JP6784742B2 - Information processing equipment and its method - Google Patents

Description

The present invention relates to a process for recovering the sharpness of an image formed by an image forming apparatus.

It is known that in an image output by an image forming apparatus, the sharpness of the image is lowered due to the deviation of the landing position of the ink, the blurring of the ink, the optical blur (optical dot gain), and the like. If the frequency characteristic of the sharpness reduction of the output image (hereinafter referred to as the sharpness reduction characteristic) can be acquired, the sharpness reduction can be canceled by the recovery filter processing having the opposite characteristic.

However, the characteristics of reduced sharpness include the type of image forming device (injection method, electrophotographic method, etc.), model, type of recording medium (recording paper), output conditions, light source distribution (angle, orientation) during image observation, etc. Depends on. For example, in the case of an inkjet image forming apparatus, the sharpness reduction characteristic changes depending on the ink bleeding depending on the type of ink (dye, pigment), the optical dot gain at the time of observation, the recording medium, and the like.

Patent Document 1 describes a technique for performing sharpness recovery processing using a sharpness recovery filter that differs depending on the recording medium, ink type, input device, and subject portion. In this technique, there is a one-to-one correspondence between the sharpness reduction characteristic of the output image and the sharpness recovery filter. As a result, it is necessary to maintain a sharpness recovery filter for all combinations of output conditions such as recording medium, ink type, number of passes, carriage speed, scanning direction (bidirectional or unidirectional printing), halftone processing, etc. There is, and it is not realistic.

Further, the technique of Patent Document 1 cannot cope with an unknown recording medium (unregistered recording medium) at all. Further, the appearance of sharpness (decreased characteristic) of the output image differs depending on the illumination position when observing the image, but the technique of Patent Document 1 is not considered in this regard.

Japanese Unexamined Patent Publication No. 2013-61925

An object of the present invention is to reduce the holding amount as compared with the case where the recovery processing parameter is held for all combinations of output conditions.

The present invention includes the following configurations as one means for achieving the above object.

The information processing apparatus according to the present invention includes a condition acquiring means for acquiring the output conditions of the image forming unit, a lookup table for holding in association with each of a plurality of output conditions on the restoration filter to recover the sharpness of the image The recording of the frequency response value to the periodic pattern of a specific frequency in the image formed on the recording medium by the image forming unit under the output conditions acquired by the condition acquisition means, which is determined to have no corresponding record. Based on the frequency response value acquisition means acquired based on the information acquired from the measurement chart including the periodic pattern of the specific frequency formed on the medium, and the output conditions and the frequency response values acquired by the condition acquisition means. , to the look-up table holding in association with each of a plurality of output conditions on the restoration filter to recover the sharpness of the image, before is determined that the corresponding record is not present the said condition acquiring means acquires Kide a force condition, having a registration means for registering in association with the recovery filter.

According to the present invention, it is not necessary to hold recovery processing parameters for all combinations of output conditions.

The block diagram which shows the structural example of the image processing apparatus of an Example. The flowchart explaining the outline of processing in an image processing apparatus. The figure which shows an example of the linkage LUT. The figure which shows an example of the spatial frequency characteristic when an image is output under a certain output condition. A flowchart illustrating a process of creating a linked LUT. The figure which shows an example of the measurement chart. The figure which shows the visual characteristic calculated by a known method. The figure which shows an example of the linkage LUT before making substantially the same judgment. A flowchart illustrating the process of creating a recovery filter. The figure which shows an example of the linkage LUT of Example 2. The figure which shows an example of the UI suitable for the linkage LUT having a hierarchical structure. The figure which shows the change example of the sharpness decrease when the angle and direction of a light source with respect to an image are changed. The flowchart explaining the outline of processing in the image processing apparatus of Example 3. The figure which shows an example of UI for specifying the direction Ld of a light source. The figure which shows an example of UI for specifying the angle La of a light source. The figure which shows an example of the linkage LUT in Example 3. FIG. The flowchart explaining the processing in the image processing apparatus of Example 4. The figure which shows an example of the measurement chart of a specific frequency pattern. The figure explaining the selection of a recovery filter and the frequency response value after a recovery process. The flowchart explaining the processing in the image processing apparatus of Example 5. The figure which shows the measurement chart of a rectangular pattern and an example of the influence range of a dot gain. The figure which shows the anisotropy of bleeding when the light source condition is different.

Hereinafter, the image processing and information processing of the examples according to the present invention will be described in detail with reference to the drawings. It should be noted that the examples do not limit the present invention in the scope of claims, and not all combinations of configurations described in the examples are essential for the means for solving the present invention.

FIG. 7 shows the visual characteristics calculated by a known method (Dooley's approximation formula). However, the observation distance is 300 mm. As shown in FIG. 7, the sensitivity characteristic of human vision (hereinafter referred to as visual characteristic) decreases as the spatial frequency increases. For example, in the spatial frequency range (hereinafter, frequency range) exceeding 4 cycles / mm, the visual characteristics become 0.25 or less, and even if a decrease in sharpness occurs, it is difficult to recognize it. In the following, the spatial frequency (for example, 4 cycles / mm) that makes it difficult to recognize the decrease in sharpness will be referred to as the "visual limit frequency". Further, in the following, the spatial frequency may be simply referred to as "frequency".

In the first embodiment, when the output condition and the table for linking the recovery filter corresponding to the output condition are provided and the reduction characteristics of the sharpness in the frequency range below the visual limit frequency can be regarded as substantially the same, they are standardized. An example of performing sharpness recovery processing using a recovery filter will be described.

[Outline of device configuration and processing]
A configuration example of the image processing device 100 of the embodiment is shown by a block diagram of FIG. 1, and an outline of processing in the image processing device 100 is described by a flowchart of FIG. The recovery processing unit 107 inputs the image data i to be image-formed from the information processing device 150 or the like via the data input / output unit (i / o) 104, and the input image data i is used as a memory unit 101 such as RAM. Store in (S201).

The condition acquisition unit 103 acquires the output condition Oi of the image forming unit 108 via the user interface (UI) unit 102 or from the information processing device 150 (S202). Output condition Oi items include number of passes, carriage speed, print direction (bidirectional or unidirectional), halftone pattern, distance between print head and recording medium, use of clear ink, color setting, silent setting. Presence / absence, type of recording medium, etc. are included. Clear ink (hereinafter, CL ink is an ink containing a colorless and transparent or substantially colorless and transparent pigment.

Next, the filter selection unit 106 accesses the parameter holding unit 105 to acquire the recovery filter Ri corresponding to the output condition Oi (S203). The recovery processing unit 107 executes sharpness recovery processing by the recovery filter Ri on the input image data i, and stores the image data i'after the recovery processing in the memory unit 101 (S204). Then, the image forming unit 108 forms the image represented by the image data i'after the recovery process on the recording medium 208 based on the output condition Oi (S205).

● Image forming unit The color separation unit 201 of the image forming unit 108 refers to the color separation table, and corresponds to, for example, the RGB format image data i'corresponding to the ink color (and CL ink if necessary) provided in the image forming unit 108. Color-separates into the amount data to be used. The halftone (HT) processing unit 202 uses a halftone pattern (hereinafter, HT pattern) to quantize the quantized data output by the color separation unit 201, and records the quantized data after the HT processing (hereinafter, HT pattern). Output as HT data).

The image forming unit 108 is a recording device such as a thermal transfer method or an inkjet method, and moves the recording head 205 vertically and horizontally with respect to the recording medium 208 to record an image indicated by HT data input in band units. Formed on medium 208. At that time, the ink color selection unit 203 selects the ink color corresponding to the input HT data from the ink colors mounted on the recording head 205.

The recording head 205 has one or more recording elements (nozzles in the case of an inkjet method). For the relative vertical and horizontal movement of the recording head 205, the head control unit 204 controls the moving unit 206 to move the recording head 205 in the X direction (main scanning direction), and the head control unit 204 controls the transport unit 207. This is achieved by transporting the recording medium 208 in the Y direction (secondary scanning direction).

● Parameter holding unit The parameter holding unit 105 is, for example, a non-volatile memory such as an EEPROM or a flash memory, and holds a look-up table (hereinafter referred to as a linked LUT) linked with a combination of output conditions described above and a recovery filter. Fig. 3 shows an example of the linked LUT, and Fig. 4 shows an example of the spatial frequency characteristics when an image is output under certain output conditions.

In FIG. 4, the frequency characteristics f1-f5, fa, fb, and fc correspond to the output conditions O1-O5, Oa, Ob, and Occ shown in FIG. 3, respectively. For example, the same recovery is applied to output conditions such as output conditions O1-O5 and Ob, which can be regarded as having substantially the same frequency characteristic f in the low frequency region (hereinafter, important region) which is important (high sensitivity) in terms of visual characteristics. It is possible to use filters. The details of the frequency characteristic calculation method corresponding to the output conditions will be described later.

● Information processing device The image processing device 100 is connected to the information processing device 150, which is a computer device such as a personal computer. A serial bus such as USB, a wired or wireless network, or the like can be used to connect the image processing device 100 and the information processing device 150.

The CPU 151 of the information processing device 150 uses the RAM 154 as a work memory to execute the OS and various programs stored in the ROM 153 and the storage unit 155, and controls the operation of the information processing device 150. A printer driver, a creation program that realizes a function of creating a linked LUT and a recovery filter, and the like are stored in a storage unit 155 such as an HDD or SSD. The CPU 151 that executes the printer driver supplies image data to the image processing device 100 via a general-purpose interface 152 such as USB or a wired or wireless network. In addition, the CPU 151 that executes the creation program creates the linked LUT and recovery filter held by the parameter holding unit 105 via the general-purpose interface 152 or a wired or wireless network.

Further, when the image processing device 100 is a multifunction device equipped with a scanner, a CPU (not shown) of the image processing device 100 is made to execute a creation program for creating a linked LUT and a recovery filter to create a linked LUT and a recovery filter. It is also possible to do it.

[Factors of reduced sharpness]
The sharpness of the image output by the image forming unit 108 changes due to the influence of the ink landing position shift, the ink bleeding, the optical dot gain, and the frequency characteristics of the HT pattern. Then, the ink landing position shift, the ink bleeding, the optical dot gain, and the frequency characteristics of the HT pattern change depending on the output conditions of the image forming unit 108. Therefore, the sharpness of the output image differs depending on the output conditions of the image forming unit 108. That is, when the output conditions O1-O5, Oa, Ob, and Occ shown in FIG. 3 are used, the frequency characteristics become different frequency characteristics f1-f5, fa, fb, and fc as shown in FIG.

For example, when the number of passes is different as in the output conditions O1 and O2, the amount of ink ejected in one pass changes, and when the number of passes is small, the dot adhesion rate and the time required for fixing become relatively large. The amount of ink bleeding increases. Further, if the number of passes is small, streaky density unevenness occurs due to the positional deviation of each discharge nozzle, but there is little blurring due to the phase shift in terms of frequency characteristics (the decrease in sharpness is small). On the contrary, when the number of passes is increased, the influence of the misalignment of each discharge nozzle is alleviated and the uneven density of the streaks is reduced, but the sharpness is lowered (blurring is increased). In this way, even if the number of passes is changed, the frequency characteristics of the output image change, for example, f1 and f2.

In addition, when the carriage speed is changed as in the output conditions O1 and O3, the relative positions of the main droplet (droplet forming the concentration) and the droplet other than the main droplet (hereinafter, satellite) shift. Since the discharge speeds of the main droplet and the satellite are different, the relative positional deviation between the main droplet and the satellite (hereinafter referred to as the master-slave deviation) increases as the carriage speed increases. In addition, the ink bleeding changes. For example, when the carriage moves quickly, the interval between passes is small, so that the next ink is likely to land before the ink is dried, and the ink is likely to bleed. When the carriage speed is changed in this way, the master-slave deviation and the blur change, and as a result, the frequency characteristics of the output image change, for example, f1 and f3.

Similarly, if the output conditions O1 and O4 are different in terms of unidirectional printing, which prints only on the outward path of the recording head 205, and bidirectional printing, which prints on the outward and return paths of the recording head 205, registration The amount of deviation and the interval between passes are different. As a result, the frequency characteristics of the output image change, for example, f1 and f4.

Further, in the case of an HT pattern having many adjacent dots in the path, such as output conditions O1 and O5, the dots are likely to be connected to each other and the bleeding is likely to increase. Further, since the HT pattern itself has a frequency characteristic and the image output by the image forming unit 107 is quantized by the HT pattern, the frequency characteristic of the output image depends on the frequency characteristic of the HT pattern, for example, f1 and f5. Changes to.

Further, when the distance between the recording head 205 and the recording medium 208 (hereinafter referred to as the head distance) is short, the deviation of the landing position is reduced. Further, when a pigment-based ink is used, overcoating with CL ink may be performed in order to reduce gloss unevenness and coloring, and the refractive index of the output image surface changes, so that the optical dot gain changes. Further, when the color settings such as the ink saving mode, the monochrome mode, and the saturation are changed, the ejection amount of each ink changes. Therefore, the bleeding differs depending on the ink saving mode and the color setting. Therefore, the frequency characteristics of the output image change, for example, f1 and fa, depending on the head distance, the presence or absence of CL ink used, and the color setting as in the output conditions O1 and Oa.

Further, the characteristic of reducing the sharpness of the output image changes depending on the ink bleeding and the optical dot gain depending on the recording medium 208. In particular, the frequency characteristics change depending on the thickness of the receiving layer of the recording medium 208 and the particle size of the material forming the receiving layer (hereinafter, the particle size of the receiving material). When the particle size of the receiving material is large, the light incident on the recording medium 208 is difficult to diffuse, and as a result, the blurring due to the optical dot gain becomes small. Further, the receiving layer and the supporting layer of the recording medium 208 have different light diffusivity due to the difference in material and structure, and as a result, the optical dot gain also differs depending on the thickness of the receiving layer. The thickness of the receiving layer and the particle size of the receiving material are also related to the penetration rate of the ink and the absorption limit of the ink. Therefore, if the type of the recording medium 208 is different, such as the output conditions O1, Ob, and Oct, the frequency characteristics of the output image will change, for example, f1, fb, and fc.

In this way, the frequency characteristics of the output image produced by the image forming unit 107 change depending on the output condition Oi. Therefore, in order to perform the best recovery processing in the frequency domain (important range) recognizable by the human eye, the parameter holding unit 104 holds the parameters of the recovery filter corresponding to all combinations of the output condition O described above. There is a need. The number Nc of combinations is, for example, as follows.
Nc = number of passes x number of carriage speeds x number of bidirectional printing on / off x number of HT patterns x number of head distances x number of CL inks on / off x silent mode on / off x ink-saving mode on / off x monochrome mode on / off x recording medium Number of types

In Fig. 3, Nc is 2 (number of passes) x 2 (carriage speed) x 2 (bidirectional printing) x 2 (HT pattern) x 2 (head distance) x 2 (using CL ink) x 2 (silent mode) x 2 (Ink saving mode) x 2 (monochrome mode) x 3 (type of recording medium) = 384. In other words, the parameter holding unit 104 needs to hold a number of recovery filters equal to the number of combinations (for example, 384) as recovery processing parameters, which requires a large amount of memory.

In the first embodiment, the parameter holding unit is created by acquiring the frequency characteristic f for each output condition and creating a linked LUT that assigns the same filter number to the output conditions having substantially the same reduction characteristic of sharpness in the important region. Suppress the amount of memory of 105.

For example, among the frequency characteristics f1-f5, fa, fb, and fc shown in FIG. 4, it can be determined that the sharpness reduction characteristics of f1-f5 and fb in the important region are substantially the same. In this case, the same filter number (“1” in the example of FIG. 3) is assigned to the output conditions O1-O5 and Ob corresponding to f1-f5 and fb of the linked LUT. Furthermore, when a reduction in the amount of memory is required, the same filter number is assigned to the output condition Oa corresponding to, for example, fa. On the contrary, if there is a margin in the amount of memory, in order to improve the accuracy of the recovery process, different filter numbers (for example, "4") are used for the output condition Ob, which has different frequency characteristics from the output conditions O1-O5 and the most important region. ) May be assigned.

[Create linked LUT]
The process of creating the linked LUT will be described with reference to the flowchart of FIG. By the process shown in FIG. 5, a linked LUT is created in which the same filter number is assigned to the output conditions that can be regarded as having substantially the same frequency characteristics in the important region (particularly the frequency region below the visual limit frequency). The process shown in FIG. 5 is realized by executing the linked LUT creation program in the information processing device 150. The details of how to create the recovery filter will be described later.

The CPU 151 initializes the counter i to "1" (S500), and acquires the output condition Oi by referring to the linked LUT stored in the parameter holding unit 105 (S501). For example, as the output condition O1 in Fig. 3, the recording medium "A", the number of passes "32", the carriage speed "slow", the printing direction "unidirectional", the HT pattern-"HT1 (error diffusion)", the head distance " "Short", clear ink "none", and color setting "color" are acquired.

Next, the CPU 151 controls the image forming unit 108 and outputs a sharpness measurement chart according to the output condition Oi (S502). Needless to say, the recovery process is not performed when the measurement chart is output. Figure 6 shows an example of the measurement chart. The measurement chart is an image chart including a plurality of sine wave patterns having different frequencies and a uniform pattern (for example, solid white and solid black) at the lower left.

Next, the CPU 151 acquires the information necessary for acquiring the frequency characteristics from the measurement chart by using a measuring device (not shown) connected to the general-purpose interface 152 (S503). Then, based on the acquired information, the frequency response value fi (u) for the output condition Oi is calculated (S504). As the frequency response value fi (u), for example, the absolute value MTF (u) of the optical transfer function calculated by using the following equation can be used.
fi (u) = MTF (u) = C (u) / C'… (1)
Where u is the frequency of the sine wave,
C (u) = {Max (u) -Min (u)} / {Max (u) + Min (u)},
C'= (White-Black) / (White + Black),
Max (u) is the maximum reflectance of a sinusoidal pattern that changes with frequency u,
Min (u) is the minimum reflectance of a sinusoidal pattern that changes with frequency u,
White and Black each have a uniform pattern reflectance.

Of course, the calculation of MTF (u) is not limited to the equation (1), and the following equation may be used, for example.
fi (u) = MTF (u) = {Max (u) -Min (u)} / (White-Black)… (1')

In equation (1), when the average brightness of the output image changes according to the frequency u of the sine wave, the response value becomes excessive in the dark part with respect to the bright part. Therefore, when the average brightness of the output image changes, it is preferable to use the equation (1') rather than the equation (1). Although Max (u) and Min (u) and White and Black are described as reflectances, for example, brightness, density, and device RGB values may be used. Further, as a measuring device for acquiring information necessary for acquiring frequency characteristics such as Max (u) and Min (u), White and Black, for example, a scanner, a digital camera, a microscope, a microdensitometer or the like can be used. it can.

Further, as a measurement chart, the frequency characteristic fi (u) may be acquired by using a square wave pattern instead of the sine wave pattern. In that case, the value of the contrast transfer function (CTF) calculated by applying the equation (1) to the rectangular wave pattern may be used for the frequency characteristic fi (u). Alternatively, the MTF value obtained by converting the CTF value using a known Coltman correction formula may be used for the frequency characteristic fi (u). Alternatively, as the frequency characteristic fi (u), a subjective evaluation value of sharpness with respect to the spatial frequency pattern may be used.

Next, the CPU 151 determines whether or not there is a filter number that can be assigned to the output condition Oi based on the frequency characteristic fi obtained by concatenating the calculated frequency response values fi (u) (S505). As a result of the determination, if the output condition Oi has a filter number that can be assigned, the process proceeds to step S506, and if there is no filter number that can be assigned to the output condition Oi, the process proceeds to step S507.

The filter number that can be assigned to the output condition Oi is the filter number corresponding to the frequency characteristic that can be regarded as substantially the same as fi among the acquired frequency characteristics f1 to fi-1. That is, it is determined whether or not the acquired frequency characteristic f1 to fi-1 can be regarded as substantially the same as the frequency characteristic fi. Next, among the filter numbers already stored in the linked LUT, it is determined whether or not there is a filter number corresponding to the frequency characteristic that can be regarded as substantially the same as the frequency characteristic fi, in other words, a filter number that can be assigned to the output condition Oi. Will be done.

Assuming that the acquired frequency characteristics are fo, for substantially the same determination, for example, the maximum value (or average value) of the difference between the response values of the important regions in fi and fo may be used. That is, when the maximum value (or average value) of the difference is smaller than the predetermined value, it is judged that fi and fo are substantially the same. Alternatively, if the difference between the response values at a specific frequency in the important region is smaller than the predetermined value, it may be determined that fi and fo are substantially the same. As the predetermined value, a constant value such as a measurement error, a constant multiple of the measurement error, or 0.05 can be used.

The difference is preferably the difference in the power of the frequency characteristics in the frequency range that is visually sensitive and has less noise and brightness reduction in the printer output. For example, it is preferable to judge the difference in the important region (low frequency region below the visual limit frequency).

In addition, the frequency characteristics for the spatial frequency pattern with the same frequency but different fringe directions shown in FIG. 6 are calculated, and if the difference in the important region is less than or equal to a predetermined value regardless of the fringe direction, they are regarded as substantially the same. Is preferable. It should be noted that the difference for each frequency may be weighted in consideration of the frequency characteristics of the visual system to determine whether or not they are substantially the same.

FIG. 8 shows an example of the linked LUT before making substantially the same determination in step S505. The linked LUT shown in FIG. 8 is different from the linked LUT shown in FIG. 3 in the image forming unit 107, and the filter number assignments do not match. The creation of the linked LUT shown in FIG. 8 is in the stage of i = 6, and in step S505, the determination regarding the filter number assigned to the output condition O6 is made. That is, the acquired frequency characteristics f1-f5 and the frequency characteristics f6 of the output condition O6 are judged to be substantially the same. In the example of FIG. 8, the frequency characteristics f1, f3, f4 and the frequency characteristics f6 are determined. It shows an example that is judged to be almost the same.

In this case, the frequency characteristics f3 and f4 of the output conditions O3 and O4 to which the filter number 2 is assigned substantially match the frequency characteristics f6 of the output condition O6. Therefore, the filter number 2 can be assigned to the output condition O6. On the other hand, since the filter number 1 assigned to the output condition O1 is also assigned to the output condition O2 whose frequency characteristics cannot be regarded as substantially matching, it is not determined that the filter number 1 can be assigned to the output condition O6. Of course, since the filter number 3 is assigned to the output condition O5 whose frequency characteristics cannot be regarded as substantially matching, it is not determined that the filter number 3 can be assigned to the output condition O6.

If the output condition Oi has an assignable filter number, the CPU 151 stores the assignable filter number in the record of the output condition Oi of the linked LUT (S506). When two or more filter numbers can be assigned, for example, a smaller filter number may be assigned, or a filter number corresponding to a frequency characteristic having a small difference may be assigned.

On the other hand, if there is no filter number that can be assigned to the output condition Oi, the CPU 151 stores the new filter number in the record of the output condition Oi of the linked LUT (S507). For example, among the filter numbers stored in the linked LUT, the filter number obtained by adding "1" to the largest filter number may be used as the new filter number.

Next, the CPU 151 determines whether or not there is an output condition for which the filter number has not been determined (unregistered) (S508). If there is an output condition for which the filter number is undecided, the CPU 151 increments the counter i (S509) and returns the process to step S501. As a result, the filter number is assigned to the next output condition. If there is no output condition for which the filter number has not been determined (unregistered), the CPU 151 ends the creation of the linked LUT.

When the frequency characteristics and the allocation of the filter numbers are sequentially processed according to the flowchart shown in FIG. 5, the number of recovery filters may not be minimized. For example, if there are output conditions Oe, Of, Og, and Oh, and the frequency characteristics of Oe and Of, the frequency characteristics of Of and Og, and the frequency characteristics of Og and Oh are considered to be approximately the same, the number of filters depends on the processing order. May be different. The first possibility is that the output conditions Oe and Of are assigned the filter number E, the output conditions Og and Oh are assigned the filter number G, and there are two recovery filters. The second possibility is that the output condition Oe is assigned the filter number E, the output conditions Of and Og are assigned the filter number F, the output condition Oh is assigned the filter number H, and there are three recovery filters. Is. To minimize the number of filters, after acquiring the frequency characteristics for each output condition, group the output conditions that can be regarded as having substantially the same frequency characteristics so that the number of filters is minimized based on the frequency characteristics, and then group each output condition. It is conceivable to assign a filter number to.

In the above, an example in which the CPU 151 accesses the linked LUT of the parameter holding unit 105 and performs the filter number registration process has been described. However, the CPU 151 acquires a linked LUT whose filter number is not registered from the parameter holding unit 105, the storage unit 155, or a server device (not shown), performs the filter number registration process, and then holds the linked LUT after the registration process as a parameter. It can also be stored in part 105.

[Generate recovery filter]
The purpose of the recovery process is to restore sharpness, and if the frequency characteristic after recovery exceeds 1, it is not a recovery process but an emphasis process. Further, the excessive recovery process causes adverse effects such as noise enhancement, brightness reduction, and ringing, but the adverse effects due to insufficient recovery are small. For these reasons, when performing recovery processing using a common recovery filter for a plurality of output conditions, it is preferable to generate a common recovery filter so as not to cause excessive recovery processing.

Therefore, when generating a different recovery filter for each filter number registered in the linked LUT, in order to prevent excessive recovery processing, the frequency characteristic with the minimum sharpness reduction characteristic from the frequency characteristics of multiple output conditions using the recovery filter. (Hereinafter, the minimum deterioration characteristic) is obtained. Then, the recovery filter is generated based on the minimum deterioration characteristic.

The recovery filter generation process will be described with reference to the flowchart of FIG. The process shown in FIG. 9 is realized by executing the recovery filter generation program in the information processing device 150. Further, FIG. 9 shows a process of generating a recovery filter corresponding to one filter number, but it goes without saying that the process of generating a recovery filter corresponding to the filter number registered in the linked LUT is repeated.

The CPU 151 accesses the linked LUT of the parameter holding unit 105, acquires the filter number x (S701), and determines whether or not the filter number x is assigned to a plurality of output conditions (S702). When the filter number x is assigned to a plurality of output conditions, the CPU 151 acquires the frequency characteristics fx1, fx2, ... Of the output conditions Ox1, Ox2, ... To which the filter number x is assigned (S703). Then, the frequency characteristic fx with the minimum sharpness reduction characteristic (hereinafter referred to as the minimum deterioration characteristic fx) is calculated by the following equation (S704).
fx (u) = max {fx1 (u), fx2 (u),…}… (2)
Where u is the spatial frequency,
max () is a function that outputs the maximum value.

When the filter number x is assigned to one output condition, the CPU 151 acquires the frequency characteristic of the output condition as the minimum deterioration characteristic fx (S705). When the minimum deterioration characteristic fx is obtained, the CPU 151 calculates the frequency characteristic rx of the recovery filter by the following equation (S706).
rx (u) = 1 / fx (u)… (3)

Next, the CPU 151 applies an inverse Fourier transform to the frequency characteristic rx of the recovery filter, calculates the recovery filter Rx (S707), associates the calculated recovery filter Rx with the filter number, and stores it in the parameter holding unit 105 (S708). ). When the recovery process in step S204 is performed in the frequency space, the frequency characteristic rx of the recovery filter Rx is associated with the filter number and stored in the parameter holding unit 105.

Further, it is known that when the recovery process is performed in the high frequency range, noise increases and brightness decreases. Therefore, for example, in the frequency range exceeding the visual limit frequency, which has low sensitivity in terms of visual characteristics, the value of rx (u) may be limited to a small value to reduce the amount of recovery, or rx (u) = 1 is substantially set. The recovery process may not be performed.

In this way, the recovery filter used for the sharpness recovery process is commonly created for the output conditions that can be regarded as having substantially the same frequency characteristics of the output image. At that time, the determination that the frequency characteristics are substantially the same is made by paying attention to a frequency range (for example, an important range below the visual limit frequency) that is visually important and in which a decrease in sharpness is easily visually recognized.

In addition, create a common recovery filter to prevent excessive recovery processing under all corresponding output conditions. According to such a recovery filter creation method, the memory amount of the parameter holding unit 105 is suppressed and the sharpness recovery process is appropriately performed without preparing a recovery filter for all combinations of output conditions. be able to. In other words, if the sharpness reduction characteristics of the image are visually considered to be substantially the same, the same recovery processing parameters can be used for the sharpness recovery processing, for example, for all combinations of output conditions. It is no longer necessary to hold recovery processing parameters.

Hereinafter, the image processing and information processing of the second embodiment according to the present invention will be described. In the second embodiment, the same reference numerals may be given to the configurations substantially the same as those in the first embodiment, and detailed description thereof may be omitted.

In the second embodiment, when acquiring the recovery filter, a linked LUT having a hierarchical structure is used to search for the recovery filter in order from the item of the output condition that is expected to have a large influence on the decrease in sharpness of the important area. To explain.

In Example 1, an example in which the output condition and the recovery filter are linked by one linked LUT has been described. However, the degree of influence on the decrease in sharpness of the important area differs depending on each item of output conditions such as the number of passes, the carriage speed, and the recording medium. For example, if the recording medium is different, the decrease in sharpness of the important area changes significantly, but it is assumed that the decrease in sharpness of the important area does not change significantly even if the number of passes is changed. Therefore, once the output conditions that have a large effect on the decrease in sharpness of the important region (for example, recording medium, whether or not CL ink is used, etc.) are determined, the frequency characteristics of the important region are substantially the same regardless of the settings of other items. Is likely to be decided.

In the linked LUT described in the first embodiment, records exist for each of a plurality of output conditions in which the frequency characteristics of the important region substantially match, and the number of records of the linked LUT (the number of rows in the table and the amount of memory shown in FIG. Equivalent to) increases. For example, in FIG. 3, the output conditions O1-O6 correspond to the same recovery filter, but the same recovery filter linkage requires the amount of memory for six lines. In other words, the linked LUT shown in the first embodiment stores information that can be reduced, and the amount of memory required for the parameter holding unit 105 increases by that amount, or the amount of memory of the parameter holding unit 105 is consumed.

In the second embodiment, a method of suppressing an increase or consumption of the memory amount of the parameter holding unit 105 due to the number of records of the linked LUT will be described. In other words, among the output conditions, the linked LUTs are prepared in the order of the output condition items that have a large effect on the decrease in sharpness of the important area, and the number of records of the linked LUT is suppressed by layering with a plurality of linked LUTs. ..

In recent years, printers with higher definition than 300dpi have become popular. Such a high-definition printer has a dot diameter of 30 microns or less per drop of ink and a landing accuracy of 10 microns or less, and is relatively affected by a decrease in sharpness (mechanical dot gain) due to mechanical fluctuations. Is small. On the other hand, the decrease in optical sharpness (optical dot gain) determined by the type of recording medium is caused by the diffusion of light in the recording medium, and has a relatively large effect on the decrease in sharpness in the low frequency range. In other words, in the low frequency range, the optical dot gain due to the diffusion of light in the recording medium is dominant over the mechanical dot gain due to the printer drive.

The diffusion of light in the recording medium is mainly determined by the thickness of the receiving layer, the particle size of the receiving material, and the refractive index of the surface of the recording medium. Therefore, the type of recording medium and the presence or absence of CL ink have a great influence on the deterioration of sharpness in the important area. Furthermore, since the thickness of the receiving layer and the particle size of the receiving material have a greater effect on the decrease in sharpness than the refractive index on the surface of the recording medium, the linked LUT related to the type of recording medium is more important than the presence or absence of CL ink. Priority is given to layering.

FIG. 10 shows an example of the linked LUT of Example 2. FIG. 10A shows the linked LUT of the first layer related to the type of recording medium, and the number or filter number of the linked LUT of the second layer is different from the symbols A, B, C, ... Assigned. For the symbol indicating the type of the recording medium, for example, the product model number of the recording medium can be used. Further, in the following, the linked LUT of the first layer will be referred to as a “parent linked LUT”, and the linked LUT of the second layer or lower will be referred to as a “descendant linked LUT”.

In the case of recording medium C to which a filter number is assigned, the recovery filter is determined only by the parent-linked LUT. In other words, the recording medium C cannot change the recording medium having less influence on the decrease in sharpness of the important area due to the setting of the items of other output conditions, or the items of other output conditions (other output conditions). Means a recording medium (where the item is fixed).

Note that "the effect on the decrease in sharpness of the important area is small" means that substantially the same judgment in step S505 does not change. Further, the fixed item of other output conditions refers to a case where only a specific mode can be set in order to avoid ink overflow on plain paper, for example. Also, even if CL ink is recorded on art paper, the CL ink penetrates and the gloss effect cannot be obtained. Therefore, "Use CL ink" cannot be set for art paper.

On the other hand, in the case of recording media A and B to which the number of the progeny linkage LUT is assigned, the frequency characteristic of the important region can be changed by setting the items other than the recording medium, so the recovery filter cannot be determined only by the parent linkage LUT. .. FIG. 10B shows an example of the progeny-linked LUT, and the progeny-linked LUT number or the filter number is assigned according to the presence or absence of CL ink. In other words, if the recovery filter is determined by the presence or absence of CL ink, the filter number of the recovery filter is assigned, and if the frequency characteristics in the low frequency range can change due to the setting of other output condition items, the progeny linkage LUT Number is assigned.

In this way, for example, until the filter number is assigned for the first time from the recording medium, the linked LUTs are hierarchically created for each output condition item, and the linked LUTs are stored in the parameter holding unit 105.

In step S203, the filter selection unit 106 accesses the parent linkage LUT of the processing parameter holding unit 104 and acquires the recovery filter if the filter number is assigned to the number of the recording medium indicated by the output condition. .. If the progeny-linked LUT number is assigned to the recording medium number indicated by the output condition, the progeny-linked LUT is accessed to obtain the filter number or the progeny-linked LUT number.

Considering the layering of the linked LUT, it is preferable that the setting is made from the item of the output condition which has a great influence on the decrease in sharpness of the important area. FIG. 11 shows an example of a UI suitable for a linked LUT having a hierarchical structure. Figure 11 shows an example of the UI displayed at the top of the UI for items with output conditions that have a greater effect on the sharpness reduction of important areas. By making it impossible for the user to set items below the unset items so that each item is set in order from the top, user settings are made in the order of items that have a large effect on the reduction in sharpness of important areas. .. In addition, it is sufficient to realize the setting in the order of items having a large influence on the decrease in sharpness of the important area, and the UI for setting only one item in the order may be sequentially provided.

In this way, the linked LUT is layered based on the degree of influence of the output condition item on the decrease in sharpness of the important area. Then, by eliminating the need for the record of the linked LUT for the item of the output condition after the recovery filter is confirmed, the memory amount required for the parameter holding unit 105 can be suppressed or the memory consumption of the parameter holding unit 105 can be reduced. Can be done.

Hereinafter, the image processing and information processing of Example 3 according to the present invention will be described. In the third embodiment, the same reference numerals may be given to the configurations substantially the same as those in the first and second embodiments, and detailed description thereof may be omitted.

In Examples 1 and 2, the output condition was used as the information for selecting the recovery filter, in other words, the information for determining the deterioration characteristic of sharpness (hereinafter, the determination information for the reduction characteristic). Then, using the linked LUT that associates the output condition with the recovery filter, recovery processing using a common recovery filter is performed for the output condition that can be regarded as having substantially the same reduction characteristics of sharpness in the important region.

However, the decrease in sharpness of the output image is affected not only by the output conditions but also by the change in light when observing the output image. For example, when the angle or direction of the light source with respect to the output image changes, the shape, orientation, and size of the range affected by the optical dot gain change. When the observation conditions (position of the observation light source, the viewpoint position of the observer, etc.) are determined, such as when the output image is attached to the wall surface, it is preferable to perform the recovery process according to the observation conditions.

In the third embodiment, in addition to the output condition, the process of creating the linked LUT with the direction and angle of the observation light source with respect to the output image (hereinafter referred to as the light source condition) as the determination information of the reduction characteristic will be described. Then, when the reduction characteristics of the sharpness of the important region are regarded as substantially the same for the output conditions and the reduction characteristics of the sharpness of the important region are regarded as substantially the same for the light source conditions, the shared recovery filter is associated. Do.

FIG. 12 shows an example of the change in sharpness reduction when the angle and direction of the light source with respect to the image are changed. The light incident on the output image is diffused in the recording medium of the image, and the sharpness of the image is affected by the position of the light source. At that time, when the incident angle or direction of the light changes, the diffusion direction of the light changes, so that the decrease in sharpness becomes anisotropy. FIG. 12 (A) shows the decrease in sharpness when the light source is in front of the image. FIG. 12B shows a decrease in sharpness when the incident direction of light is tilted upward by 45 degrees with respect to the normal of the image plane. FIG. 12C shows a decrease in sharpness when the incident direction of light is tilted 45 degrees to the right with respect to the normal of the image plane. As described above, since anisotropy occurs in the decrease in sharpness depending on the light source conditions, it is necessary to give anisotropy to the recovery filter.

[Overview of image processing]
The outline of the processing in the image processing apparatus 100 of the third embodiment will be described with reference to the flowchart of FIG. The recovery processing unit 108 inputs the image data i to be image-formed from the information processing device 150 or the like via the data i / o 104, and stores the input image data i in a memory unit 101 such as RAM (S1201). ).

The condition acquisition unit 103 acquires the output condition Oi of the image forming unit 108 (S1202) via the UI unit 102 or from the information processing device 150, acquires the direction Ld of the light source (S1203), and acquires the angle of the light source. Get La (S1204). Figure 14 shows an example of the UI for specifying the direction Ld of the light source. In addition, FIG. 15 shows an example of the UI for specifying the angle La of the light source. Although FIGS. 14 and 15 show a UI for designating the approximate direction and angle on the screen, a UI for numerically inputting the direction and angle may be used.

Next, the filter selection unit 106 accesses the linked LUT held by the parameter holding unit 105 to acquire the recovery filter Ri corresponding to the output condition Oi, the light source direction Ld, and the light source angle La (S1205). The recovery processing unit 107 executes sharpness recovery processing by the recovery filter Ri on the input image data i, and stores the image data i'after the recovery processing in the memory unit 101 (S1206). Then, the image forming unit 108 forms the image represented by the image data i'after the recovery process on the recording medium 208 based on the output condition Oi (S1207).

[Linked LUT including light source conditions]
FIG. 16 shows an example of the linked LUT in Example 3. The linked LUT of the third embodiment stores the filter number of the recovery filter corresponding to the light source condition (direction of the light source and the angle of the light source) in addition to each item of the output condition shown in FIG. Similar to the first embodiment, in addition to the output conditions, the frequency response value in the important region is measured for each direction of the light source and the angle of the light source, and the maximum value (or average value) of the difference between the response values is smaller than the predetermined value. In that case, it is determined that the frequency characteristics are substantially the same, and the same recovery filter is associated with the same recovery filter. The frequency response value in Example 3 is measured by taking an evaluation chart of sharpness for each combination of the direction of the light source and the angle of the light source shown in FIGS. 14 and 15.

However, as shown in FIGS. 12 (B) and 12 (C), in a general recording medium, the diffusion direction of light changes depending on the direction of the light source, but the diffusion shape hardly changes if the angle of the light source is constant. Therefore, from the viewpoint of the amount of memory, it is preferable that the recovery filter stored in the parameter holding unit 105 is common for each angle of the light source. In that case, the difference depending on the direction of the light source may be absorbed by rotating the array of filter coefficients by a predetermined angle, for example, when acquiring the recovery filter or during the recovery process.

In FIG. 16, filter information 1 (45 °) shows the use of a recovery filter in which the array of filter coefficients of the recovery filter of filter information 1 (0 °) is rotated 45 degrees clockwise. Of course, if the reduction characteristics of sharpness are substantially the same even if the light source conditions are different, the recovery process may be performed without rotating the array of filter coefficients.

It should be noted that the determination as to whether or not the frequency characteristics substantially match is performed based on the frequency response value of the important region acquired by using the sharpness measurement chart as shown in FIG. Even if the output conditions and the light source conditions are different, the frequency characteristics are considered to be substantially the same when the maximum value (or average value) of the difference between the response values in the important region is equal to or less than a predetermined value regardless of the direction of the stripes. Therefore, the sharpness measurement chart used in Example 3 includes spatial frequency patterns with different stripe directions. It is preferable that the spatial frequency patterns having different stripe directions include patterns having the same spatial frequency and orthogonal stripe directions.

If the light source condition is not specified, the recovery process may be performed using the light source condition in a general-purpose observation environment. In that case, substantially the same judgment is made based on the light source conditions in a general-purpose observation environment. In a general-purpose observation environment, for example, the light source is arranged in a hemispherical shape in front of the image or in a ring shape at 45 degrees to the normal of the image surface so that anisotropy does not appear. Alternatively, place a point light source above the image and at 45 degrees to the normal of the image plane.

In this way, by preparing the recovery filter in consideration of the light source condition when observing the output image, it is possible to recover the sharpness decrease due to the light source condition at the time of observation.

Hereinafter, the image processing and information processing of Example 4 according to the present invention will be described. In the fourth embodiment, the same reference numerals may be given to the configurations substantially the same as those in the first to third embodiments, and detailed description thereof may be omitted.

In Example 1-3, a method of using a common recovery filter for the output condition and the light source condition, which can be regarded as having substantially the same sharpness reduction characteristics in the important region, will be described using the linked LUT. did. However, according to such a method, it is not possible to perform appropriate recovery processing on an output condition that does not exist in the linked LUT, for example, a recording medium that is not registered in the linked LUT.

In addition, the amount of memory of the parameter holding unit 105 can be suppressed by holding in advance a plurality of recovery filters corresponding to the output conditions for which a recovery filter is to be created strictly, such as frequently used and the highest grade. Can be considered. In that case, for output conditions for which strict creation is not essential, it is necessary to select an appropriate recovery filter from the recovery filters held by the parameter holding unit 105.

To solve the above problems, a specific frequency pattern is output under the output conditions for which the recovery filter is selected, and the frequency response value of the output pattern is acquired. Then, based on the acquired frequency response value, a recovery filter that does not cause excessive recovery processing and has a high recovery processing effect may be selected. Hereinafter, the process of Example 4 for selecting the recovery filter will be described.

[Device configuration]
The frequency response acquisition unit 211 shown in FIG. 1 causes the image forming unit 108 to form a measurement chart of a specific frequency pattern under the output conditions for which the recovery filter is selected. Then, using the same measuring device as in the first embodiment, the information necessary for calculating the frequency response value (for example, the luminance value, the density value, the reflectance, or the information that can be converted into them) is acquired from the measurement chart. Then, select the recovery filter that applies to the target output conditions.

The frequency response acquisition unit 211 may be realized by supplying the information processing apparatus 150 with a program for executing the processing (S1703-S1709) of the frequency response acquisition unit 211, which will be described later, and the CPU 151 executing the program. ..

[Image processing]
The processing in the image processing apparatus 100 of the fourth embodiment will be described with reference to the flowchart of FIG. The recovery processing unit 107 inputs the image data i to be image-formed from the information processing device 150 or the like via the data input / output unit (i / o) 104, and the input image data i is used as a memory unit 101 such as RAM. Store in (S1701).

The condition acquisition unit 103 acquires the output condition Ox of the image forming unit 108 via the UI unit 102 or from the information processing device 150 (S1702). The frequency response acquisition unit 211 determines whether or not a record corresponding to the output condition Ox exists in the linked LUT held by the parameter holding unit 105 (S1703). When the record corresponding to the output condition Ox exists in the linked LUT, the subsequent processing is the same as the processing in steps S203-S205 in FIG. 2, and detailed description thereof will be omitted. The processing when the record corresponding to the output condition Ox does not exist in the linked LUT will be described below.

The frequency response acquisition unit 211 supplies the image data of the measurement chart including the period pattern of the specific frequency fx [cycle / mm] read from the parameter holding unit 105 to the image forming unit 108, and measures it on the recording medium under the output condition Ox. Form a chart (S1704).

FIG. 18 shows an example of a measurement chart of a specific frequency pattern. The measurement chart shown in FIG. 18 includes a plurality of sine wave patterns and uniform patterns as in the measurement chart of FIG. 6, but the spatial frequencies of the sine wave patterns are all specific frequencies fx.

Next, the frequency response acquisition unit 211 acquires the information necessary for acquiring the frequency characteristics from the measurement chart (S1705). The frequency response acquisition unit 211 may acquire the information input from the information processing apparatus 150, or may acquire the information from the scanner when the image processing apparatus 100 includes a scanner.

Next, the frequency response acquisition unit 211 calculates the frequency response value for the periodic pattern of the frequency fx under the output condition Ox based on the information acquired from the measurement chart (S1706). As the frequency response value, the MTF (fx) described in the first embodiment or the CTF value using a rectangular wave as the periodic pattern can be used.

Next, the frequency response acquisition unit 211 acquires the recovery characteristic Ri (fx) at the frequency fx of each recovery filter Ri held by the parameter holding unit 105 (S1707). For example, the parameter holding unit 105 may hold a list of recovery characteristics Ri (fx) at the frequency fx of each recovery filter Ri, and the frequency response acquisition unit 211 may read the recovery characteristics Ri (fx) in association with the filter number. ..

Next, the frequency response acquisition unit 211 calculates the frequency response value MTF _Ri (fx) after the recovery process when the recovery process is performed using each recovery filter Ri by the following equation (S1708).
MTF _Ri (fx) = MTF (fx) × Ri (fx)… (4)

If the frequency characteristic G (fx) at a specific frequency fx is not corrected in the measuring device that measures the measurement chart, the frequency response value MTF _Ri (fx) is calculated using the following equation that cancels the frequency characteristic G (fx). calculate. The frequency characteristic G (fx) may be stored in the parameter holding unit 105 in advance or obtained from the information processing device 150, for example.
MTF _Ri (fx) = MTF (fx) × Ri (fx) / G (fx)… (5)

Then, the frequency response obtaining unit 211, the calculation result of the MTF _Ri (fx) is 1 or less, and selects the restoration filter Ri corresponding to the MTF _Ri (fx) closest to 1 as a recovery filter Rx. Then, a record indicating the correspondence between the output condition Ox and the recovery filter Rx is registered in the linked LUT (S1709). The subsequent processing is the same as the processing in steps S203-S205 of FIG. 2, and detailed description thereof will be omitted.

Further, the correspondence between the output condition Ox and the recovery filter Rx may be stored in another table other than the linked LUT. In that case, the determination in step S1703 and the acquisition of the recovery filter in step S203 by the filter selection unit 106 refer to the table in addition to the linked LUT.

As described above, when the frequency characteristic after the recovery process exceeds 1, the enhancement process is performed instead of the recovery process, and the excessive recovery process causes adverse effects such as noise enhancement, brightness reduction, and ringing. Therefore, the recovery filter Ri whose calculation result of MTF _Ri (fx) does not exceed 1 (does not result in excessive recovery processing) and is closest to 1 (highly effective in recovery processing) is selected as the recovery filter Rx. ..

Figure 19 describes the selection of the recovery filter and the frequency response value MTF _Ri (fx) after the recovery process. In FIG. 19, the horizontal axis shows the spatial frequency [cycle / mm], the vertical axis shows the recovery characteristics, and the broken line shows the specific frequency line fx. FIG. 19A shows an example of the characteristics of the recovery filter Ri held by the parameter holding unit 105, and the intersections of the broken line and the recovery characteristics of each recovery filter Ri are listed and held by the parameter holding unit 105. The recovery characteristic Ri (fx) of the recovery filter Ri.

Figure 19 (B) shows an example of frequency response values MTF _Ri after recovery processing (fx), the response value is 1 or less, and, closest MTF _Ri to 1 (fx) is the MTF _R4 (fx). In this example, the recovery filter R4 corresponding to MTF _R4 (fx) is selected as the recovery filter Rx.

Note that the reciprocal 1 / Ri (fx) of the recovery characteristics and the frequency response value MTF (fx) may be compared in step S1708 without calculating the frequency response value MTF _Ri (fx) after the recovery process in step S1707. .. In that case, a list of the reciprocals 1 / Ri (fx) of the recovery characteristics at the specific frequency fx of each recovery filter Ri is stored in the parameter holding unit 105. Then, the recovery filter Ri corresponding to 1 / Ri (fx) which is equal to or higher than MTF (fx) and is closest to MTF (fx) is selected as the recovery filter Rx.

FIG. 19 shows an example in which seven recovery filters R1-R7 exist. However, in the fourth embodiment, the recovery filter held by the parameter holding unit 105 may be two or more, and the recovery filter corresponding to the output condition for which the recovery filter is to be strictly created, such as frequently used and the highest grade, is used as a parameter. It may be held by the holding portion 105. Alternatively, the parameter holding unit 105 may hold a recovery filter that minimizes the total error when applied to various expected output conditions.

Further, in order to surely avoid excessive recovery processing, a recovery filter having a recovery characteristic of 1 regardless of frequency (a center filter coefficient of 1 and other filter coefficients is 1) like the recovery filter R7 shown in FIG. 19 (A). 0) is preferably stored in the parameter holding unit 105. Of course, if there is no recovery filter with a recovery characteristic of 1 and MTF _Ri (fx)> 1 for all recovery filters Ri, do not perform recovery processing (S204) to avoid excessive recovery processing. May be good.

As described above, in order to select the recovery filter Rx in the region that is visually sensitive and has less noise and brightness reduction in the printer output, the specific frequency fx is set to the spatial frequency in the important region (below the visual limit frequency). .. In addition, an example of selecting the recovery filter Rx based on the frequency response value MTF (fx) of a specific frequency fx was shown, but the frequency response values MTF (fm) -MTF (fn) of multiple frequencies fm-fn in the important region were used. The recovery filter Rx may be selected based on this.

Scanners, digital cameras, microscopes, microdensitometers, etc. are used to input the information required to acquire the frequency characteristics, but instead, the user may input information related to the sharpness of the important area. .. For example, the frequency response value MTF (fx) at a specific frequency fx may be input, or the information of a recording medium having a large influence on the frequency characteristics in the low frequency region may be input. As the information of the recording medium, the category of the recording medium (glossy paper, art paper, etc.), the thickness of the recording medium, the presence or absence of the receiving layer, the basis weight, the whiteness, and the like can be considered.

Hereinafter, the image processing and information processing of Example 5 according to the present invention will be described. In the fifth embodiment, the same reference numerals may be given to the configurations substantially the same as those in the first to fourth embodiments, and detailed description thereof may be omitted.

In the fourth embodiment, a measurement chart of a specific frequency pattern is formed in order to select a recovery filter, and a recovery filter to be applied to the target output condition is selected from the frequency response values calculated based on the information in the measurement chart. An example was explained. However, information in real space (mechanical dot gain or optical dot gain) can also be used as information for selecting a recovery filter. That is, the influence range of the dot gain can be used for the determination information of the lowering characteristic. Then, the influence range of the dot gain is measured, and a recovery filter corresponding to the output condition in which the difference in the influence range is equal to or less than a predetermined value is selected.

[Device configuration]
The influence range acquisition unit 212 shown in FIG. 1 causes the image formation unit 108 to form a dot pattern under the output conditions for which the recovery filter is selected. Then, using the same measuring device as in Example 1, the information necessary for acquiring the influence range of the dot gain (for example, the luminance value, the density value, the reflectance, or the information that can be converted into them) is obtained from the dot pattern. Select the recovery filter that is acquired and applied to the target output conditions.

The influence range acquisition unit 212 may be realized by supplying the information processing device 150 with a program for executing the processing (S1803-S1811) of the influence range acquisition unit 212 described later and executing the program by the CPU 151. ..

[Image processing]
The processing in the image processing apparatus 100 of the fifth embodiment will be described with reference to the flowchart of FIG. The recovery processing unit 107 inputs the image data i to be image-formed from the information processing device 150 or the like via the data input / output unit (i / o) 104, and the input image data i is used as a memory unit 101 such as RAM. Store in (S1801).

The condition acquisition unit 103 acquires the output condition Ox of the image forming unit 108 via the UI unit 102 or from the information processing device 150 (S1802). The influence range acquisition unit 212 determines whether or not a record corresponding to the output condition Ox exists in the linked LUT held by the parameter holding unit 105 (S1803). When the record corresponding to the output condition Ox exists in the linked LUT, the subsequent processing is the same as the processing in steps S203-S205 in FIG. 2, and detailed description thereof will be omitted. The processing when the record corresponding to the output condition Ox does not exist in the linked LUT will be described below.

The influence range acquisition unit 212 supplies the image data of the measurement chart including the rectangular pattern read from the parameter holding unit 105 to the image formation unit 108, and forms the measurement chart on the recording medium under the output condition Ox (S1804). FIG. 21 shows an example of the measurement chart of the rectangular pattern and the influence range of the dot gain. The measurement chart shown in FIG. 21 (A) has a size of, for example, 84 × 84 μm (2 × 2 dots at 600 dpi, 4 × 4 dots at 1200 dpi).

Next, the influence range acquisition unit 212 acquires the influence range rw (x) and rh (x) of the dot gain from the measurement chart (S1805). The influence range acquisition unit 212 may acquire the influence range input from the information processing device 150, and when the image processing device 100 includes a scanner, the influence range acquisition unit 212 acquires the influence range based on the information input from the scanner. You may.

The affected areas rw (x) and rh (x) are blurred areas excluding the rectangular pattern region (84 × 84 μm) of the measurement chart, as shown in FIG. 21 (C). In other words, the range of influence is the distance from the edge (or center) of the rectangular pattern area (84 x 84 μm) to the point where it can be considered that there is no change in density in the horizontal direction (or the point where it can be regarded as having the same density as paper white). rw (x). The points that can be regarded as having no change in density are the points that are sufficiently separated from the rectangular pattern and the points that have the same density in consideration of the measurement error. Similarly, the range of influence rh (x) extends from the edge (or center) of the rectangular pattern area to the point where it can be considered that there is no vertical density change (or the point where it can be regarded as having the same density as paper white). The distance.

Next, the influence range acquisition unit 212 acquires the influence ranges rw (i) and rh (i) of the dot gain under each output condition Oi held by the parameter holding unit 105 (S1806). The range of influence of the dot gain in each output condition Oi is measured in advance without applying the recovery filter Ri corresponding to the output condition Oi.

Next, the influence range acquisition unit 212 calculates the difference Δr (x, i) between the influence range under the output condition Ox and the influence range under each output condition Oi by the following equation (S1807).
Δr (x, i) = √ [{rw (x) --rw (i)} ² + {rh (x) --rh (i)} ² ]… (6)

Next, the influence range acquisition unit 212 searches for the output condition Oi in which the difference in the influence range is less than a predetermined value and is the minimum (S1808). That is, the output condition Oi which is regarded as substantially the same as the sharpness lowering characteristic of the output condition Ox and has the most similar sharpness lowering characteristic is searched for. The predetermined value used for the search is preferably, for example, a conversion value of 0.25 mm (250 μm) for a length of 4 cycles / mm, which is the upper limit of the important region, but is not limited to this value.

Next, the influence range acquisition unit 212 determines whether or not the output condition Oi having the sharpness lowering characteristic which can be regarded as substantially the same as the sharpness lowering characteristic of the output condition Ox is detected (S1809). When the output condition Oi is detected, the influence range acquisition unit 212 selects the recovery filter Ri corresponding to the output condition Oi as the recovery filter Rx. Then, a record indicating the correspondence between the output condition Ox and the recovery filter Rx is registered in the linked LUT (S1810).

Further, when the output condition Oi having the sharpness lowering characteristic which can be regarded as substantially the same as the sharpness lowering characteristic of the output condition Ox is not detected, it is necessary to avoid excessive recovery processing. Therefore, for example, the influence range acquisition unit 212 displays this fact on the UI unit 102, and selects the recovery filter R7 having the recovery characteristic 1 shown in FIG. 19A as the recovery filter Rx. Then, a record indicating the correspondence between the output condition Ox and the recovery filter Rx is registered in the linked LUT (S1811). The subsequent processing is the same as the processing in steps S203-S205 of FIG. 2, and detailed description thereof will be omitted.

As in the fourth embodiment, the correspondence between the output condition Ox and the recovery filter Rx may be stored in another table other than the linked LUT. In that case, the determination in step S1803 and the acquisition of the recovery filter in step S203 by the filter selection unit 106 refer to the table in addition to the linked LUT.

In the above, for the sake of simplicity of the explanation, the determination of substantially matching when the output conditions are different has been described as an example, but it is also possible to determine the substantially matching when the light source conditions are different. However, if the light source conditions are different, anisotropy of bleeding occurs. FIG. 22 shows the anisotropy of bleeding when the light source conditions are different. In consideration of this anisotropy, rw1 (x), rw2 (x), rh1 (x), and rh2 (x) are measured as the range of influence of the dot gain as shown in FIG. Then, the output condition Oi in which all the influence ranges are smaller than the predetermined value (for example, 0.25 mm) and the difference Δr (x, i) shown in the following equation is less than the predetermined value is searched.
Δr (x, i) = √ [{rw1 (x) --rw1 (i)} ² + {rw2 (x) --rw2 (i)} ²
+ {rh1 (x) --rh1 (i)} ² + {rh2 (x) --rh2 (i)} ² ]… (7)

Further, the influence range of the dot gain can be acquired by using a thin line chart or an edge pattern chart. Further, the dot gain caused by the recording medium, which has a particularly large influence on the decrease in sharpness, can be measured by the spread of the impulse light, the slit light, and the edge light. In other words, the use of the rectangular pattern measurement chart is an example of a method of measuring the dot gain influence range, and the measurement of the dot gain influence range is not limited to the use of the rectangular pattern measurement chart.

[Other Examples]
The present invention supplies a program that realizes one or more functions of the above-described embodiment to a system or device via a network or storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by processing. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

103… Condition acquisition unit, 106… Filter selection unit, 107… Recovery processing unit

Claims (6)

A condition acquiring means for acquiring the output conditions of the image forming unit,
In the output condition acquired by the condition acquisition means, it is determined that there is no corresponding record in the lookup table that holds each of the plurality of output conditions in association with the recovery filter for recovering the sharpness of the image. The frequency response value for the periodic pattern of a specific frequency in the image formed on the recording medium by the image forming unit is acquired based on the information acquired from the measurement chart including the periodic pattern of the specific frequency formed on the recording medium. Frequency response value acquisition means and
It corresponds to the look-up table that holds each of a plurality of output conditions in association with a recovery filter for recovering the sharpness of an image based on the output condition and the frequency response value acquired by the condition acquisition means. the Kide force condition before the condition obtaining means records is determined that there is no acquired, the information processing apparatus characterized by having a registration means for registering in association with the recovery filter. The registration means recovers the sharpness of the image output by the image forming unit based on the output conditions acquired by the condition acquisition means by the recovery filter held in the look-up table, and the condition acquisition means The information processing apparatus according to claim 1, wherein the acquired output condition is associated with the recovery filter that most recovers the sharpness of the image. Claim wherein the recovery filter that best restore sharpness of the image, the result of applying the recovery filter in the frequency response value is 1 or less, and, which is a closest consisting recovery filter 1 The information processing apparatus according to 2. Claims 1 to 1, wherein the recovery filter is a parameter of a recovery filter for recovering the sharpness of an image output by the image forming unit based on the output conditions acquired by the condition acquisition means. The information processing apparatus according to any one of 3. Get the output conditions of the image forming unit,
The image forming unit determines that there is no corresponding record in the lookup table that holds each of the plurality of output conditions in association with the recovery filter for recovering the sharpness of the image. The frequency response value for the periodic pattern of the specific frequency in the image formed on the recording medium is acquired based on the information acquired from the measurement chart including the periodic pattern of the specific frequency formed on the recording medium .
Based on the acquired pre Kide force condition and said frequency response value, the look-up table holding in association with each of a plurality of output conditions on the restoration filter to recover the sharpness of the image, it records the corresponding presence the information processing method characterized by non with the determined acquired before Kide force conditions, is registered in association with the recovery filter. A program for causing a computer to function as each means of the information processing apparatus according to any one of claims 1 to 4 .