^first unsharpness signal U ¹ _ij which is electrically blurred image data. The first unsharpness signal U ¹ _ij is obtained by averaging the image data S _ij and the image data around it.

[Equation 1] Is required. Note that M is the first unsharpness signal U
It is the number of pixels used to create ¹ _ij , that is, the mask size, and L is defined by (M-1) / 2.

Then, the first unsharpness signal U ¹ _ij
Are further averaged to obtain a second unsharpness signal U ² _ij
Is calculated. The second unsharpness signal U ² _ij is
Like the unsharpness signal U ¹ _ij , it is calculated by the following equation (2).

[Equation 2]

Then, the first unsharpness signal U ¹ _ij
And the second unsharpness signal U ² _ij . Then, the difference is multiplied by the sharpness correction coefficient K and the first unsharpness signal U ¹ _ij is added, that is, the sharpness-corrected image data S _ij is obtained by the following formula (3). . S _ij = U ¹ _ij + K · (U ¹ _ij −U ² _ij ) (3)

Here, the sharpness of the thermal recording image is influenced by the temperature of the thermal head 66 (heating element), the recording speed, the γ value of the thermal material A, etc., and the higher the temperature of the thermal head 66, the higher the recording speed. Since the sharpness of the recorded image decreases as the γ value of the heat-sensitive material A decreases as sooner as possible, the sharpness correction coefficient K may be changed accordingly to perform the sharpness correction. . In this case, for example, a table (or function) of a weighting coefficient corresponding to the temperature of the heating element, the recording speed, the γ value of the heat-sensitive material, or the like is created and read out at the time of the sharpness correction to perform the sharpness correction. A method of multiplying the coefficient K is exemplified.

Gradation correction (also referred to as density correction) corrects image data according to the state of the recording apparatus, the γ value of the heat-sensitive material A, etc., and obtains an image in which gradation (density) is properly expressed. This is a correction for As described above, the recording device 10 receives the image data as 10-bit digital data,
An image recording apparatus is provided in response to this, for example, in the case where 512 image data of digital data corresponds to a density (D) of 1.2 in this apparatus, when 512 image data is received, Basically, it is required to output an image with a density of 1.2. However, there are individual differences in the devices, and the installation environment etc. also differ. Furthermore, the γ value of the heat-sensitive material A also differs depending on the manufacturer, manufacturing lot, and the like. Therefore, it is impossible for all devices to output an image of a predetermined density according to the supplied image data. Therefore,
Gradation correction is performed to form a thermosensitive recording image in which gradation is appropriately expressed according to image data. Further, in a normal thermal recording apparatus including the recording apparatus 10 of the illustrated example, the image data sent from the image data supply source R is converted into image data according to the heat generation amount of the thermal recording by this gradation correction. It

The gradation correction method is not particularly limited, and various known methods can be used. For example, the recording device 10
To create a correction chart in which images of a plurality of densities are recorded, and measure the densities of the images recorded in the correction charts with a densitometer.
An example is a method of creating a correction table, that is, a gradation curve (or correction function) from the image density recorded in the correction chart using a density correction algorithm, and converting the image data using this correction table.

Further, the image data converted by gradation correction so as to correspond to the heat generation amount has a recording energy such that the heat-sensitive material A does not develop color (preferably immediately before color development) even if the recording density is 0. Is preferably supplied to the thermal head 66, and it is preferable to prepare the correction table in such a manner. With this configuration, the temperature difference between the heating elements during recording can be reduced,
The temperature distribution of the entire thermal head 66 can be reduced, a high quality image can be obtained, and when the base of the heat sensitive material A is a transparent PET film or the like, the surface of the heat sensitive material A is slightly melted. As a result, diffuse reflection of light can be reduced, and the transparency of the heat-sensitive material A can be improved.

The shading correction is to correct the density unevenness caused by the shape variation of the glaze 66a of the thermal head 66. As described above, the thermal head 66 has the glaze in which the heating elements are arranged in one direction, but it is difficult to make the shape of the glaze 66a uniform over all the pixels, and normally, the individual pixels are There is some variation in shape. The amount of heat generated by each heating element also differs depending on the position in the extending direction of the glaze 66a. Therefore, even if image recording is performed using image data having the same recording density, density unevenness due to this shape variation and position, so-called shading occurs. In order to correct the density unevenness, it is necessary to perform shading correction.

The shading correction method is not particularly limited, and heat energy corresponding to image data of a predetermined density is supplied to all pixels (heat generating elements) of the thermal head 66 to actually form a thermal recording image, The image density is optically measured using a densitometer, etc. so that the density of the recorded image to be formed becomes uniform from the recorded density corresponding to the image data and the density of the actually measured recorded image. An example is a method in which shading correction data (correction coefficient) for correcting image data is calculated for each pixel and stored in the data storage unit 86, and the image data is multiplied by the shading correction data. Further, the same heat energy is supplied to all the pixels of the thermal head 66 to measure the heat generation amount of each pixel,
A method of calculating similar shading correction data from the heat generation amount of each pixel and performing the correction is also exemplified. Further, if necessary, image data (image density), the thermal head 6
A correction coefficient (correction table) of shading correction data is created in accordance with the temperature of 6, the recording speed, the temperature and humidity of the heat-sensitive material A, γ, etc., and the shading correction data is corrected according to these, and shading correction is performed. You may go.

The resistance value correction is a correction for obtaining a proper image by correcting the difference in the resistance value of each heating element. The resistance values of the heating elements used in the thermal head 66 are not uniform, and the resistance values vary due to manufacturing errors and material variations. Also, the resistance value of the heating element, which is a resistor, changes depending on the use, that is, the heating time and the heating energy (heating history), but the heating history of each heating element is not uniform, and changes in the resistance value change over time. Occurs,
Variations in resistance value fluctuate. Due to such a variation in resistance value, the heat generation amount of each heat generating element is different even if heat is generated for the same time, which is one of the causes of uneven density of a recorded image. Therefore, it is necessary to correct the density unevenness resulting from this, that is, the resistance value correction.

The resistance value correction method is not particularly limited, and the resistance value of each heating element is actually measured, and resistance value correction data (for example, [R / Rm], where R is the For example, a method of calculating the resistance value of the heating element, Rm being the maximum resistance value of all the heating elements, storing it in the data storage unit 86, and multiplying it by the image data is exemplified. Also,
The resistance value of the heating element is the thermal head 66 (heating element).
Since it is also affected by the temperature and image data (image density) of the heating element, a table (function) of resistance coefficient correction data corresponding to these is created and stored in advance, and the temperature of the heating element and the image data are stored in the table. Accordingly, the correction coefficient may be read out and the resistance correction data may be multiplied by the correction coefficient to perform the resistance correction.

The black ratio correction is a correction for developing the same image data with the same density regardless of the change in the thermal head power supply voltage drop amount due to the change in the recording pattern. For example, when there are many high density areas in one line of image data, the number of heating elements that are simultaneously energized increases and the amount of current increases. For example, due to internal resistance of a power cable from a power source to a thermal head, A voltage drop occurs according to the amount of current. Therefore, the power supply voltage supplied to the thermal head fluctuates for each line and each heating element according to the density of the image data, and even if the image data is the same, a density difference occurs in the recorded image. The so-called black ratio unevenness occurs. Therefore, it is necessary to correct the density unevenness caused by this, that is, the black ratio correction.

The black ratio correction method is not particularly limited, and various known methods can be used. For example, the image data of each pixel is added for each line to calculate the total applied energy of one line. , A method of correcting the image data of each pixel based on the total applied energy, that is, assuming that the amount of voltage drop in one line is constant, the loss of thermal energy due to the voltage drop of the image data of each pixel is corrected. An example of the black ratio correction method is as follows.

Further, as a more preferable method, a method of correcting the black ratio using the following equation (a) is exemplified. In the above-described black ratio correction method, the same correction is performed based on the total energy in one line, so that low-density pixels are overcorrected. The black ratio of pixel image data can be optimally corrected.

(Equation 3) In the above formula (a), N is the number of pixels in one line, D is image data, M is the maximum value of image data, k is a correction coefficient, and D is
(N) shows the image data before correction of the pixel n, H (D) shows the correction data value for the image data D, and D _C (n) shows the image data after correction of the pixel n.

In the equation (a), first, the correction data value H (D) for each image data D is calculated. For example,
In a device in which the range of the image data D is 2048 gradations from 0 to 2047, the corresponding correction data value H
2048 correction data values from (0) to H (2047) are calculated.

At this time, when the uncorrected image data D (n) is equal to or larger than the image data D, D ′ (n) is set as the image data D, and conversely, the image data D (n) is changed to the image data D.
Is smaller than the image data D ′ (n), the image data D
(N). Then, the corrected image data D _C (n) is calculated by using the corrected data value H (D (n)) of the uncorrected image data D (n) of each pixel n.

Further, if the equation (a) is calculated as it is, the amount of calculation becomes very large, but the amount of calculation can be greatly reduced by performing the following calculation.
As shown in the following equation (b), C (D)

(Equation 4) Is written, H (D) is H (D) = 1-C (D) / (N
XM).

Here, C (D) in the case of D = M, that is, C (M) is given by the following equation (b).

(Equation 5) Is required. Since C (M−1) is calculated as M → M−1, if the number of pixels of the image data M is written as hst (M), then C (M−1) = C (M) −hst (M) Can be represented. C (M-2) is M-1, M → M
Since it is calculated as -2, C (M-2) = C (M) -hst (M-1) -2 * hst (M) = C (M-1) -hst (M-1) -hst (M ) In general,

(Equation 6) Becomes

Therefore, the calculation procedure is as follows: Step 1 The value Stotal obtained by adding the data values of all the pixels on one line, and the histogram hst of each image data included in one line.
(0), hst (1), ..., Hst (M) are calculated. Step 2 Obtain the correction value corresponding to each image data as follows. S (M) = 0 C (M) = Stotal S (M-1) = S (M) + hst (M) C (M-1) = C (M) -S (M-1) S (M- 2) = S (M-1) + hst (M-1) C (M-2) = C (M-1) -S (M-2) ... S (1) = S (2) + hst (2 ) C (1) = C (2) -S (1) -Step 3 Each pixel on one line is corrected as follows. (K is a correction _{coefficient) D C (n) = D} (n) × {1-k × (1-C (D
(N)) / (N × M))} This black ratio correction method is described in Japanese Patent Application No. 8-2 of the present applicant.
5036.

By the way, in the heat-sensitive recording apparatus 10, the frictional force at the interface between the heat-sensitive material A and the thermal head 66 changes according to the density recorded on the heat-sensitive material. Therefore, at the boundary line portion where the low-density recording portion changes to the high-density recording portion, the transport speed of the heat-sensitive material is momentarily increased, and the recording density at the boundary portion portion is reduced, resulting in white stripes. Uneven density occurs, and conversely, there is a problem that black stripe-shaped density unevenness occurs at the boundary part that changes from a high-density recording area to a low-density recording area. .

The load fluctuation correction is a correction process for preventing the occurrence of the above-mentioned streaky density unevenness, and is, for example, the image data, which is calculated in advance, between the heat-sensitive material and the thermal head. Based on the function expressing the relationship between the frictional force (conveyance torque), as shown in the following calculation formula,
By subtracting the sum of the frictional forces corresponding to each pixel on the current line from the sum of the frictional forces corresponding to each pixel on the previous line, the amount of change in the frictional force from the previous line to the current line is calculated. The image data is corrected for each pixel on each line based on the change amount of.

[0051]

(Equation 7) Here, n is the line number of the recorded image, i is the pixel number of the n-th line, and D ′ _n (i) and D _n (i) are the images of the i-th pixel of the n-th line after correction and before correction, respectively. A data value, k is a correction coefficient, H _n is an amount indicating a change in frictional force between the _n- th line thermosensitive material and the thermal head, M is the total number of pixels in one line, and f (D) is an image data value D. It is a functional expression showing the relationship between the frictional force between the heat-sensitive material and the thermal head.

By approximating the relationship between the image data and the frictional force between the heat sensitive material and the thermal head by a linear function, the image data values of the previous line and the current line are simply accumulated. It is not necessary to prepare the above function and the processing speed can be improved because the load variation correction can be performed only by adding and performing the difference between the cumulative addition value of the previous line and the cumulative addition value of the current line. There is an advantage that you can.

Further, for example, a function representing the relationship between the image data and the frictional force between the heat-sensitive material and the thermal head, which has been calculated in advance, and the frictional force between the heat-sensitive material and the thermal head, The amount of change in the amount of deformation of the rubber roller at each pixel position on each line is calculated based on the function that represents the relationship between the amount of deformation of the rubber roller, and the amount of change in the amount of deformation of the rubber roller at each pixel position on the current line. And the correction coefficient of the previous line, or instead of the change amount of the deformation amount of the rubber roller for each pixel position of the current line, the average value of the change amount of the deformation amount of the rubber roller for each line and each line It is also possible to correct the image data of the current line more accurately by using the sum of the average value of the amount of change in the deformation amount of the rubber roller of m pixels before and after each pixel position of . This load fluctuation correction method is described in detail in Japanese Patent Application No. 9-50295 filed by the present applicant.

The temperature rise correction is to adjust the heat generation energy according to the temperature of the heat generating element to correct the uneven density caused by the difference in the temperature history of each heat generating element. Each heating element of the thermal head 66 is heated, for example, by energizing for a predetermined time corresponding to the image data of each pixel of the recorded image. However, the temperature of each heating element is
Since it varies depending on the recorded image up to the previous line (heating history), even if each heating element is energized for the same time according to the same image data, a temperature difference occurs between the heating elements after heating,
Density unevenness occurs. Therefore, it is necessary to perform the temperature rise correction of the image data, which corrects the amount of heat generation based on the image data, the history of heat generation up to the previous line, and the like for each heating element.

The method of temperature rise correction is not particularly limited,
Although various known methods can be used, as an example, first, as a pre-processing, a recorded image of one screen is divided into a predetermined number of areas (blocks) having a predetermined number of pixels, and each divided area is divided. The representative value of the image data is calculated in advance, and then the predicted temperature value of each region is calculated from the representative value of the image data and the initial temperature value detected by the thermistor,
A temperature correction value for each area is calculated from this predicted temperature value, the temperature correction value for each area is interpolated to calculate the temperature correction value for each pixel of the recorded image of one screen, and this temperature correction value is used for each A method of correcting image data of pixels is exemplified.

More specifically, first, a recorded image of one screen is divided into a predetermined number of areas having a predetermined number of pixels, for example,
When the recorded image of one screen is 3072 horizontal pixels × 4224 vertical pixels, the recorded image of one screen is divided into 25 horizontal areas × 133 vertical mesh areas by the area having 128 horizontal pixels × 32 vertical pixels. To do. Then a predetermined one in the area
Method of using image data of pixels as a representative value; Method of using average value of image data of a predetermined number of remaining pixels after thinning pixels in a region as a representative value (thinning-out process); Image of all pixels in a region A method of using the average value of the data as the representative value; and the like to calculate the representative value of the image data of each divided region. Pre-processing of temperature rise correction for calculating a representative value of the image data of each area divided in this way is performed.

Next, the typical value of the image data in each area, the temperature of the thermal head 66 (base 66d of the heat sink) detected by the thermistor, the ambient temperature detected by the thermometer T, etc. The predicted temperature value is calculated from the value. As a method of calculating the predicted temperature value, the heat transfer system of the thermal head 66 is replaced with an equivalent circuit of an electric system based on a CR model including a capacitance component C and a resistance component R, and the heat generation amount per unit time of the heat transfer system is calculated. , Temperature, heat capacity, and heat resistance are replaced with electric current, voltage, capacity, and resistance of the electric system, respectively. From the obtained predicted temperature value, the temperature correction value for each area is calculated using a preset calculation formula, the temperature correction value for the region is interpolated, and one screen is displayed using the preset calculation formula. The temperature correction value for each pixel of the recorded image is calculated and the temperature of the image data is corrected using this value. The method of correcting the temperature rise described above is described in detail in Japanese Patent Application No. 8-25035 by the present applicant.

In the thermal recording apparatus, the image data supplied from the image data supply source R is subjected to such respective corrections to obtain thermal recording image data corresponding to the thermal recording by the thermal head 66. Here, in the recording apparatus 10 according to the present invention, each of the above corrections is performed in the order of sharpness correction and gradation correction → shading correction and resistance value correction → temperature rise correction, and any correction after gradation correction. The image data representative value calculation process for temperature rise correction is performed before or after, and the shading correction, the resistance value correction, and the temperature rise correction are further performed depending on the required image quality level. At least one of the black ratio correction and the load variation correction is performed.

As is clear from the above description of the respective corrections (image processing), the sharpness correction and the gradation correction are corrections corresponding to the image itself to be recorded, and the supplied image data (illustrated example) is used. Then, for example, 10bit (0-102
This is a correction in which each correction amount varies according to (3) digital data), that is, the correction amount is determined by the image data.
On the other hand, shading correction and resistance correction are
It corrects the density unevenness peculiar to the recording device 10,
This is reflected in the image data and corrected. The black ratio correction is a correction according to the voltage drop of the thermal head 66, and the load variation correction is a correction according to the combination of the heat-sensitive material A and the recording device 10 (thermal head 66). Is preferably performed as late as possible, and is preferably performed on the image data immediately before the final image data supplied to the thermal head 66.

As described above, the temperature rise correction detects the ambient temperature and the temperature of the thermal head 66, predicts the temperature rise of the thermal head 66 using this temperature, and calculates the temperature correction value based on this. To do. Therefore, it is preferable to perform the temperature rise correction immediately before recording, that is, at the end of image processing (correction). In other words, the line for which temperature correction has been completed is recorded immediately (that is, correction calculation is performed during recording). (Known) configuration is preferred.

Therefore, if corrections specific to the apparatus, such as shading corrections, are performed prior to corrections based on image data such as gradation corrections and sharpness corrections, the result will be that the characteristics of the apparatus will affect the target image itself. , The formed image is different from the intended image. In other words, a correction such as shading correction for eliminating streaks and the like peculiar to the recording apparatus 10 is reflected in the image data before the correction according to the recorded image (image data) itself is performed, and as a result, the recording is performed. The sharpness correction and gradation correction according to the image also reflect the device characteristics, and it is not possible to perform appropriate correction. Therefore, sharpness correction and gradation correction are basically
Perform shading correction and resistance correction before
The temperature rise correction is preferably performed just before the last recording,
Further, it is preferable that the black ratio correction and / or the load variation correction be performed in the latest order.

Here, the gradation of the recorded image changes depending on the sensitivity and gradation of the heat-sensitive material A and the characteristics of the recording device 10. Therefore, when the sharpness correction is performed after the tone correction, the sharpness correction amount changes depending on the combination of the heat-sensitive material A and the recording device 10 as in the above shading correction and the like, and a stable sharpness is obtained. It may not be possible to correct the degree. Therefore, in such a case, it is preferable to perform the gradation correction after the sharpness correction.

By the way, in gradation correction, since the temperature difference of each heating element during recording, and hence the temperature distribution of the entire thermal head, is made small to perform high-quality heat-sensitive recording, the recording density is 0 (that is, image). Even if the value of the image data input from the data source is 0), a predetermined recording data value E ₀ (E) is applied so as to apply recording energy to the extent that the heat-sensitive material A does not develop color (preferably immediately before color development). ₀
> 0).

Therefore, when the sharpness correction is performed after the gradation correction, as shown in FIG. 4A, the density of the contour or the like is high in one line in the main scanning direction of the image to be recorded. A portion (hereinafter, referred to as an edge portion) where the recording data value D _H on the side of the recording medium changes rapidly to the recording data value D _L on the side of low density
After the sharpness correction, as shown in FIG. 4B, the density difference at the edge portion is emphasized and the print data value D _L on the low density side is E ₀ or a value close to E ₀ after the sharpness correction. In some cases, the emphasized peak value D _LP of the recorded data value D _L on the low density side may be considerably smaller than E ₀ . Therefore, in the actual recorded image, even if the emphasized edge portion is relaxed due to the diffusion of heat at the edge portion, the color-developed portion is not sufficiently colored and the non-colored portion remains. Therefore, Fig. 4
As shown in (c), there is a possibility that a false contour appears as if the contour is white, and that the recorded image feels strange.

Occurrence of such false contours in a recorded image may be a serious problem when high-quality image recording is required, particularly in the case of recording a high-definition halftone image. In particular, in applications requiring high-definition and high-quality halftone images, such as the above-mentioned medical applications, it may become an obstacle to image observation and may cause a serious problem that may lead to medical errors.

In such a case, in the present invention,
With respect to the recording data D thus sharpened,
A process of converting the recording data D that is less than the predetermined value into a predetermined value (hereinafter referred to as false contour reduction process) is performed. Specifically, all the print data D smaller than the value kE ₀ obtained by multiplying the print data value E ₀ corresponding to the image data value 0 by a constant k (k <1) among the print data D after the sharpness correction. By converting to kE ₀ , generation of false contour is prevented.

FIG. 3 is a schematic diagram showing an example of conversion processing according to another aspect of the heat-sensitive recording method of the present invention. FIG. 3A shows an example of print data in the main scanning direction after gradation correction and before sharpness correction, and FIG. 3B shows print data immediately after sharpness correction to the print data in FIG. An example of FIG.
(C) is an example of recorded data after the false contour reduction processing of the present invention is applied to the recorded data of (b). Figure 3 (d) shows
It is an example of a thermosensitive recording image formed based on the pattern of the recording data of (c). An example of the thermal recording method according to another aspect of the present invention will be described below with reference to FIG. First, assume that tone correction is performed on image data input from an image data source, and a pattern of print data D in the main scanning direction as shown in FIG. 3A is obtained. Here, FIG.
In the central portion of the pattern of the print data D in (a), there is an edge portion where the print data value (that is, the density) changes abruptly.

Next, when the above-described sharpness correction is applied to a series of recording data D having such edge portions, as shown in FIG. 3B, the recording data with the edge portions emphasized is obtained. A pattern of D is obtained. That is, the image data value D _L of the low-density side of the vicinity of the edge portion (small end of the image data value) is converted highlighted into smaller peak value D _LP, the peak downward (low concentration direction) in the edge portion formed Is done. On the other hand, the image data value _DH on the high density side (the side with the larger image data value) near the edge portion is emphasized and converted into a larger peak value _DHP , and a peak is formed upward (high density direction) at the edge portion. Is done. Here, if the data of FIG. 3B is to be recorded by the thermal head as it is, as shown in FIG. 4C, the low-density-side peak portion (that is, the edge portion) also dissipates heat. Regardless, as described above, there is a case where no color is generated, a white outline appears, and a false contour is generated.

Therefore, in this embodiment, the image data D after the sharpness enhancement processing is converted as follows, and the minimum value of the recording data value D is set to kE ₀ .
As shown in FIG. 3C, the recording data after the sharpness correction is prevented from becoming an unnecessarily small value, and the heat is diffused at the edge portion in the actual recorded image, as shown in FIG. 3D. As described above, it is possible to express the contour vividly without causing a false contour.

[0070]

(Equation 8)

This conversion is performed on all image data. _Dm is the maximum value of the recording data and may be determined as appropriate. Here, as the value of k,
It is preferably 0.5 to 0.9, more preferably 0.6 to 0.7, but may be appropriately determined according to the performance of the thermal head to be used, the characteristics of the heat-sensitive recording material, and the like. Not limited. If it is less than 0.5, the false contour may not be sufficiently removed, so if it exceeds 0.9, the sharpness may not be sufficiently improved, and sufficient image quality may not be obtained. Not preferable. As described above, in this embodiment, the gradation correction is first performed, the sharpness correction is then performed, and the false contour reduction process is performed, and then the image data for the shading correction, the resistance value correction, or the temperature rise correction is performed. It is preferable to perform a representative value calculation process.

Either the shading correction or the resistance value correction may be performed first, but when the correction depends on the image data, that is, the image density, it is preferable to perform the one having a large image density dependency first. . Like above-mentioned,
Shading correction and resistance correction are corrections that multiply image data by a correction coefficient (shading correction data and resistance correction data) that is determined for each pixel (for each heating element), so correction that has a large concentration dependency is performed. It is possible to reduce the influence on the correction due to the density, if it is performed first. Generally, the shading correction has a greater density dependency than the resistance correction, and therefore the shading correction and the resistance correction are usually performed in this order. If the two have the same concentration dependence, either one may be performed first. Further, as described above, since both corrections are multiplications of correction data, both corrections may be performed at the same time (preferably, when both density dependences are equivalent).

Since both the shading correction data and the resistance correction data are unique to the thermal head 66, correction data is created in advance according to the thermal head 66, and when the thermal head 66 is replaced,
It is preferable to be able to input (load) to the recording device 10 (data storage unit 86) using an IC card, an FD or the like.

Either of the black ratio correction and the load variation correction may be performed first, and which one should be performed first may be appropriately determined depending on the combination of the heat-sensitive material A and the recording apparatus 10. Therefore, the heat-sensitive material A and the recording device 1
For one combination with 0, change the order of these corrections and actually perform a test print (test recording),
It may be determined to have a better thermal recording.

As described above, the temperature rise correction must be performed at the very end because the actual correction amount is large, but the image data is divided into areas (blocks) of a certain size, and each block is divided into blocks. The temperature is predicted and calculated and corrected. For this reason, the heat generation amount of each block is obtained by the image data representative value calculation processing, but this must accurately represent the heat generation amount of each block. Therefore, the image data representative value calculation process must always be performed after gradation correction, and is preferably performed before resistance value correction, black ratio correction, and load fluctuation correction. The image data representative value calculation process may be performed before or after the sharpness correction. Further, this image data representative value calculation processing may be performed before or after shading correction, and which is to be performed can be appropriately determined depending on the person who actually performs the correction and can perform the test print. Here, when high quality is not required for the heat-reproduced image, the prediction accuracy is slightly deteriorated, but it is performed somewhere after gradation correction even before resistance value correction, black ratio correction or load fluctuation correction. It is also possible.

However, as is clear from the above explanation,
The black ratio correction, the load variation correction, and the temperature rise correction require a large amount of calculation, and the calculation capacity and the processing timing of the image processing unit 80 (for example, first, all correction calculations are not completed and recording is performed, but recording is performed). And when performing the calculation in parallel)
Depending on the correction amount, it may be difficult to perform the black ratio correction and the load variation correction before the temperature rise correction, which needs to be performed last, because the correction amount is large. Here, the correction amount of the image data by the black ratio correction and the load fluctuation correction is relatively small, and particularly when the power supply capacity of the thermal head 66 is large (that is, the internal resistance of the power supply is small), the voltage fluctuation due to the black ratio It is small, and the torque fluctuation of the carry motor, that is, the load fluctuation is small depending on the type and size of the heat sensitive material A and the pressing force of the thermal head 66 against the heat sensitive material A. The correction amount is extremely small. Therefore, either one or both of the black ratio correction and the load variation correction may be omitted depending on the desired image quality level.

As described above, image correction (image processing) is performed in the order of sharpness correction and gradation correction → shading correction and resistance value correction → temperature rise correction, and before any image processing after gradation correction. Alternatively, the image data representative value calculation process for the temperature rise correction is performed in a predetermined order, and if necessary, the black ratio correction and / or the black ratio correction and / or the shading correction and the resistance value correction and the temperature rise correction are performed. Alternatively, according to the recording apparatus 10 of the present invention in which the load variation correction is performed, all the corrections can be appropriately performed and the expected correction effect can be sufficiently obtained, so that the thermosensitive recording image data that has been appropriately image-processed can be used. It is possible to stably record a high quality heat sensitive image.

As described above, the image data from the image data supply source R such as CT or MRI is supplied to the image processing section 80 of the recording apparatus 10. This image data is sent from the image processing unit 80 to the data storage unit 86, formatted as necessary and stored. When the image data is stored in the data storage unit 86, first, the image processing unit 80 reads out necessary data from the data storage unit 86, and all the image data stored in the data storage unit 86 before the start of thermal recording. Sharpness correction, then gradation correction, or gradation correction, and then sharpness correction, and subsequently, the white false contours caused by the sharpness correction processing (enhancement) are significantly reduced. At the same time, the false contour reduction processing for vividly expressing the contour in the recorded image is performed, and then the processed image data is stored again in the data storage unit 86. Upon completion of these correction processes, thermal image recording is started. While the image processing unit 80 reads out necessary data from the data storage unit 86, in the image data stored in the data storage unit 86, in the order of performing image recording from the image data of the first line in which image recording is performed first. The thermal recording data corresponding to the thermal recording by the thermal head 66 is performed line by line sequentially in the predetermined order, including shading correction, resistance value correction, black ratio correction, load fluctuation correction, and finally temperature rise correction. And At this time, the image data representative value calculation process for the temperature rise correction may be performed before or after the start of recording as long as it is after the gradation correction.

The recording control unit 84 sequentially reads the thermosensitive recording image data of all the corrected lines from the data storage unit 86 line by line, and outputs a recording signal (corresponding to the image) corresponding to the read thermosensitive recording image data. The voltage application time width) is output to the thermal head 66. Each heat generating element of the thermal head 66 generates heat in response to the recording signal, and as described above, the heat sensitive image is recorded while the heat sensitive material A is conveyed by the platen roller 60 or the like in the arrow b direction.

In the recording apparatus 10 of the present invention, in the above-mentioned predetermined order, after the thermosensitive recording image data in which all the corrections have been completed for all the image data are stored in the data storage section 86 (that is, the image to be recorded). After creating the data)
Alternatively, the image recording may be started by reading the data from the data storage unit 86 line by line. However, the above configuration, that is, the configuration in which the recording is started after the sharpness correction and the gradation correction are performed in advance, and the correction calculation is performed while the recording is performed thereafter, can significantly reduce the recording time. .

The heat-sensitive material A on which the heat-sensitive image recording has been completed is guided by the guide 62, is conveyed to the platen roller 60 and the pair of conveying rollers 63, and is ejected to the tray 72 of the ejecting section 22. The tray 72 protrudes outside the recording apparatus 10 through a discharge port 74 formed in the housing 28, and the heat-sensitive material A on which an image is recorded is discharged to the outside through the discharge port 74 and is taken out.

Although the heat-sensitive recording method and the heat-sensitive recording apparatus of the present invention have been described above in detail, the present invention is not limited to the above examples, and various improvements and changes can be made without departing from the scope of the present invention. Of course you can go.

[0083]

As described above in detail, according to the present invention, it is possible to sufficiently obtain an expected correction effect for all image processing (correction) performed in thermal recording using a thermal head. Therefore, it is possible to stably record a high-quality heat-sensitive image by the heat-sensitive recording image data that has been properly image-processed.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an example of a thermal recording apparatus of the present invention.

FIG. 2 is a conceptual diagram of a recording unit of the thermal recording apparatus shown in FIG. 1 and a block diagram of a control system of the recording unit.

FIG. 3 is a schematic diagram illustrating an example of a conversion process according to the thermal recording method of the present invention. (A) is an example of print data in the main scanning direction after gradation correction and before sharpness correction, (b)
(A) is an example of the recording data immediately after performing the sharpness correction on the recording data of (a), (c) is an example of the recording data after performing the false contour reduction processing of the present invention on the recording data of (b), ( d)
FIG. 9C is an example of a thermal recording image formed based on the pattern of the recording data in FIG.

FIG. 4 is a schematic diagram showing an example of a conversion process by a conventional thermal recording method. (A) is an example of print data in the main scanning direction after gradation correction and before sharpness correction, (b) is an example of print data immediately after sharpness correction is performed on the print data of (a), (c) () Is an example of a thermal recording image formed based on the pattern of the recording data of (b).

[Explanation of symbols]

 10 (Thermal Image) Recording Device 14 Loading Unit 16 Supply Conveying Unit 20 Recording Unit 22 Ejecting Unit 24 Magazine 26 Lid 28 Housing 30 Insertion Port 32 Guide Plate 34 Guide Roll 36 Stopping Member 40 Sucker 42 Conveying Means 44 Conveying Guide 48 Endless Belt 50 Nip Roller 52 Control Roller Pair 56 Cleaning Roller Pair 58, 62 Guide 60 Platen Roller 63 Conveying Roller Pair 66 Thermal Head 68 Supporting Member 72 Tray 74 Ejection Port 76 Cooling Fan 80 Image Processing Section 84 Recording Control Section 86 Data Storage Section A Thermal ( Record) material

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area H04N 1/40 101Z

Claims (12)

[Claims] 1. A thermal recording method, wherein predetermined image processing is performed on image data supplied from an image data supply source, and a thermal head is driven according to the processed image data to perform thermal recording. The processing is first sharpness correction and gradation correction, then shading correction and resistance value correction, finally temperature rise correction, and before or after any of the processing after gradation correction. A thermal recording method, characterized in that a representative value calculation process of image data for correction of increase is performed in a predetermined order. 2. The thermal recording method according to claim 1, wherein after the shading correction and the resistance value correction and before the temperature rise correction, a black ratio correction and / or a load variation correction are further performed. 3. The thermal recording method according to claim 1, wherein the gradation correction is performed after the sharpness correction. 4. The thermal recording method according to claim 1, wherein the sharpness correction is performed after the gradation correction is performed. 5. Shading correction and resistance correction are
A correction having a higher image density dependency is performed first, and if the image density dependency of both corrections is equivalent, an arbitrary order or shading correction and resistance correction are performed simultaneously.
4. The heat-sensitive recording method according to any one of 4 to 4. 6. The thermal recording method according to claim 2, wherein the black ratio correction is performed before the load variation correction. 7. A thermal head having a glaze formed by arranging heating elements in one direction, and the thermal head and the thermal recording in a direction orthogonal to the arrangement direction of the heating elements by contacting the glaze with the thermal recording material. The means for moving the material relative to each other and the image data supplied from the image data supply source are first subjected to sharpness correction and gradation correction, followed by shading correction and resistance value correction, and finally temperature rise correction. Image processing means for performing representative value calculation processing of image data for temperature rise correction before or after any processing after gradation correction, and image data processed by the image processing means. Based on the above, there is provided recording control means for driving the thermal head. 8. The image processing means, after the shading correction and the resistance value correction, and before the temperature rise correction,
The thermal recording apparatus according to claim 7, which further performs black ratio correction and / or load fluctuation correction. 9. The thermal recording apparatus according to claim 7, wherein the image processing means performs the gradation correction after the sharpness correction. 10. The thermal recording apparatus according to claim 7, wherein the image processing means performs the sharpness correction after the gradation correction. 11. The image processing means first performs one of the shading correction and the resistance value correction, whichever has a higher image density dependency. If the image density dependency of both corrections is equivalent, the correction is arbitrary. The thermal recording apparatus according to any one of claims 7 to 10, wherein the order of or the shading correction and the resistance value correction are simultaneously performed. 12. The image processing means performs the black ratio correction before the load variation correction.
The thermal recording device according to any one of 1.